4 Bolt Splayed Main Caps - Whos who

[92whitedak]

I'm looking at both Milodon and Pro Gram as far as two manufacturers of 4 bolt splayed main caps. There prices seem pretty much equal (225 from Milodon, 237 from Pro Gram). Who converted from a 2 bolt main block to a 4 bolt main block. I know I want to go splayed, did anyone go that route? Lets get some feedback as far as which of the two is better, worse, and why. Thanks felluhs.

[turbododge]

What block are you using? On my 340 block the splay bolts broke into the crankcase and the water jacket, which I am told is normal. It can be a bit of a pain to keep the water completely out of the oil. Mine were Miloden. On an "X" block or any full web block, it would not be a problem.

[92whitedak]

I'll be using a 77 360 block.

[skankweirdall]

Why are you wanting to put 4 bolt mains on it? I've always used two bolt mains with studs and have never had a problem I'd think unless it's a full web block adding the extra bolt holes would weaken the block.

[92whitedak]

From what I've been reading in a couple of small block mopar books and hearing from the guys I'm talking to, the difference between splayed main caps and regular 4 bolt caps with bolts that go directly straight is that the splayed mains grab from the side of the block, instead of the main web. This is going to be a very high-hp, high-tq, high-no2 engine and aside from the forged 4.00 crank, I'm trying to do anything I can to keep my bottom end intact.

[skankweirdall]

If I were you I'd consider very strongly one of the R3 blocks with siamese bores and 4 bolt mains, or at the least the 340 replacement block. It has 4 bolt mains as well. I really don't see a later model 360 block taking that kind of abuse for very long. It would be cheaper in the long run to get the good block to start with IMHO.

[turbododge]

I would have to agree that a better block would probably be worth the investment. You are going to have a lot in it, so I don't think I would take a chance. The 340 replacement should hold up well with the 4 bolts, filled rails and webs, and filled front face. I don't know for sure, but are the R3 blocks all for dry sumps and other all race stuff?

[92whitedak]

Count me out if the r3 block is for dry sump only. I'm going to be using w-2 heads. Is there a race block that accepts w-2 heads. I'd really like to not have to go to p-5 or above heads simply for the cost. Also, do any of the race blocks allow for solid mechanical cams? I don't know much about the race blocks, except for that thats probably what I'm going to have to use. Damn.

[BugEyedValiant]

Not all R3 blocks are for dry sump. There are MANY R3s and there are only 3 R3 blocks that are dry sump blocks in the 2002 MP catalog. You will be able to get whatever combo(as in bore size, deck height and lifter angle) you want.

[92whitedak]

Heres what I'm looking for, if anything. An H style main web, like the X block capable of bolting w-2 heads to. I DON'T want this to be a roller engine. I'd like to use basically everything for a regular 360 engine but have the extra benefit of the larger web structure. Is there a block like this?

[skankweirdall]

You can. These are all 4 bolt main 9.56 deck height blocks. The only real mods I had to do to the last one I got was plug the top two timing cover bolts and redrill and tap new ones (they are in a different place for extreme decking, plug the dry sump port with a pipe plug and flatten, and add oil drain back holes to the lifter valley. They come solid.

P4876673AB siamese bore 48*, 318/340 main
P4876793AB siamese bore 59*, 318/340 main
P4876674AB non siamese bore 48* 318/340 main
P4876794AB non siamese bore 59* 318/340 main
P4876796AB non siamese bore 59* 360 main

If you are buying the heads new I strongly suggest the 48* heads and blocks. It of course requires a different camshaft.

There is also the 340 replacement block max bore 4.08 4 bolt caps (none of these are splayed by the way) P5007552.

That P4876793AB block is on sale until the end of this month for right at $1300.00 dealer cost, so depending on the dealer as to how much of those savings he'd pass on to you.

[sanborn]

Just a couple suggestions:
1. I would use the 59 degree lifter bore block with the 18 degree W2 heads. Get the block with the 360 main journal size.
2. If you choose to go otherwise, talk to someone that knows exactly which block will work with which head. Unfortunately, I don't know of anyone to talk to.

Let me explain about #1.

If you are going to use a 4" steel crank in a high torque application, I would prefer the larger main size of the 360 to get the maximum journal overlap.

The W2 heads come in 18 and 15 degree versions. The 15 degree versions are for a 48 degree block, require a lot of work to get them to flow well on the intake and require a set of T&D rockers. The T&D rockers will only work on 48 degree blocks and offset roller lifters(unless you do a lot of grinding for pushrod clearance). The 18 degree heads will fit on the 48 degree block but machine work is required(unless done at the factory).

The 48 degree block uses relocated lifter bores and the change in lifter bore angle requires a non standard camshaft core. Mopar shows them in the catalog but VERIFY they are actually available before you go off down this road. The cores were not available earlier this year. They had plenty of stock of roller cores-just no flat tappet cores.

I would also use the standard deck height block, shorter decks require clearance work for the push rods.

If you use an "R" block, keep in mind the water flow through the block. The small water inlet at the front of the block will not flow enough water for most applications. The front opening can be enlarged or you can plumb water into the side of the block(which is the way the low deck blocks were designed for anyway).

If you use a siameze block, make sure you drill the additional water flow holes between the cylinders to eliminate air pockets.

Be careful buying used blocks. Many use needle bearing cam bearings. You are limited to roller cams only. Also, many Nascar blocks use GM size lifter bores. Some had 2.25" main journals.

Unless you just want to spend extra $, I would stay with the 59 degree "R" block and 18 degree W2 heads.

[92whitedak]

Thanks for all the great advice guys. Concidering my options and what I want to get out of this engine, I'm going to have to go with a race block. P4876796AB (the 59* lifter bore block) with 18 degree w-2 heads sounds like the route I'm going to go. 1k hp small block, here I come Is there any way or any reason to fill in the outter two main cap bolts and re-drill and tap splayed caps? Or are these blocks designed to work with the 4 bolts that go straight into the main web? And what about bore sizes? I've read the rough bore comes out to 4.09. How big can you take that out to?

[skankweirdall]

There is no reason to change the main caps on that block, it's not a Chevy and will handle 1000+ HP. As for the bore size on that particuliar block, they are rough bored to 3.98, max bore size is 4.08.

[skankweirdall]

But, there are still 4 W5 heads left, they take the same hardware as W2's, except the intake, they are 40lbs. lighter per set and they flow better with less work. Dealer cost at $550 each.

[92whitedak]

The reason I want to run the w-2 heads is clearly because of the flow ability. The best I can get a w-5 head for around me is 632. w-2 I can get for just under that at 462. I understand that the w-5 has a much larger intake and you can get a w-5 head to outflow a w-2 but one of the key components to this engine is going to be the tunnel ram. Do they (MP or otherwise) offer a tunnel ram for w-5 heads? For the additional 300-400 bucks from w-5 heads to w-2 heads, is it going to be worth it? Mind you, I'm not crazy, just shooting for 1000hp. Are w-5s my best bet?

[92whitedak]

I just did some research and found out that there is a Large Rectagle port 2x4 Aluminium tunnel ram for the w-5 heads. ($241.50, P4529875) Humm..... Now you've got the gears turning skank. For some reason, I always limited myself to w-2 heads because I was afraid of venturing further, afraid that I'd have to go to a weird and $$ rocker setup, custom exhaust flange and intake. Last question before I'm sold on the idea. Have any flow numbers off-hand for a w-5 head, or a rough guess at what they are capable of (cfm/lift) and will they accept a standard exhaust manifold?

[skankweirdall]

A standard header gasket will bolt up, the port holes don't line up to well though. I used the W2 headers on mine with the adapter plates. Only way to go in my opinion.

Next, I got W2's first, thought like you did, but then decided to go ahead and take the leap, man am I ever glad I did. With just mild work around the guides and some minor pocket and bowl work these things flow 300 cfm's at .600 lift with a 2.02 valve. 306 at .650 lift, I believe the 2.02 valve is holding it back at this point. But never the less that is enough flow to make 600 naturally aspirated horsepower. It was money well spent in my opinion. I mean how many 3000lb. Dusters that still have all the factory glass and steel are there running around out there with just a 360 and a flat tappet cam?

http://www.fenderforum.com/userphoto...html?recid=632


It does have a 'glass hood and bumpers though because good straight steel ones are hard to find.

[92whitedak]

Interestingly enough, this engine is going in a 70-73 Duster. I refuse to put it in anything else I'm in love with the cars, just haven't found one that I'm ready to take the leap on yet. But this w-5 idea is really starting to make my wallet itch. I was aware that the w-2 had two bolt patterns, one for regular headers, the other for w-2 style headers. You said you needed an adapter plate for the exhaust manifolds? Is this a w-2 to w-5 adapter? Any idea on how much larger you can cut the seats to slip in some bigger valves? I need to start getting some flow numbers together.

[skankweirdall]

The adapter just takes the regular exhaust bolt pattern and allows you to bolt a bigger header flange to it. It's the same for the W2 and W5. In other words you have to run a W2 header, the stockers would probably bolt up but the port shape and placement is so different it wouldn't seal.

I'm thinking about putting the 2.08 valve in mine this winter. It is I believe as large as you can go without moving the guides or using a smaller exhaust valve.

[turbododge]

As long as the R3 experts are here Are the R3 blocks suitable for street use, with standard iron heads? In particular, do the have adequate cooling provisions, mounting for accessories, etc. It would be nice to be able to build a very high boost motor, and not be so limited on bore size as the 340 replacement block is.

[skankweirdall]

There are conflicting opinions on whether or not a siamese bore block would be OK in a street application. I haven't tried it myself nor do I know of anyone personally that has. Although I wouldn't have a problem trying it. I've heard of drilling holes between the bores, but how that would effect ultimate bore size and how to exactly place those holes is something I'm unaware of.

[sanborn]

Sure, you can use siameze bore blocks on the street(all GM 400 blocks are siameze bore blocks). You just need to pay attention to the water flow in order to get good UNIFORM cooling. Since the water flow is blocked between the cylinder walls, the block can create air pockets and you can get the top side water at a different temperature than lower side water. And, a piece of cast iron doesn't like to be heated to two different temperatures.

The drilling of small holes between the cylinder bores is no big deal. All it does is eliminate air pockets and allow a small amount of water to flow up into the head(holes need to be drilled in the head as well) in an attempt to equalize cooling. Go to the oval track chat section, look up "cooling modifications" and there are photos of the hole drilling as well as other cooling stuff. Also look at the photo of an "R" block with a side water manifold. While you are at it, look up the "typical oiling modifications".

As to bore size- I used several "X" blocks over the years, never had a problem with 4.100" bores. The non siamize "R" blocks should go as large. The siamize bore "R" blocks should be safe to at least 4.200". For example, when the "R" block, W8 headed engines were used in Nascar Supertruck competition, the "Standard" bore was 4.185" with a 3.25" stroke for the limit of 357". From there, the Nascar teams would freshen the bore by going up .002" in bore size each time until they got to about 4.190" then the block would be discarded. They did pay VERY CLOSE attention to water circulation and the blocks had several additional water flow holes to get uniform temp around the cylinder bores. Also, keep in mind the engines produced 750+HP, constantly were at 8000-9400RPM, and for up to 500 miles. And the blocks were the same ones you buy from MOPAR. But, they were no "stock out of the crate". They received a bunch of thoughtful work before use.

As to "Four Bolt" main caps. The splayed caps are nice, look sexy, and are probably really needed on GM blocks. The standard Mopar four bolt caps (with vertical bolts) are very beefy, the "R" blocks are very beefy and should work without problems. If you have never seen the bottom end of a Mopar race block then you are in for an experience. Even the main caps of a two bolt "X" block are much beefier than a stock main cap. And, the four bolt caps are 50% beefier than a GM four bolt cap.

As to cylinder heads. W2s are really good heads. They can be worked to flow really good #-but it takes serious work. W5s can flow as much (really slightly more) than W2s. And, the work to get good # is less and is easier because it's aluminum. The practical maximum valve size on either W2 or W5s is 2.080"/ 1.625". You can get more but you run out of valve bowl. A really good set of W2 or W5 heads will flow 325CFM/215CFM @.700". But, if both sets flow that amount, the W2s will produce more power due to the cast iron. The W5s were originally cast for Nascar Supertruck competition. They didn't flow or perform as well as the 18 degree GM heads, so were replaced by the W7 head, later the W8 head. That's not to say they arn't good, they are, but just not as good as the GM head. Both W2 and W5 heads take the same valves, rockers, stands, shafts, valve covers, and the same intake. The W2 intake can be ported to a rectangular shape for the W5s.

Now, if you want to get the latest technology type of cylinder head, think about a W8 or W9 head. The ports are raised about .750" on intake and .500" on exhaust, use 15 degree valve angle(12 degree if desired), have better combustion chambers and will outflow and GM 18 degree or Ford 10 degree head. Valve sizes can go up to 2.200"/1.650". Flow gets up to around 380 CFM @.700" (properly prepared). Ain't bad for a SB head. There are down sides also, primarily $$$, for rockers, intake, valve covers, etc. But, if you want max HP, that's the way to go.

While I'm on this subject, let me talk about W2, W5, W8, W9 and P7 heads. All good aftermarket heads. The W2 and W5 flow about the same(properly worked), the W8 and W9 flow about the same(properly worked) and the P7 is the best. But the P7 is only better above 8200RPM. Below that it is no better, actually is not quite as good at low RPM(4000 and below). You can make the P7 head work as good at low RPM but then it doesn't work better at high RPM. Sounds strange doesn't it. But said another way, it is a "special purpose" head only designed for very high RPM. But, the P7 headed(R5 block) produces about 815HP every weekend on the race track-not bad for 357" on gas with an 830CFM carb.

Well, I guess I have beat this subject to death. I guess this old geezer needs to get some ZZZZZZZZZZZZZZZZZZZZZzs.