View Full Version : 2 bolt main w/ stud kit - how much power can it take?

01-09-2005, 02:54 AM
I was just wondering if I really need a 4 bolt main bottom end? or will the 2 bolt be strong enough? Below explains what I have now, and where I want to go with it.

I put together a mild 350 small block chevy several years ago for my 69 Camaro. It has a 2 bolt main with an aftermarket stud kit, TRW forged flat tops, stock crank, stock rods with ARP bolts & polished beams. The top end is an Isky 270 Mega cam, mildly ported stock heads and a Performer RPM intake.

I'd like to swap to some aluminum heads, a roller cam, and perhaps a different intake. And just how much can a two bolt main handle?

Any recommendations on retro fit roller cams? Should I keep the bottom end, or sell the whole motor and start from scratch?

My overall goal is to get over 400 hp and be streetable. If I start from scratch, I'd consider a stroker small block.

Thanks, in advance.

01-09-2005, 03:20 AM
The 2 bolt is plenty strong. They can hold up to around 500 hp without much problem. I'd at least put studs in it for insurance though.

01-09-2005, 05:48 AM
I agree with Allen-for your HP goals, you are okay with a 2-bolt block. I like the Comp Cams retro-fit roller cam kits myself. The valvetrain will be heavier, though-so invest in a quality rocker arm stud girdles-(I assume you have or will be using roller rocker arms, right?) I would recommend having the heads reworked to take better advantage of your roller valvetrain when that time comes.
-opps. I just re-read your post. If you run aluminum heads, go for AFR 190's.

01-09-2005, 11:10 AM
I also agree, I would have stated 500hp as a good point to start looking at maybe a 4 bolt but for your plans a 2 bolt with studs is plenty strong. I myself use a retro fit roller cam and I think it works great. I have enough vacuum and plenty of powerband and can rev to about 6200 rpm without any valve float issues. It is really responsive and I like it. With a roller cam though you NEED to keep it from moving forward and back so use a retaining plate or cam button. And as for recommendation it depends on your car and its use but maybe something from a 218/224 up with good heads, intake and headers will be over 400hp and streetable. AFR heads are about the best you can buy for a SBC and you won't be dissapointed if you do. As for your rotating assembly you 'should' be okay but I believe in overbuilding because it will cost a lot more later if it breaks and you will always have that nagging thought of "oh, I shouldn't rev it or take it to the strip it only has stock rods, crank etc...". The crank should be okay and the rods might be but I would get forged rods if it was mine, however it is yours and your plans for the car will decide what you do. And obviously it will cost you more to get other parts. Good luck with the build!

01-09-2005, 11:18 AM
the 355 in my daily driven sonoma is a 2-bolt with apr studs, stock crank, lt1 rods with arp studs, keith black hyperuetectic pistons, teflon coated skirts.
it is pushing @ 365 fwhp, and really like the 100 shot on top.
need to fix my traction problems @ 70 mph before the 150 jets go in

01-09-2005, 03:27 PM
OK, great! This helps a lot! Thanks!

I do have Comp Cams Roller Tip rockers and the Nylon type guide plates. Should I go with a full roller rocker in this kind of setup?

01-12-2005, 06:34 PM
do you have a part number or link to the nylon guie plates - i have never seen these for a sbc

01-13-2005, 12:02 AM
I'll see if I can find something on it. It's been a few years. I was thinking they may have a Manley product. They were nylon or plastic with a metal ring in the hole where the screw in rocker studs fit through. Anyhow, Johnson Racing Engines, Monrovia did the machine work, and the guy there explained that by using these guide plates, I wouldn't have to spring for the more expensive hardened pushrods.

01-13-2005, 06:39 AM
The rods will give before the block will..

I have Heavy duty X rods in my SBC... with arp bolts and its a two bolt block with ARP studs.. I have seen it hit 8000 rpms several times...(i beat the crap out of it) and still after 5 years its still kickin strong.. Heavy car... and runs 13.0 at 109mph..

as long as rods, pistons, and crank are well balanced it will hold together..