Installing splayed caps

[CNC BLOCKS]

I have been asked about the installation of splayed caps many times over the years. First of all this proceedure can be done in a Bridgeport, knee mill, CNC machine ETC.

I use flat bottom caps with 10 degree angle outer bolts because with the 10 degree outter bolts you should not get into the water jackets. I have had many calls about outter bolt holes getting into the water jackets only to find out its because of the 18 or 22 degree outter bolt holes.

Alot of classes out there are restricted to run OEM blocks and most racers like the weight savings of the OEM block and 383's we are now seeing over 500 plus HP and with the added stroke its best to go to a splayed center cap, Its always best to sonic test the cylinders for thickness before spending time and money on cap work.

Caps I prefer are caps from http://www.cipcoindustries.com/ or http://pro-gram.com/ Price on cipco caps are right at 160.00 a set Programs are right at 210.00 a set.

First process is to cut the register either with an end mill or I use a 2.5 shell mill on 2 bolt blocks the register has to be only cut appox. .120 deep measure of the pan and on 4 bolt blocks the register have to be cut appox. .140 deep. I like to see a .003 press fit



Next step is using a 1/2 in end mill at a 10 degree angle is to mill a flat spot.



Next is to center drill



Next drill holes using a the letter U drill appox. .800 deep



Next would be taping with a spiral tap seems to work best.



Line boring can be done with a line boring machine or I use the PLB-100 which seems to very fast and accurate, I cut the housing bores close to size.



Once line boring is complete the caps are taken off and cut appox. .0025 to .003 off the bottom then then reinstalled and aligned honed to the last .001 caps are loosened retorqued to check for size and hone to size.



Finish product


Note: On the Cipco caps they are OEM height and you can use an ARP bolt kit and on the Porgram caps they are appox. .200 taller and would require a stud kit.

Hope this thread answers most questions about cap installation.

 

[BBShark]

First process is to cut the register either with an end mill or I use a 2.5 shell mill on 2 bolt blocks the register has to be only cut appox. .120 deep measure of the pan and on 4 bolt blocks the register have to be cut appox. .140 deep. I like to see a .003 press fit

I don't know much about this process but I'll ask this anyway. By "register" I assume you mean that the web that contains the lower half of the bore is cut .120 deeper. Doesn't that offset the centerline of the bore? Also where is the .003 press at?

 

[CNC BLOCKS]

First process is to cut the register either with an end mill or I use a 2.5 shell mill on 2 bolt blocks the register has to be only cut appox. .120 deep measure of the pan and on 4 bolt blocks the register have to be cut appox. .140 deep. I like to see a .003 press fit

I don't know much about this process but I'll ask this anyway. By "register" I assume you mean that the web that contains the lower half of the bore is cut .120 deeper. Doesn't that offset the centerline of the bore? Also where is the .003 press at?

Register is where the main caps sets in the block. The center lines maybe changed when the caps are cut and a .003 cut and aligned honed you are changing the center line in a perfect world .0015

The .003 press fit is the interfearance fit block register to cap.

 

[BBShark]

OK now I think I get it. When you cut the "register" with a shell mill, the orginial depth is .117 and you cut to .120 deep. I thought you were cutting an additional .120!

 

[CNC BLOCKS]

OK now I think I get it. When you cut the "register" with a shell mill, the orginial depth is .117 and you cut to .120 deep. I thought you were cutting an additional .120!

Gm blocks the register depths are all over the place and on 4 bolt blocks they are appox. .020 deeper which will change the parting line depth but not the center line.

 

[mrvette]

Can anyone explain to me why the Factory 4 bolt setup is not as good as the above?? I simply don't see it....never did.....:hissyfit:

 

[CNC BLOCKS]

Can anyone explain to me why the Factory 4 bolt setup is not as good as the above?? I simply don't see it....never did.....:hissyfit:

Splayed caps tie the pan rail and the main webbing together, Did you ever look at a Dart block or Bowtie blocks as those have splayed caps as well.

I have seen the webbing pulled out of blocks before and the 2482 center caps blocks are hard to find, Look at the webbing on GM K block compared to a 010/020 blocks. The K blocks on the outter bolt holes I haves see those crack over the years.

Interesting you think a GM stock grey cast cap is good as a billet splayed caps HMMMM I guess myself and other engine builders see the differance

 

[turtlevette]

I guess myself and other engine builders see the differance

It's intuitive to me. The angled bolts prevent cap walk and you're tieing into the outer walls of the block to get strength from a different area. Triangulating makes the whole thing stronger, similar to installing a cage on a frame.

On my Rodeck, the main caps are impressively heavy. You know that's some serious steel as soon as you pick it up.

 

[Twin_Turbo]

I recently saw this pic on a dutch forum...what's the deal here? Looks like they peened the block because the register was too wide



Looks like this will feel tight during assembly but will lead to cap walk. Supposed to be a pretty stour engine also... it looks fubared

 

[CNC BLOCKS]

I recently saw this pic on a dutch forum...what's the deal here? Looks like they peened the block because the register was too wide



Looks like this will feel tight during assembly but will lead to cap walk. Supposed to be a pretty stour engine also... it looks fubared

I never thought studding the out side was a good idea if a stud got locked up the cap could never be removed.

I does look like someone messed up a a little.

 

[mrvette]

Can anyone explain to me why the Factory 4 bolt setup is not as good as the above?? I simply don't see it....never did.....:hissyfit:

Splayed caps tie the pan rail and the main webbing together, Did you ever look at a Dart block or Bowtie blocks as those have splayed caps as well.

I have seen the webbing pulled out of blocks before and the 2482 center caps blocks are hard to find, Look at the webbing on GM K block compared to a 010/020 blocks. The K blocks on the outter bolt holes I haves see those crack over the years.

Interesting you think a GM stock grey cast cap is good as a billet splayed caps HMMMM I guess myself and other engine builders see the differance

Thinking of mainly factory truck 4 bolt blocks vs these remachined 2 bolt aftermarket blocks, and what differences there are....I have never seen them side to side to know...so asking....got any pix of them so to see??

and maybe a guess as to legit % differences in strength??

 

[CNC BLOCKS]

Can anyone explain to me why the Factory 4 bolt setup is not as good as the above?? I simply don't see it....never did.....:hissyfit:

Splayed caps tie the pan rail and the main webbing together, Did you ever look at a Dart block or Bowtie blocks as those have splayed caps as well.

I have seen the webbing pulled out of blocks before and the 2482 center caps blocks are hard to find, Look at the webbing on GM K block compared to a 010/020 blocks. The K blocks on the outter bolt holes I haves see those crack over the years.

Interesting you think a GM stock grey cast cap is good as a billet splayed caps HMMMM I guess myself and other engine builders see the differance

Thinking of mainly factory truck 4 bolt blocks vs these remachined 2 bolt aftermarket blocks, and what differences there are....I have never seen them side to side to know...so asking....got any pix of them so to see??

and maybe a guess as to legit % differences in strength??

Some good reading and pics in this thread.

http://www.ls1tech.com/forums/advanced-engineering-tech/652566-never-seen.html

 

[turtlevette]

because the register was too wide

I thought the whole point of splayed caps is that you don't need the slot. You have tons of pressure pulling the cap from each end so it doesn't move laterally. That's the whole point of the angled bolts.

What he did looks ugly but doesn't necessarily mean there is a problem.

 

[clutchdust]

OK, so this begs the question. For those of us (like me) that are running around 400hp, is there an advantage? I guess an even broader question would be what do you think the limits are of a factory two bolt set up? Factory four bolt? Splayed four bolt? For any of the previous, is a stud girdle a worthwhile investment?
Is this a power production issue? Or more of an RPM issue? I mean, which would benefit more from splayed caps? A 383 stroker that only sees occasional bursts up to around 6200rpm? Or maybe a lower displacement motor that may see up to or beyond 7000rpm?

 

[Twin_Turbo]

because the register was too wide

I thought the whole point of splayed caps is that you don't need the slot. You have tons of pressure pulling the cap from each end so it doesn't move laterally. That's the whole point of the angled bolts.

What he did looks ugly but doesn't necessarily mean there is a problem.

The bolts are not a tight enough fit through the holes to prevent cap walk, the only way to do that is with dowels or a register like Carl does above. The angled bolts are not to keep the cap from walking, the angle is so the bolt threads ito the thickest part of the block main webbing and not close to a water jacket

 

[turtlevette]

The bolts are not a tight enough fit through the holes to prevent cap walk, the only way to do that is with dowels or a register like Carl does above. The angled bolts are not to keep the cap from walking, the angle is so the bolt threads ito the thickest part of the block main webbing and not close to a water jacket

Ok, I was thinking the Rodeck didn't have a register but now that i think about it more it does have dowels.

 

[CNC BLOCKS]

OK, so this begs the question. For those of us (like me) that are running around 400hp, is there an advantage? I guess an even broader question would be what do you think the limits are of a factory two bolt set up? Factory four bolt? Splayed four bolt?

For any of the previous, is a stud girdle a worthwhile investment?

Is this a power production issue? Or more of an RPM issue? I mean, which would benefit more from splayed caps? A 383 stroker that only sees occasional bursts up to around 6200rpm? Or maybe a lower displacement motor that may see up to or beyond 7000rpm?

Factory 2 bolts stock stroke 375 horse is max what I would use, But I have been building performance engines for 38 years have seen what works and what does not.

In a circle track engine 370 horse 2 barrel 6200 RPM two bolt mains does not work and yes a factory 4 bolt works fine.

On a 500 horse engine 3.48 stroke stock caps will work but go to a 3.750 crank you will begin to see cap fretting.

Using a stock block at 500 horse I will at least use 4 bolt billet replacement caps if its a 010/020 block not a K-block as that would get splayed caps because of the poor webbing in those blocks.

Any thing over 525 horse I go to the splayed caps.

I have repaired a lot of blocks because the right caps were not used for the HP. I also get alot of calls and emails about cap movement, Broken caps ETC. But again I do this every day.

DEPENDABILTY is key when buiding engines I don't use cast cranks or hyper pistons and I don't run into the problems like you see posted on engine forums

For any of the previous, is a stud girdle a worthwhile investment?

A stud girdle does nothing to make caps stronger they will still frett 2 bolt cpa sin a stroker build. Problem is the more stroke you use the more the caps are being side loaded. A good example is look at the 400 2 bolt and BBC's GM stayed with the wide register to have better support to keep the caps from flexing and bemore stable.

I guess an even broader question would be what do you think the limits are of a factory two bolt set up?

Lookat a GM catalog and see what they rated there 4 bolt blocks and go from there. The old Bowtie blocks that came through with 2 bolt mains was rated at 375 horse same block with splayed caps GM rated at 800 plus HP.

GM has probably done more research on what a 2 bolt and 4 bolt is good for then anyone and I would not argue with them and from what I see there not to far off. That being said what guys get away with in another issue and 99% of the time they are basing all there info on one block LOL

Most good engine builders have a good idea what is needed for caps to make a reliable peice.

Most guys that argue with me about 2 bolt VS 4 bolt blocks don't even own a machine shop or build performance engines for a living LOL.

Another good link to look over.
http://www.chevelles.com/forums/showthread.php?t=38173

 

[clutchdust]

Great. So now I will likely need to build a new block when I put the AFR heads on as I expect to be right there or hopefully a little above.
I also noted you don't use hyper pistons. What's the problem there?

 

[CNC BLOCKS]

Great. So now I will likely need to build a new block when I put the AFR heads on as I expect to be right there or hopefully a little above.
I also noted you don't use hyper pistons. What's the problem there?

What are you using for a NEW block ???

Do a search on broken hyper pistons or hyper VS forged. A hyper is nothing but a glorified cast piston. Over the years I have got guys who broke hyper forged pistons and no problmes.

Its funny no one has ever wanted to replace a forged piston with hyper piston LOL

I guess if you are doing a budget build and can't afford a forged pistons they may or may not work.