4 Bolt Main Question?
Thread Starter
Safety Car
Joined: Aug 2000
Posts: 3,909
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From: Clymer PA
4 Bolt Main Question?
My current 454 block is only a 2 bolt block. Whenever I pull the motor out this winter I plan on having the block drilled and tapped for 4 bolt main caps. Now here's the question. Should I go with Milodon splayed 4 bolt caps or a set of regular 4 bolt main caps.
I know the Milodon splayed main caps are stronger because the main bolts are angled into the block where there is more "meat" (so to speak). But are they really needed for my application? I plan on revving the motor to 6500...maybe 7000 RPMs tops. Would regular 4 bolt GM caps do the trick?
The reason I ask is because the Milodon caps are kind of expensive at $230. I can pick up a used set of GM 4 bolt caps for $25-$50. I also plan on going with ARP main studs.
*Naturally whenever I change to the 4 bolt caps I will have the block align bored.
I know the Milodon splayed main caps are stronger because the main bolts are angled into the block where there is more "meat" (so to speak). But are they really needed for my application? I plan on revving the motor to 6500...maybe 7000 RPMs tops. Would regular 4 bolt GM caps do the trick?
The reason I ask is because the Milodon caps are kind of expensive at $230. I can pick up a used set of GM 4 bolt caps for $25-$50. I also plan on going with ARP main studs.
*Naturally whenever I change to the 4 bolt caps I will have the block align bored.
Melting Slicks
Joined: Feb 2003
Posts: 2,330
Likes: 6
From: Long Island NY
Re: 4 Bolt Main Question? (bence13_33)
I think it depends on what you are planning on doing with it...if your going to beat the snot out of it and you have a NOM motor, I would keep it out and save it and buy a crate motor...if your going to just have fun, 2 bolt main is fine...
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: 4 Bolt Main Question? (bence13_33)
Shane
I am not sure if the 2 bolt and 4 bolt holes in the block are aligned meaning if you put a 4 bolt cap on the 2 bolt block you could not screw the a bolt in because the holes don't align.
I am not sure if the 2 bolt and 4 bolt holes in the block are aligned meaning if you put a 4 bolt cap on the 2 bolt block you could not screw the a bolt in because the holes don't align.
Thread Starter
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: 4 Bolt Main Question? (mvftw)
mvftw:
The motor is far from original :) .... and yes I do plan to beat the snot out of it :D . The goal is to set the motor up for an 8-71 blower this winter. I'm hoping for 700 horsepower at the flywheel.
Fevre:
I am almost 100% sure that the 2 bolt and 4 bolt caps are the same, the only difference being that the 4 bolt caps have another hole. All that is needed is to have a machine shop drill and tap for the extra hole on each side.
[Modified by bence13_33, 4:27 PM 6/18/2003]
The motor is far from original :) .... and yes I do plan to beat the snot out of it :D . The goal is to set the motor up for an 8-71 blower this winter. I'm hoping for 700 horsepower at the flywheel.
Fevre:
I am almost 100% sure that the 2 bolt and 4 bolt caps are the same, the only difference being that the 4 bolt caps have another hole. All that is needed is to have a machine shop drill and tap for the extra hole on each side.
[Modified by bence13_33, 4:27 PM 6/18/2003]
Le Mans Master
Joined: Jul 2001
Posts: 9,622
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From: absecon nj
Re: 4 Bolt Main Question? (Fevre)
well me personally have built 4 bolt main motors to run 100+ laps(all season) at 7600 rpm and have never had a problem with main caps(small block)also have built several using milodon splayed conversions using 2 bolt blocks and ran same rpm with no problems.But added insurance id go splayed caps.if your going supercharger and 700+horsepower id go 4 bolt splayed
[Modified by patsnitrovette, 5:43 PM 6/18/2003]
[Modified by patsnitrovette, 5:43 PM 6/18/2003]
Team Owner
Joined: Feb 1999
Posts: 34,447
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From: Republic of Texas
Re: 4 Bolt Main Question? (patsnitrovette)
Shane, yes you can have your block drilled to switch to 4 bolt caps. It is done fairly often here in Louisiana because the vast use of Air Boats (they ALL run 454's and 502's) and 4X4 trucks.
I would think the G.M. 4 bolt main caps would be enough, but then again you can't have a motor biult "too strong". Think about it, how many big blocks in the muscle car era were 2 bolt mains and yet they still held together. I'd spend the money somehwre else but that's me. :D
:cheers:
I would think the G.M. 4 bolt main caps would be enough, but then again you can't have a motor biult "too strong". Think about it, how many big blocks in the muscle car era were 2 bolt mains and yet they still held together. I'd spend the money somehwre else but that's me. :D
:cheers:
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Re: 4 Bolt Main Question? (Corey 68)
I would go with the splayed caps. With what you are puting into the motor it does not pay to skimp on the main caps. 700HP I see more than that by the time you are through with it. Its like buying insurance, you hope you don't need it but nice to know it is there.
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Safety Car
Joined: Dec 1999
Posts: 4,148
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From: Roxbury NJ
Re: 4 Bolt Main Question? (bence13_33)
Yep, I think I would go for the splayed caps if I had the cash lying around, just for the piece of mind, although I can't see you needing them at that rpm. Besides, the pictures on your website of the new bottom end will look way cool with splayed caps. :thumbs:
Le Mans Master
Joined: Mar 1999
Posts: 6,744
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From: delmont pa
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Re: 4 Bolt Main Question? (bence13_33)
i have build BBC with stock 4 bolt setup up to 800+ supercharged HP with no problems. these are boat engines and they take a bigger beating than you could ever give a car engine. :chevy
