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Alum Main Cap preference for RB build #3065858
08/06/22 06:38 PM
08/06/22 06:38 PM
Joined: Jan 2003
Posts: 520
Shannonville, Ont
Blown 68 R/T Offline OP
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Guys who are running alum main caps, what's your "go to" brand? I need a decent cap for my 512 build.
I used BCR caps & girdle in the past on boosted build and never had an issue. Recently ordered a new set of "BCR style" caps to switch girdle over for new build but they don't hold their shape after installing so they are useless (should be made out of 7075 alum NOT 6061! So looking for other options. I'm leaning towards Indy's or Mancini's. Does anyone have a pic of what the Indy alum caps look like?.

Re: Alum Main Cap preference for RB build [Re: Blown 68 R/T] #3065939
08/06/22 11:11 PM
08/06/22 11:11 PM
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jwb123 Offline
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I run aftermarket blocks now, but the last set Of aluminum caps I ran were from mancini. When you say they will not hold their shape, they must be line bored and honed, after installation. Are you saying they distort after proper machine work?

Re: Alum Main Cap preference for RB build [Re: jwb123] #3065947
08/07/22 12:00 AM
08/07/22 12:00 AM
Joined: Jan 2003
Posts: 520
Shannonville, Ont
Blown 68 R/T Offline OP
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JWB i sent ya a pm

Re: Alum Main Cap preference for RB build [Re: Blown 68 R/T] #3065960
08/07/22 12:57 AM
08/07/22 12:57 AM
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Cab_Burge Offline
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I don't like and won't use a stock 440 block for a hot street build over 700 HP due to the main webbing being weak, to thin. tsk twocents
I suggest finding a decent 400 block that mags and sonic tests good and use it with a 440 Source aluminum main caps and ARP main studs, have them fitted to your block and go have some fun without worrying about running over the crankshaft after several runs,
My last 400 S/P stroker build was 505 C.I. with 15.0 to 1 compression for racing with E 85, it had a set of Indy 440-1 CNC ported with an Indy 400-3 intake and Holley 1150 CFM Dominator converted to E 85 by A.J. at Bob George racing.
I had that motor in a chrome moly tube chassis 1970 Cuda with 4 link rear suspension with an A arm front suspension with coil overs, double adjustable shocks on all four corners, it weighed 2850 Lbs. with me in it ready to race. It had a Powerglide in it along with a Dana 60 with 40 spline Mark Willaims axles and spool, 4.56 gears up shruggy
Best1/4-mile ET was 8.862 at 150..+(CRS blush) MPH in July at Woodburn's Mopar race two years ago, best 1/8 mile was 5.50 at 125.6 MPH at Madras last August: boogie:
it would 60 ft in the low 1.21 up to 1.30 depending on the track and weather boogie
it would set me way back in the seat off the trans brake boogie devil

Last edited by Cab_Burge; 08/07/22 01:01 AM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Alum Main Cap preference for RB build [Re: Cab_Burge] #3066035
08/07/22 12:33 PM
08/07/22 12:33 PM
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Connecticut
FurryStump Offline
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I know nothing of big blocks, but a very good machinist I met who worked on F1 stuff in the past and other exotic stuff made the comment when we were running a 400 with aluminum caps. He said “it is VERY difficult to not have the cast iron block bias the tooling into the aluminum” again not a big block guy and don’t know the problem that aluminum caps are trying to solve, but it stuck with me.


best of 11.53 at 117 mph 1.62 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]
Re: Alum Main Cap preference for RB build [Re: FurryStump] #3066039
08/07/22 01:06 PM
08/07/22 01:06 PM
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Warren, MI
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Jerry Offline
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the aluminum caps solve a couple of problems. 1 they add strength to the caps as the aluminum is stronger than the cast iron factory caps. 2. the caps help decrease cap walk, for further stregnth add the girdle to hold the caps down even more. our caps are made taller so the girdle has direct contact with them. the main problem on the big block is the main webbing breaks when theres alot of power.


Superior Design Concepts
2574 Elliott Dr
Troy MI 48083
jerry@sdconcepts.com
www.sdconcepts.com
Facebook page: Superior Design Concepts
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Re: Alum Main Cap preference for RB build [Re: Jerry] #3066041
08/07/22 01:24 PM
08/07/22 01:24 PM
Joined: Jan 2003
Posts: 520
Shannonville, Ont
Blown 68 R/T Offline OP
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Jerry
Sent ya a pm and also to your work.

Re: Alum Main Cap preference for RB build [Re: Blown 68 R/T] #3066048
08/07/22 02:11 PM
08/07/22 02:11 PM
Joined: Jan 2003
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Shannonville, Ont
Blown 68 R/T Offline OP
mopar
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Huge shoutout to Jerry at SD Concepts for the quick response and proactive customer service in regards to sorting out the issue with my caps.

Re: Alum Main Cap preference for RB build [Re: Jerry] #3066180
08/08/22 10:20 AM
08/08/22 10:20 AM
Joined: Oct 2004
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Connecticut
FurryStump Offline
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Originally Posted by Jerry
the aluminum caps solve a couple of problems. 1 they add strength to the caps as the aluminum is stronger than the cast iron factory caps. 2. the caps help decrease cap walk, for further stregnth add the girdle to hold the caps down even more. our caps are made taller so the girdle has direct contact with them. the main problem on the big block is the main webbing breaks when theres alot of power.

So the aluminum helps absorb some shock and keeps it out of the webbing? A billet cap could accomplish the “stronger, less cap walk” goal? I don’t even know if billet steel caps exist.


best of 11.53 at 117 mph 1.62 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]
Re: Alum Main Cap preference for RB build [Re: FurryStump] #3066187
08/08/22 10:46 AM
08/08/22 10:46 AM
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U.S.S.A.
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Originally Posted by FurryStump
Originally Posted by Jerry
the aluminum caps solve a couple of problems. 1 they add strength to the caps as the aluminum is stronger than the cast iron factory caps. 2. the caps help decrease cap walk, for further stregnth add the girdle to hold the caps down even more. our caps are made taller so the girdle has direct contact with them. the main problem on the big block is the main webbing breaks when theres alot of power.

So the aluminum helps absorb some shock and keeps it out of the webbing? A billet cap could accomplish the “stronger, less cap walk” goal? I don’t even know if billet steel caps exist.


Yes they somewhat absorb the shock but they can still walk if you throw enough power at them. Adding the girdle helps with the walk as helps limit the flexing, they are basically a bandaid. I thought that the crossbolted cap was the answer, and liked that Indy crossbolted all 5 caps was a great idea till I saw the carnage that Steve Morris showed recently on his youtube channel of his SMX engine having all 8 rods shatter at almost 8000 rpm and the crank still able to rotate, his block design has splayed cap bolts into the main webbing. I can't say if a crossbolted block would have had the same results?

Mopar at one time had a ductile iron cap available as a replacement for the cast iron caps. I scooped up a couple sets before they went NS1 , one set I used , the other set are hiding somewhere .


running up my post count some more .
Re: Alum Main Cap preference for RB build [Re: JohnRR] #3066234
08/08/22 01:56 PM
08/08/22 01:56 PM
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Jerry Offline
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we can make billet steel caps but unless your actually cracking the aluminum caps they wouldn't help, all the shock would be in the main webbing. technically with all of these "solutions" none of them are bullet proof. cross bolted caps actually weaken a block not designed for them, because you have to remove a reinforcing casting rib to add the cross bolt. we actually made a girdle to fit a JP1 hemi as the customer was already experiencing cap walk with cross bolted caps. after redesigning the caps to look like ours, we kept the cross bolts and added the girdle and he hasn't had any problems since.


Superior Design Concepts
2574 Elliott Dr
Troy MI 48083
jerry@sdconcepts.com
www.sdconcepts.com
Facebook page: Superior Design Concepts
www.bcrproducts.com
Re: Alum Main Cap preference for RB build [Re: FurryStump] #3066245
08/08/22 02:20 PM
08/08/22 02:20 PM
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Cab_Burge Offline
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I used to use the Mopar brand ductile iron main caps on my engine builds that would make over 700 HP, they wouldn't stop the stock 440 blocks from cracking in the main webs between the bottoms of the cylinders into the mains whiney
When Mopar quit selling them I looked into what replacement main caps were available and ended up choosing the 440 Source aluminum main caps with their ARP main studs and I have not had a failure in 15 yrs. luck
Milidon sells steel caps, but I don't use them due to the expansion rate differences between cast iron and steel: work:
The 400 blocks don't crack in the main webbings, and they have a bigger bore to start with than any other Mopar B or RB blocks also up scope
Your best bet on making a safe drag race engine using a Mopar wedge type block is a new one in aluminum or cast grey iron: uptwocents: scope: Buy a KB, World, Bill Mitchel or whoever else you can get a new block from luck

Last edited by Cab_Burge; 08/08/22 02:23 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Alum Main Cap preference for RB build [Re: Cab_Burge] #3066309
08/08/22 06:20 PM
08/08/22 06:20 PM
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Hot Rod Ridge
FastmOp Offline
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My alum block has steel caps lmfao

Re: Alum Main Cap preference for RB build [Re: FastmOp] #3066509
08/09/22 11:42 AM
08/09/22 11:42 AM
Joined: Oct 2004
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Connecticut
FurryStump Offline
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Thanks, learn something new everyday.


best of 11.53 at 117 mph 1.62 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]
Re: Alum Main Cap preference for RB build [Re: FastmOp] #3066536
08/09/22 01:11 PM
08/09/22 01:11 PM
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Originally Posted by FastmOp
My alum block has steel caps lmfao
All of the aluminum BB and street Hemi Mopar's blocks I've worked on had steel caps also: work:

Last edited by Cab_Burge; 08/09/22 01:12 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)






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