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Frequently Asked Questions/Tech Topics

(See Photos Below)

Can I put W7, W8, or W9 heads on my factory 340/360 block or 59 degree R3 block?
What does a "Siamese bore" block mean, and how do I know if my block is Siamese or not?
How far can I safely bore my block?
How do I identify a specific MP race block?
What are the differences between W7, W8, and W9 heads, and which one is "best"?
Mopar Performance Race Block, Frequent Machining Problems Identified
Using Cometic Head Gaskets


Can I put W7, W8, or W9 heads on my factory 340/360 block or 59 degree R3 block?

 This is probably becoming my most frequently asked question lately, since the marketplace seems to be flooded with W7/8/9 cylinder heads with MP discontinuing some of the W9s and a lot of used CNC ported heads popping up around the country.
The simple answer is YES. But as we all know, nothing when dealing with Small Block Mopars can be simple. This is going to be a complicated long, drawn out answer, but hopefully you will be able to follow along and I won't have to re-type this on a daily basis.
Let's begin with factory 340/360 blocks as the R3 is a slightly different animal in a few key areas. Any W7/8/9 head will bolt directly to a 10 bolt factory block. They all utilize the standard factory 10 bolt location. However some people get confused because they hear that many W7/8/9s have 18 head bolt holes. MOST do (but not all, some early W7s are 10 bolt only) Those extra 8 head bolt holes do NOT have to be utilized, you can just run the standard 10. However you will need to utilize a specific W7/8/9 longer head stud kit. Your basic factory, or W2/5 head stud kit won't work. As far as head gaskets go, just run your standard 10 bolt, Fel Pro #1008 composite or Cometic 10 bolt LA style Multi Layer Steel head gasket.

  So bolting the heads to the block was not overly difficult. The next major obstacle becomes pushrod clearance. The W7/8/9 style heads generally have a much wider intake port runner tract than more normal 59 degree style heads. Generally, with a standard non offset lifter and a standard W7/8/9 rocker arm, you will have pushrod to intake runner wall interference. Certain rocker arms make this interference worse than others. Most Jesel brand rockers for instance will have less offset on the intake rocker than T&D rockers. Obviously the less offset, the more interference with the runner wall. As a general rule of thumb, standard off the shelf T&D rocker arms for W7/8/9 heads will have .550" offset on the intake rocker. All the ones sold through Mopar Performance have .550" offset. Now, T&D will custom make you any offset between .550" and .725", so if ordering new, you can get more offset. Jesel will also build custom rockers with increased offset, however most customers to save money want to use existing rockers that are floating around for sale, and most of these are not wild offset rockers. On everything I have tested to date, a .550" offset intake rocker WILL clear the inner runner wall on any CNC W7/8/9 head with a non offset lifter, but it is VERY close. The outer runner wall has to be notched VERY carefully by hand for clearance, and a 5/16" pushrod is all that will fit. A 3/8" pushrod will break through into the inner runner wall on most heads, and will require an epoxy fix.

  To make the situation better, you can use an offset intake lifter. The problem here is that most lifter companies do not cater well to the Mopar crowd when it comes to offset lifters. In fact to the best of my knowledge, no Hydraulic or Flat tappet lifters exist in .904" Chrysler diameter. A couple companies offer an offset Solid Roller lifter, and generally speaking, when you are thinking of running a W7/8/9 head, you are probably already thinking of running a roller anyhow. One of the problems I ran into was the fact that the Comp Cams #892 "Super Roller" lifters don't fit 59 degree blocks? No way, no how. The rivet design on them will not clear the lifter valley area, even with intense grinding. You will most likely hit the water jacket if you try to make these rivets clear. The lifter I am currently recommending that everyone use is a Crane .903" Chevy Solid Roller lifter with a .210" intake offset pushrod cup, and then have Crane install Chrysler "V" Link bars on them. In a factory block, these will allow a 3/8" pushrod to be used. If you want to use a Hydraulic or Flat tappet cam, then I am recommending just use the standard non offset AMC style lifters, and a 5/16" Heavy wall pushrod like a Smith Brothers .080" wall Chrome Moly unit.

  Now to make matters worse, W7/8/9 heads do not oil the rockers through the heads, like you are used to on LA style heads. W7/8/9s use pushrod oiling with individual mount rocker arms that are mounted to a large one piece rocker stand in pairs of rockers. The only other option to oil these types of rocker arms is to have spray bars TIG welded in your valve covers and spray bar oil the rockers. This works well with Jesel type rocker arms that spray the rocker arms as it is for oiling, but T&D rockers, which are a fully pressurized rocker body, need modifications to be spray bar oiled. My personal recommendation is to use spray bar oiling as a last resort. Pushrod oiling is the preferred method to oil W7/8/9 rocker arms.

  Pushrod oiling rocker arms on a stock factory 59 degree LA engine block can get tricky. If you are using AMC style Hydraulic or Flat tappet lifters, it will work OK. Basically all you are doing is putting on a head/rocker combo that pushrod oils like a Magnum head conversion. The problem comes when you start running large lift solid roller camshafts. You can drop a solid roller lifter right in your factory LA block, and it will get some oil to the top end, but the engine generally will have excessively low oil pressure, and bearing damage will be imminent. There are two ways around this. One is to have your lifter bores bushed, with bronze bushings and run a small .035" oil feed hole in the bushings. The bushings job is basically to act as an oil restrictor, to restrict the amount of oil that is being bled off around the lifter. Also another thing you run into on factory blocks more so than on R3 race blocks, is that the lifter bores have 100,000+ miles on them in most cases, and the bores are usually not located properly in regards to angularity. So bushing the lifter bores corrects both of these problems. The downside? Cost. Having your factory lifter bores bushed is generally a $450-$600 machining operation, depending on the shop doing the work, and not every shop owns the proper BHJ fixture for bushing Small Block Chrysler lifter bores. However there is a second and less expensive way out of this predicament. You can install copper tubes in both the lifter oil galleys. Both passenger side AND drivers side. Then you can drill your .035" oil feed holes in the copper tube in each lifter bore, and the tube is what acts as your oil restrictor. Mopar Performance has sold the lifter bore tube and peen package for more than 20 years to block off all oil to the lifter bores. We are just putting a new twist on this old idea. With the tubes installed, your oil pressure will be back up to normal levels and your bearings will thank you for it.
As far as R, R1, R1A, R2, and R3 race blocks are concerned, the only differences that you need to be aware of, is the fact that the inner row of extra head bolts, and their bosses will need to be HEAVILY milled/ground off for link bar clearance on a solid roller lifter application. This is a time consuming and tedious task, that has to be done VERY carefully or you will break into the water jacket. Also, even the R3 block will still require you to either bush the lifter bores or tube the galleys to restrict the oil to the roller lifters, there is no way around this. The oil feed holes in the lifter bores are just too large out of the crate.
  And there you have it, those are the basics of installing a W7/8/9 cylinder head on a 59 degree engine block. Now for the part most people don't think about/know about. MOST W7/8/9 heads have 15 degree valve angles. Stock LA heads utilize an 18 degree valve angle. This creates obvious problems when trying to just bolt a W7/8/9 on a standard 18 degree shortblock/piston combo. There is no easy way around this other than just having Custom 15 degree relief pistons made. Besides the fact, that W7/8/9s have wider valve spacing than most LA heads, and they usually utilize larger diameter valves as well. All of these factors necessitate that custom pistons be used under a W/7/8/9 head. The good news is, that with today's CNC technology, Custom pistons are not nearly as expensive as they were only 10 years ago. Today, most piston companies will do a fully custom piston combo for around $150-$200 extra. Well worth the cost, when you consider the added power gain of using a large "W" series cylinder head. For more info, and differences of W7/8/9 heads see the W7/8/9 section of the FAQs.

What does a "Siamese bore" block mean, and how do I know if my block is Siamese or not?

  First, let me state that the ONLY Small Block Chrysler engine blocks ever cast that were Siamese bore, are R2/R3/R4/R5 iron blocks.
Factory 273/318/340/360, T/A, X blocks, R blocks, R1, and R1As, were never available in Siamese bore. So if you have anything other than an R2/R3/4/5 you don't have Siamese bores.

  Simply put, the Siamese bore blocks have the cylinder walls "Siamesed" or "adjoined" together in between the cylinders. There is no air gap for water to pass through between the cylinder bores. This added material built up between the bores allow the cylinder walls to be enlarged to much larger bore diameters before the wall thickness becomes too thin to safely operate. (NOTE: See Photo #3) For instance a non Siamese block at 4.125" bore may only have .120" of iron left on the non-thrust sides of the cylinder walls. This would be getting close to the maximum bore you can safely run on a block that will be making significant power. Now in a Siamese bore block, at 4.125" bore we may have .300+" of iron before we hit the opposite cylinder, which obviously leaves room to run a much larger bore.

  Simple way to check if your R3 is Siamese bore or not? Look up the part # in the Mopar Performance catalog. But not everyone knows their part # sometimes (We'll get to that in a different FAQ) So, easy way to tell is just pop out a freeze plug on the sides of the block, and just look and see if the two cylinder walls that you see have air space between them, or if they are Siamesed together, and have a mass of cast iron between the walls.

How far can I safely bore my block?

  I'm often stumped why people ask this question, because unless I have ESP or some other psychic ability, I can not answer this question definitively. SONIC testing is the only definitive way to know what your specific blocks cylinder walls look like thickness wise. HOWEVER, I will give you some generalities, just because so many people want to know. Do not take the following as gospel - only the sonic tester knows for sure.

  318 blocks don't like large bores PERIOD. .030" over is about the maximum I will go before sonic testing a 318 block.
  340 blocks: any year, 1967-1973, 4.04" is stock bore, and .030" over is generally very safe. .040" over I would have no qualms generally doing. Going .060" over to a 4.10" bore on a factory 340 block IMO is pushing it, and I would only do this knowing my sonic #s. Largest known running 340 block that I know of is at 4.125" bore.
  360 blocks: and here we get into certain years being felt to be better than others. Generally yes, any 360 block up until 1974ish is considered a little better block. And the above rules for a 340 apply. 1975 and later, I will go .040" over with no qualms. I have also seen many blocks from the late 70s go 4.07" or more and be used as successful race blocks for many years. However, I'd sonic test the newer stuff if going much over .040".
  X block, R block, R1, R1As: These are all non Siamese bore. MP recommends a max overbore of 4.08" on these blocks, however most people find that this is erring on the side of caution. Many of these blocks can go 4.10", 4.125" or even larger bore on occasion. My personal feeling is anything over 4.10" on these and we sonic test. Up to 4.10" I would not generally do it. Largest running non Siamese bore X, R, R1, R1A, or R2 I know of would be 4.155"
  Non Siamese R2/R3s, the above rules apply. Largest running non Siamese bore R3 I know of, is at 4.165"
Siamese Bore R2/R3 race blocks: 4.180" is a common bore size to run on these blocks, and many will run 4.22" as well. I personally would run up to 4.22" without sonic testing. Over 4.22" and I would sonic test. Largest bore running R3 engine that I personally know of, is at 4.25" bore.

How do I identify a specific MP race block?

 This is probably #2 FAQ I get asked on almost a daily basis. I'm going to start out with X blocks and work our way up through the generations.
X block is simple to identify, they have a large "X" cast into the passengers side front of the block to the left of the timing cover, behind where the alternator would sit on a factory engine setup. It is plain as day and you can not miss it. If you've got a block with a Large "X" here, it's an "X" block. Pretty simple. (NOTE: See Photo #1) MOST X blocks were 318/340 main, but a little known factoid is that a SMALL # of 360 main X blocks were produced. The lifter valley in an X block, closely resembles a factory production block. The majority of its strength was gained in the increased deck thickness and the main webbing/pan rail areas. The bores are generally also a bit thicker in all directions VS: a factory block. All "X" blocks are 59 degree lifter bank angle.
  R block: Again, where you would see an "X" on an "X" block, these have a Large "R" cast in. (NOTE: See Photo #7) The "R" block was the successor to the "X" block. It was available in 59* and 48* lifter bank angles. The main benefit to the "R" block was the addition of availability of 48 degree heads, and the lifter valley area was greatly strengthened. All "R" blocks have 10 head bolt pattern. Some EARLY "R" blocks did not have the "R" designation, but yet had the traditional "R" series large lifter bosses, and 48 degree bank angle. These were generally pre-production blocks.

  R1 block: These have a large "R1" logo on the passenger side front of the block. The biggest change in the R1 series was the addition of 18 head bolt bosses for use with the 48 degree large "W" series 7/8/9 heads. Both 59 degree and 48 degree versions available.
R1A block: Large "R1A" logo, again on the passenger side front of the block. (NOTE See Photo #4)These are 18 bolt blocks, with a cut out inner lifter valley that looks much like a factory block. (NOTE: See Photo #2) Both 59 degree and 48 degree versions available.
R2 block: Large "R2" logo on passenger side front of the block. "R2" still maintained a traditional wet sump lifter valley cutout. Available in 59* and 48* versions. "R2" are probably the rarest of all race blocks, they were only available for a short time.

  R3 block: Large "R3" logo on the front passenger side of the block. Biggest change in "R3" blocks was the availability of Siamese bores, and the valley on an "R3" has been completely filled in with iron, to make running a dry sump application much easier on the engine builder. R3s were available in the widest range of configurations, including 360 mains, both 59* and 48* versions, and deck heights varying from 9.025" to 9.56" R3s are the most common of the "R" Series blocks that you will run into at swap meets etc.
Now that we have the basic generations covered, I'll go through to how to ID exactly what version of a particular generation you may have run into.

  First off let's get the whole 48 Degree VS: 59 Degree thing out of the way. This is very easy to Identify, even for a novice. 59 degree lifter bores are always down close to the edge of the lifter valley. (NOTE: See Photo #6) That is a 59* R3 block. The 48* lifter bores are raised much higher on the lifter bosses and are much closer toward the cam tunnel. (NOTE See Photo # 2) That is a 48* R1A block. Also if you pay attention in Photo #2, I noted how the intake lifter bores are also moved side to side to accommodate better pushrod angles on the offset intake rockers. So it should be no problem to ID a 48* or 59* race block next time you see one for sale.

  The next good way to try to ID a specific MP race block is the MP PART #. Now firstly let me say, that the #s cast into the sides of a MP race block mean NOTHING. They are CASTING #s. I know they all begin with the letter "P" which would lead you to believe it is a MP Part #, but that is incorrect. The majority of race blocks share the same casting #, so it does absolutely no good to know it. What you should be looking for is the 3 digit PART # stamping on the block if it has one. Look on the drivers side of the block, on the front, opposite to where you find the X, R, R1, R2 R3 etc logo. If there is a 3 digit # STAMPED into the block in large #s that is your last 3 digits of the MP PART #. For example if you have an R3 block and it has a 796 stamped in that area, that block is a P4876796 59* R3, with 360 mains, 4 bolt mains, and 9.56" deck height. Now, under the block logo on the passengers side, ie. Under the R or R1 or R3 logo, you may find a 3 digit # over there. What that is, is basically the blocks machining production #. Kind of like a VIN # for blocks. If you have 001 you have the first block of that version ever machined. 078 and you have #78 etc.

  It's pretty obvious to identify 360 or 340 or Ford main journal sizes, so I won't go into that. Same goes with 4 bolt main caps, if you don't know what a 4 bolt main cap looks like you should take up pottery or knitting.

  Now the last big ID challenge is deck height. This is a tough one to explain in words what to look for. But here are a couple things to keep in mind. If the block you are looking at has a blank oil filter boss (no provisions machined for an oil filter NOTE: See Photo #8) the block is 9.025" deck and meant for dry sump use. If it has a complete factory oil filter boss area, it is either 9.20" or 9.56" deck. So the oil filter boss area is a dead giveaway for a 9" deck engine. As far as identifying a 9.20" or 9.56" deck block, that is tougher. Examining the area of material between the deck and the front water passages is the best way to know easily. Most of the early blocks were not available in 9.20" decks, so this generally only applies to R3s.

  And then we have the 340 "Resto" block. All a MP 340 "resto" block is, is a 59 degree tall deck, 340 main, 4 bolt R3 block that has had the extra 8 head bolt bosses per side milled off. (NOTE: See Photo #5) 340 restos come through machined at 9.59999" deck. (Factory blueprint spec is 9.600") Many "tall deck" race blocks will actually be machined to less than 9.60" which can make off the shelf piston/Rod combos troublesome. That is why they are called 9.56" deck blocks, they are meant to be run at 9.560" square deck or less.

?What are the differences between W7, W8, and W9 heads, and which one is "best"?

  Here is always a fun question to answer. To begin with I guess I should first state, that you can not generalize any of these 3 series of cylinder heads. The W7 had somewhere between 13-18 different versions cast in an aprox. 3 year period, and the # of CNC programs that were done on these heads is outrageous. There are 2 different generations of W8s, with multiple series in each generation, and then there is the W9 which certainly also is available in a wide variety of configurations. Let me break down the basics for you.

  W7s. W7s came out in late 1994/very early 1995. The very first generation stuff is extremely rare and was a true 18 degree cylinder head. It utilized W2/5 rocker arms, and was essentially just a modified W5, with a raised intake runner and a square exhaust port. Around Feb 1995 the first 15 degree valve angle heads came out. These also have a similar appearance to a W5 cylinder head outwardly, and the intake runner again, can be called by some an "enlarged and elongated" W5 port. They have a very unique combustion chamber shape, and intake short turn shape. These early W7s still retained W2/5 valve spacing with larger OD seats that allowed a 2.125" intake valve to be run. They are drilled for standard W2/5 rocker arm oiling system, but as I said, are 15 degree valve angles, making them a non direct bolt on head for most 59 degree engines. These heads were intended for very early NASCAR craftsman truck prototype development, as Chrysler was just starting to get its feet wet back in NASCAR racing. Some very early Craftsman Trucks actually ran W5 cylinder heads, and the W5 had been campaigned in ARCA competition, by folks like Bob Keselowski.

  Getting back to W7s the next generation W7s took on a life of their own and started to leave their modified W5 heritage, and became their own head. The days of using W2/5 rocker arms were over, and the "Lazy W" W7 rocker system came into fruition, as the W2/5 shaft mount rocker system had its limitations for high RPM NASCAR use. The standard 5 bolt rocker hole patterns was not able to maintain valvetrain stability, the true "Lazy W" bolt pattern uses 12 bolts to hold the rocker stand to the cylinder head. 8 3/8" bolts and 4 5/16" bolts per head are utilized. The other major change to the W7 heads at this time was the widening of the intake ports, and making them shorter and higher off the deck. The W7 evolved into a somewhat standard port window dimension of 2.15" tall, 1.40" wide and 1.35" off the deck.. Previous W7 intake port windows, were as large as 2.45" tall, 1.45" wide 1.30" off the deck. The exhaust port on the W7 still remained a large square shape for quite some time. The valve spacing was widened to allow the use of 2.15" or larger intake valves.

  The W7 at this point also went to a big block style dry intake manifold, with separate valley tray requiring AN style water return lines. The previous W7s still used a traditional SB Chrysler wet style intake manifold, with an integral thermostat housing. These intakes were only made for a short period of time and are extremely hard to locate today.

  Some of these earlier W7 heads were still 10 bolt heads, middle generation ones evolved and had the 18 bolt "ears" cast on the outside, but were never drilled/plunge cut for the 18 bolt blocks, and then finally the later stuff was all setup for 18 head bolts.
The W7 finally evolved a bit more, and the last generation stuff, uses a D shape Ex port (Early W7 is Square, late W7 is D), and have very small cast intake ports designed for CNC Porting. The majority of earlier W7s were designed more around a large casting with hand porting capabilities, but could be CNC ported depending on the program. The one other change was an evolution from "Lazy W" rocker arms to the more familiar today pattern, of the W8/9 staggered rocker pattern which uses 8 3/8? bolts.

  Generalizations about a W7 include: All of them use standard 5 bolt Small Block Chrysler valve covers. You have to be VERY cautious when looking at/purchasing a set of W7 heads to know exactly what you are looking at. Very early stuff as I stated were 18 degree valve angle heads. MOST W7s however are true 15 degree heads. Some early stuff used W2/5 rocker arms, some use Lazy W, and some later ones use W8/9, and there was even a FOURTH rocker arm system that was utilized for a short period of time. Rocker arms are a major issue for W7 heads. Be very cautious with these heads, to make sure you know what rocker arm system your particular set utilizes, and that you can actually get your hands on a set of rocker bars for your particular heads. In some extreme cases it may be necessary to send your particular heads to Jesel or T&D to have custom bars made. As far as head bolts go, obviously not all W7 heads are 18 bolt heads. In fact probably at least 60% were only 10 bolt heads, so don't ASSume because you are buying a W7, that you will have 18 bolt capability. Be cautious on the generation as far as how large of a valve you can install safely due to the spacing changes. If you buy an early set of 1995 W7s realize that no intake manifolds exist. You will have to go through the added time and expense to make a later style W7 dry intake manifold bolt up. Another thing that varied wildly was overall valve length. There is no one set valve length for all W7 heads. There were just too many versions made. Same goes for runner volume and combustion chamber shape/volume. Many versions were available, although ALL W7s were closed chamber of some sort. However, they can range wildly from 44 CC chambers all the way to 75+ CC. So be careful there.
Exhaust flange bolt pattern. Again, there were several different patterns used direct from Chrysler, also a lot of heads were sold blank and engine builders drilled/tapped their own particular pattern in a lot of W7s. BUT as a generality, there is one common W7 6 bolt pattern, it is different from W2/5 or W8/9. It is what I call W7 pattern. It is a straight across 6 bolt pattern. Having adapter flanges made to use standard W2/5 race headers is not overly difficult.

  It doesn't get a whole lot easier when it comes to W8 heads, but at least not so many different versions were made, but you still must be overly cautious not to lump all W8s together. W8s were designed purely for NASCAR Craftsman truck racing. Where as the W7 started life as a NASCAR truck head, and branched out into World Of Outlaws Sprint Car racing as well, the W8 was a pure NASCAR head, designed to replace the W7 and some of its inherent weaknesses. The W8 was used in some Silver Crown type cars, and I'm sure on some sprint cars here and there over the years, but it was never designed as a dirt track head.

  The original first generation W8s are from the May 1997 Casting run at Alcoa foundry. The main intent with the W8 head was to produce a much stronger version of the last generation W7s. W8s are extremely heavy cylinder heads with massive amounts of aluminum in all areas. They were designed as a pure 48 degree head with 18 head bolt bosses. They use W8/9 zig zag rocker pattern. The problem of valve spring to valve cover interference on the W7 heads, particularly when using large OD springs was fixed by widening the valve cover rails, which necessitated a special unique W8 valve cover, and gasket. The intake ports were slightly raised to 1.50" off the deck. The exhaust ports are also raised from W7, and use a unique flange bolt pattern. All W8s were cast with very small chambers, and ports. They are all intended to be CNC ported. This is not to say that they can NOT be hand, ported, but in reality, I have only seen ONE set of hand ported W8s in existence (done for Competition Eliminator). 99% of W8s you will run into are CNC ported by one company or another. Of the original 1997 castings, there are what are known as "circle track" and "Drag" heads. There are two big differences between them. The first is a slightly different exhaust flange bolt pattern. The pattern looks similar, but is different in overall dimension. All W8s have a 7 bolt Exhaust flange pattern. The major change between a drag W8 and a circle track W8 is the valve angle. Most Drag W8s were 13 degree valve angle, and most circle track W8s are 15 degree. NASCAR limited Chrysler to 15 degree otherwise they would have ran less valve angle, and testing was done at Arrington racing engines on sub 15 degree W8s for NASCAR use, but were never run in competition.

  In 2000 a second run of W8 castings were made, and this time the foundry was changed to the Zeus foundry rather than the old standby of Alcoa Aluminum. A few new changes were added including extra water line outlets near the deck on the front face of the heads, and these heads have a 2000 casting date cast into them with slightly different MOPAR logos. (The logo is smaller)

  I should also at this point probably discuss some of the "custom" castings that also exist, including Comp Eliminator and Lemans type heads. First off, there are VERY limited amounts of 9 degree W8s that were cast/machined for use in Pro Stock truck, and NHRA Competition eliminator. Before these heads ever really hit the P/S scene the P5 head was released to replace W8 Wedge heads in P/S truck. The 9 degree W8s would be the some of the rarest of the rare, and also probably the most powerful W8s in existence. The other "exotic" W8 heads would be some of the custom castings done for the Chrysler 24 hour of Lemans program. These include castings with TEN valve cover bolt bosses/holes, and some have special fuel injector bosses cast right into the top of the intake port runners, requiring a special custom made valve cover. While rare, these Lemans heads have recently been dumped onto the market, and special consideration needs to be made before acquiring a set of these heads. They also feature slightly taller intake faces, and the port windows are 1.70" off the deck,and the valve angle is 12 degrees.

  Now, as far as ports and chambers in W8s go. Since 99.99% of all W8s are CNC'd by one company or another it is hard to lump all W8 ports into any one category. As a generalization, most W8 intake ports will have a port window somewhere around 2.20" tall, 1.40" wide and 1.50" off the deck. Runner volumes can vary wildly depending on CNC program and what the intended purpose of the head was. Some as low as 260 CC intake runners, some in the near 300 CC range. You have to realize any head CNC ported for use in NASCAR competition was limited by an exhaust port height rule by NASCAR. Chapman, Arrington, CFE, M2 etc all have CNC programs of varying types for W8 heads. Chamber volume can also vary wildly, and here is where I will also mention the RS head. RS stands for "Raised Seat". What this basically means is that the valve seats are not set deep into the combustion chamber when the seat steps are machined in the raw casting during the machining process. By leaving the valve seats closer to the deck of the head, it does several things. One is that it decreases chamber volume significantly, another is that it adds "artificial" short turn height, and increases runner volume slightly. Also because the seats are so close to the deck and the chamber is so shallow, valve unshrouding is greatly reduced. All these factors add up to increased airflow. There are downsides however. The first obvious thing is that to maintain the same valve spring installed height, an RS head requires the use of a longer valve. Generally a W8 RS head will use a valve length somewhere around 5.75"-5.80" where as a standard seat W8 head can use a 5.55" valve length and obtain the same general installed height because the seat to spring pocket height is reduced. And the other factor in using an RS type head is piston to valve clearance becomes much more of a critical issue. For the most part an RS type head requires very deep valve reliefs to be used in the pistons just die to the simple fact the valve has to travel less distance to exit the deck surface of the head compared to a standard seat head. Extremely deep valve reliefs require the top piston ring to be moved down on the piston, and can sometimes affect piston compression height abilities.

  The reason I had to go into that discussion of RS versus Standard seat heads is because you most often find the RS option being offered on W8 cylinder heads. This is not to say that it has not or can not be done on a W7 or W9, but just that it is more rare to see it done on those two head designs. And getting back to chamber volume, the 9 degree W8s obviously have the shallowest, smallest chambers out there. Some 9 degree heads will often be in the 20-25 CC range. Most used NASCAR W8 RS heads will be in the 44-46 CC range, and non RS heads will be in the 52-62 CC range as far as chamber volume goes.
  Generally, W8s are considered to be the most sought after of all the W series heads because more R&D $ was spent on the W8 than any other head, and the power output as a direct result of the R&D done on those heads shows up on the track. Most CNC W8s will make substantial power on just about any combination. However, some are obviously better than others, with short turn design varying wildly from porting houses such as Chapman and Arrington. So do not lump all W8s together and think that one will flow or make as much power as the next. There are spectacular W8s out there and then there are mediocre W8s out there. So be careful when selecting a W8 head for your particular application.

  As far as intake manifolds go, W8s are just like W7s and 9s in the fact that they use a shared intake manifold design. It is a dry manifold design that requires the use of a valley tray, and AN fittings for water return lines. W7/8/9 Intake manifolds are readily available from MP in both short deck and tall deck versions.

  And last thought on the W8 heads, valve cover availability for these heads used to be a major factor when purchasing a set of them. MP offered both an aluminum and a magnesium cast W8 valve cover over the years and both were extremely expensive. Dealer cost in the $600 range for the covers alone. Today, much more affordable sheetmetal covers are available and used Moroso sheetmetal and MP magnesium units are becoming more available.

  W9 heads....The most common mistake I see being made when it comes to W9 heads is that there is this common misconception that because a W9 has a higher # than a W7 or W8, that the W9 MUST be superior to the rest. As I said, this is a MISCONCEPTION. A W9 head is not necessarily superior to anything.

  What is a W9? Simply put a W9 is basically a lightened W8. W9s were purely intended for sprint car racing. This is why they are so light, and have down nozzle bosses cast into them. As everyone knows sprint car racers are fanatical about weight. A W9 is the lightest SB Chrysler cylinder head ever cast at 21 lbs. The valve cover rails are extremely thin, the water jackets are extremely large internally, weight was the major factor in their design. However the intake and exhaust port locations are basically identical to a W8. This is not to say the ports are the SAME as a W8, they are not. While W8s were cast very small for CNC porting, W9s are cast large, to be either CNC'd OR easily hand ported, or run right out of the box.

  W9s share the same rocker arm system with a W8 head. W9s share the exhaust bolt pattern with circle track W8 heads, so W8 circle track headers will bolt on a W9. W9s are all cast by ZEUS. Some rare ones will have a ZAP logo (Zeus Aluminum Products) W9s utilize standard LA Chrysler valve covers, that will interchange with W2/5/7s etc. W9 heads come in one basic configuration, with a ~242 CC intake port cast in it. They come in both 11/32" and 3/"? guide versions, and there is now an ?AB? W9 head that is machined at Chapman Racing Heads, that has 11/32" CV products guides,and CNC combustion chambers. "Normal" W9s come with 62 CC chambers and non raised seats. Only custom machined W9s will be RS heads. W9 exhaust ports are cast quite large and in a traditional D shape. The big benefit of using a W9 head is the fact that they can be run without being ported, or with minimal hand porting or easily can be fully hand ported, OR they can be CNC'd for max effort. Where as the W8 really must be CNC'd ie. it's more expensive, plus W8s do not come from Chrysler with seats or guides installed.

  The W9 head is not avail direct from Chrysler in an unmachined state.

  W9 is a 48* 18 bolt head, that can be utilized on a 59* block with modifications. The other nice thing about W9s is the price. Dealer cost on new bare W9 heads is less than $900 a pair.

  There is also now what is known as the W9RP head. RP stands for Raised Port. This is what is currently being run in World Of Outlaws Sprint Car 410? racing. RP heads are a special W9 casting that comes with no seats or guides, and no combustion chamber. The spark plug holes are not machined in as well allowing for ability to move the plug around in the chamber. These heads are aprox $1800 a pair bare, and require alot of machine work and must be CNC ported. W9RP heads require custom intake manifolds, and .725" offset T&D rocker arms. The exhaust side of the head is the same as a regular W9 head. The intake ports are raised aprox .800" over a standard W9. It is an 18 bolt 48 degree head that will work on any 48* race block. They take stock LA valve cover pattern. W9RP head is best flowing wedge head available for Small Block Chrysler, but along with the flow and power production comes the biggest expense of any wedge head. Ryan J.


?Mopar Performance Race Block, Frequent Machining Problems Identified

  In this article I will discuss the most common errors and problems we encounter on a daily basis with the MP race blocks, just as a warning for the do it yourselfer out there to watch out for. These problems are usually small, and can be handled fairly easily, but are the kind of problems that drive you nuts when trying to build an engine and one pops up.

  The first MAJOR issue I want to identify is the deck height problem on tall deck race blocks. As you most likely noted these blocks are referred to as 9.56" deck blocks by MP. The factory blueprint spec on a 318/340/360 factory block is 9.60" This difference causes major headaches when trying to use an off the shelf piston/rod/crank combo that is designed around the factory 9.60" deck spec. Now I will say this, SOME R3 blocks I have seen have come in square at 9.60000" right out of the crate. But the majority of early race blocks and R3s usually have deck height variation issues. One brand new R3 we just checked recently started out at 9.595" on the drivers side front of block and tapered to 9.590" at the rear of the drivers side. The passengers side was 9.590" at front and 9.595" at rear of pass side. We square decked it to 9.850" to run it with the pistons .015" out of hole. I find that these deck height variations from side to side are common, and the fact that blocks are starting out at under 9.600" is also very common. MP will tell you these blocks are intended to be square decked at 9.560" and run at that deck height or lower. So they are well aware of the issue of them being under 9.60" As for why they made these blocks a different blueprint deck height spec than the early production blocks, I have no idea. The big problem as I noted is in trying to use an off the shelf Piston/Rod/Crank combo designed for factory blocks. In the above instance with the piston .015" out of the hole I was forced to use a .054" thick Cometic head gasket to make up the difference to obtain proper piston to head clearance. I could have also flat milled the pistons .015" before balancing.

  Next issue? Crankshaft counterweight to block interference. This seems to be random. I have seen a bunch of race blocks have this issue including R1s, R1As and R3s, and some other have more than enough clearance for the exact same crank. The problem is very prevalent with the MP forged 4" crank counterweights. The problem is the undercuts on the front and back side of the main saddles that are machined for counterweight clearance, generally are just a hair too shallow, and some modest clearancing with a die grinder is necessary to take the edge off.

  Lifter bore holes. Most of the time on a brand new block, the lifters will NOT fall through the bores, you can either run a brake hone through them to take edges off or use a ball broach. I see this on most every race block.

  Oil pan problems. Don't believe what MP claims in their literature that all race blocks use a 360 oil pan. It's not correct. I'd say it's 50/50 shot on actually getting a race block that utilizes a 360 pan rear main cap. I've seen R1s with 360 pan, and some R3s with 340 caps, which according to MP isn't supposed to be, but it is. So don't be alarmed if your race block has a 340 cap on it.

  Also if you plan on running a 59* head and oiling up through the head, just double check that your race block has been drilled form the deck through to the #2 and 4 cam journals. I have seen at least one 59* race block that missed this machining operation.

  While we are on the deck of the block again, just be aware that just because a race block is 48*, do not assume that the extra head bolt bosses will be drilled and tapped for the 3.8"-16 extra 8 head studs. In fact, MOST are not. A competent machine shop should be able to drill and tap those holes for you if they have your head as a template.

  And yet still, here is one that is a real problem area. You can not use a standard 10 bolt Cometic head gasket on an R3 race block. The R3 has an undercut in the lifter valley around the non oiling inner head bolts. A standard Cometic gasket will overhang the valley in this area and leak water. You need to use what Cometic calls their "W2 R3" 10 bolt gasket. It is modified in this area to seal.

  The front lifter oil galley holes in the R3 block do not accept a standard block 19/32" press in plug. You must use a 9/16" plug.

  The intermediate shaft. You have two issues here to deal with. First off, the intermediate shaft bushing will require reaming/honing to get the shaft in with proper clearance. So don't expect it to drop right in. I usually just pop it out and replace it with a new Pioneer products unit. Second more critical issue, is that on a lot of the R3s we are running into an issue with the gear hitting the block before it can drop in fully. We are having to again take the die grinder and clearance the block in this area.

  While you are working with your die grinder, don?t forget to add oil drainback holes in your R3 lifter valley.

  Main bore line hone usually way off, so expect to spend the extra $ and line hone the block.

  While your machinist is checking that, have him stick his dial bore gauge in the cam tunnel as well, we have ran into a couple R3s that were on the small side there and required honed.

  And here are some weird random problems I have personally seen, in no specific order:

  I've seen a 9.20" deck 59* block that was machined for 48* babbit camshaft bearings.

  I built an R3 that had one of the freeze plug holes that had a casting flaw, and would have leaked if you just put a plug in it. I had to epoxy the plug in, to take up the air pocket in the casting.

  Occasionally during shipping the rear "ears" on the back of the block will break off. And fixing this is not as easy as just welding it back on, you need to get the tranny dowel pin holes lined up EXACTLY when it gets welded back on.

  Some blocks don't come with oil filter diverter plug under the #5 main cap, so make sure you install it before building.

  And here's an interesting one, a customer has a 9.56" deck 360 main R3, that was machined for a 9" deck timing cover at the top. It was not drilled for tall deck cover. So I guess the main point of this article is, you really need to pay attention to EVERY bolt hole, every machined surface etc in a MP race block. Take nothing for granted, and do all your clearancing and extra work BEFORE the block is cleaned for assembly and the cam bearings are installed. Ryan J.

Using Cometic Head Gaskets

  I decided I better write this article after speaking to several customers recently, who did not know what Cometic gaskets were, let alone how to properly install/use them. And I have also seen a lot of questions about their use on several internet web boards.
  First off Cometic is a relatively new gasket company that specializes in MLS (Multi Layer Steel) head gaskets. These gaskets have revolutionized the industry. These gaskets are a 3 piece multi layer steel design that feature embossed rings around the cylinders and all water/oil passages. The 3 gasket layers are riveted together with rivets that remain outside the edges of the block/heads. The two outer layers are coated with a black rubberized coating. In general you will spend 2 to 3 times as much on a set of Cometics as you would on the old standby Fel Pro 1008 head gaskets but you will certainly get 2 to 3 times more life and performance out of them. Cometics are generally $140-$205 a set depending on what you are buying. The nice thing about them is they are available in a wide range of bore sizes and thicknesses. Each set is custom made to the engine builders desires. Sometimes this is a bad thing in that it can take a week or more to get a set made and shipped, but I'd rather have the wide availability in custom sizes rather than having the wrong gaskets sitting on the shelf. For the small block Mopar guys like ourselves, they are available in standard 10 bolt pattern, or the 18 bolt Race block W7/8/9 or INDY/new B1-BA head pattern. We can have them made with or without the oil passage up through the heads etc. This is nice feature, when doing an internal oil setup like an INDY head on a 18 bolt race block. The Fel Pro 18 bolt gaskets do not have an oil feed hole. But I have had Cometic add that hole for me on 18 bolt gaskets in the past. The varying thicknesses allow me to play with deck height, and piston combos more so than we would have been able to in the past as well. Recently I used a set of .120" thick Cometics to deal with a domed piston and a closed chamber INDY head. In the past this combo could never have been ran together, but the Cometic gaskets made it possible.

  Customers often ask me what they can do to help seal their head gaskets. Usually they are blowing regular 1008 Fel Pros and want to know if there is something better. Well the Cometic is it. If used properly, you should not have a fire ring sealing issue with a Cometic gasket EVER. I don't care how much compression you run. They will seal 17:1+ They are resistant to methanol, race gas, nitrous oxide etc. Blowers, turbos, big nitrous loads, whatever you can throw at them, they can take it. These gaskets have made O rings and copper head gaskets almost obsolete. I don't worry about fire ring seal on Cometic equipped engines.

  Cometics do have to be used properly however to maintain their sealing capability. Cometic recommends a specific surface finish or finer on the deck of the block and head surface to seal. This raises A LOT of questions with racers. Let me just state, that this surface finish requirement is WAY over rated. Yes it is true that we try to run as smooth a finish as possible on the Cometics, but do not get overly concerned if your particular surface finish does not meet their specs. 98% of the time they will still seal fine. So don't get caught up in the surface finish game and feel that your finish is not good enough and therefore you can't run Cometics. If your heads are FLAT, and have a decent surface finish, they will seal fine. The only real weakness they have is sealing water. Every once in a while a Cometic motor will weep a little bit of water on cold start up, especially if the surface finish wasn't the best. This being said, if the deck and heads are flat, have decent finish, and the heads are torqued properly, wait untill the engine comes up to operating temp and the weeping should go away. DO NOT use any type of sealer on the heads, block or the gaskets themselves. I recommend cleaning the deck of both the block and heads with either laquer thinner or acetone (Brakleen) right before the gaskets and heads are installed. We always recommend the use of ARP head studs, and the use of ARP Moly lubricant on the studs, nuts, and washers prior to torquing. Do not clean the gaskets with any chemical, they should remain in the sealed Cometic packing until the time to use them. And as a precautionary measure ALWAYS double check and mic both gaskets before using them to make sure they are the proper thickness. Cometic can, and has made mistakes in their thicknesses before. It is easily understandable when they have so many thicknesses to choose from. So I recommend always measuring to be sure they are right, otherwise improper piston to head clearance could lead to disaster.

  One last thing that needs discussed is re-using Cometic head gaskets. Cometic will not tell you directly that they can be re-used. However, that is just to protect their bottom line and reputation in case one were to fail during re-use. My OPINION on the subject is that as long as you are re-using them on the same block and same heads that they came off of, and that the rubberized coating looks to be fully in tact, they can be re-used safely for a maximum of 3 re-torques.

  Again, if they are used properly, Cometic head gaskets can save you a lot of headaches, and IMO are one of the best products to hit the market in the past 20 years. Ryan J.


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