Main Cap Stud Question

Old November 14th, 2017, 06:09 PM
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Main Cap Stud Question

Hi All,

I've been doing some reading through Bill Trovato's book and he says that the main webs on Olds gas blocks are weak and eventually, under too much power, the caps walk and eventually fail. He recommends a main cap girdle, but I'd like to avoid the cost and modifications involved. Can I throw on a set of ARP studs and rest easy, or is a girdle the way to go? I'm not trying to make crazy power, I just don't want to run over my crankshaft if I try to throw nitrous at it.

As always, any and all info is much appreciated!

P.S., if you have tried and true combos for a 350 or 455, I'd love to hear about them!
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Old November 15th, 2017, 04:33 AM
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Hp? Rotating assembly being used? Engine size?
You're being pretty vague.
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Old November 15th, 2017, 05:33 AM
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Throwing nitrous is a good way to get a vertical torque curve, and that is very hard on the block.
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Old November 16th, 2017, 07:00 PM
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Rotating assembly would be stock crank (or Eagle for a 455). Better rods (haven't done any looking yet) better pistons (haven't looked). the goal would be streetable 450 with a 350 and closer to 650 for a big block. has anyone gotten really crazy with a 350 and made more than 550 with one?
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Old November 17th, 2017, 04:52 AM
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My stroker small block should make 550+, I'll keep you posted on that.
If you're trying to make 650 with a big block you'll need either an aluminum rodded rotating assembly, or halo and studded mains, H beam rods and a good forged piston. Otherwise you'll have parts all over the street.
My small block has a 1/2" 5 main halo with studs and happened to have excessively thick cyl walls as compared to other gas blocks I've had checked.
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Old November 19th, 2017, 10:37 AM
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And that's NA right? Would you trust it with any sort of boost or nitrous? Basically my goal is to not have to use a halo or any sort of girdle, they're kind of expensive and need mods done to the oil pan, unless i'm mistaken. i know no power comes cheap, but i'm just trying to see how realistic making power with an Olds block is without a girdle
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Old November 20th, 2017, 06:26 AM
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Originally Posted by Bobby455 View Post
i know no power comes cheap, but i'm just trying to see how realistic making power with an Olds block is without a girdle
Which pictures of mine would you like to see, the ones where it broke the crank into 2 pieces and ripped out #4 main bulkhead, or the ones where it broke the crank into 5 pieces and ripped out #2, 3, and 4 bulkheads? Or, I can show you the pictures of the 2 girdled blocks that each had a failed crank, but no damage to the block in any way.
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Old November 20th, 2017, 06:48 AM
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Originally Posted by botmbulb View Post
Which pictures of mine would you like to see, the ones where it broke the crank into 2 pieces and ripped out #4 main bulkhead, or the ones where it broke the crank into 5 pieces and ripped out #2, 3, and 4 bulkheads? Or, I can show you the pictures of the 2 girdled blocks that each had a failed crank, but no damage to the block in any way.
Couldn't have put it better myself.
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Old November 24th, 2017, 06:46 AM
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what sort of power were you making with that motor though? did it have a power adder?
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Old November 24th, 2017, 01:08 PM
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Originally Posted by Bobby455 View Post
what sort of power were you making with that motor though? did it have a power adder?
Between 530-550 HP, running 10.60's-10.70's @ 123 and weighing 3450 lbs., no power adder, footbrake launch.
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Old November 25th, 2017, 05:11 AM
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Originally Posted by cutlassefi View Post
My stroker small block should make 550+, I'll keep you posted on that.
If you're trying to make 650 with a big block you'll need either an aluminum rodded rotating assembly, or halo and studded mains, H beam rods and a good forged piston. Otherwise you'll have parts all over the street.
My small block has a 1/2" 5 main halo with studs and happened to have excessively thick cyl walls as compared to other gas blocks I've had checked.
Mark, who's Halo are you running? You have probably seen a few, I know a few Olds specialists carry them. I will be needing a 5 main 1/2" Halo and what ever studs are needed with it when I send my 403 block in to be machined . I know the caps need cut, what .100"? and an align hone is necessary? I will be contacting you for another cam and other parts to finish this 424ci stroker. I would like to get the short block done by next Summer. I think your knowledge on what needs done to run a girdle will help this thread.
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Old November 25th, 2017, 08:17 AM
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I've always used the 1/2" J&S stuff, good quality and fair price. But I know there are other good ones out there.
Not sure how much he cut the caps but just enough to make them flat all across the top. Yes align hone is mandatory at that point.
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Old December 4th, 2017, 12:29 PM
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J&S supplies the dimensions needed to install his 5 main halo, basically the front 4 main caps are cut to be the same height as main number 5. Align hone main bores at a minimum, might need an align bore if factory cut is not straight.
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Old December 26th, 2017, 07:53 PM
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On the j & s 5 main,have #1-4 mains milled to 2.500 and he provides a couple washers that install between the girdle and the #5 main to provide the proper fit.
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