Just got the 350 block back from being line bored, honed, balanced, rods rebuilt and polished with ARP bolts.

Now I stumble onto the fact that alot of people run ARP Main Studs for better strength over the factory bolts.

I suppose that the only way to run the studs would be to have the mains line bored again?

Am I safe enough with the factory bolts? Machine shop seemed to think I could get 450 flywheel and shift just under 7000rpm and be fine with good oiling.

Thanks
-Paul

2 bolt or 4 bolt?

I was just in the same situation. I'll be starting my engine soon....should be around 400hp or so....i'll let you know what happens. I assume your's is a 2 bolt. ?

Yeah sorry, it's a two bolt. The first time I built it I didn't know anything... didn't balance, didn't line hone, didn't rebuild rods, etc.

Thought I did everything right this time and then find that!

Originally posted by Twilightoptics:
Just got the 350 block back from being line bored, honed, balanced, rods rebuilt and polished with ARP bolts.

Now I stumble onto the fact that alot of people run ARP Main Studs for better strength over the factory bolts.

I suppose that the only way to run the studs would be to have the mains line bored again?

Am I safe enough with the factory bolts? Machine shop seemed to think I could get 450 flywheel and shift just under 7000rpm and be fine with good oiling.

Thanks
-Paul =
Paul,
There is a little more to it than "450HP & 7000 RPM"
You can very probably change the bolts to studs but you will not know until you try. Chances are you will not have a problem.
Nothing against your engine builder or you but I find most HP numbers tend to wind up a bit less than expected :D
HP in itself is not the biggest determining factor in block strength.
I feel number one is DETONATION a real biggie.
Then the balance needs to be right followed by the rpm, stroke & weight of parts used.
If it is truly about 450HP & under 7000 preferably about 6500 you should be just fine with a properly prepared 2 bolt block as long as you don't detonate it.
I would invest in set of studs, put them in & measure the bores & bearing clearances.
Chances are they will be fine.
No question I would prefer a 4 bolt for your application but I have done a lot of 400-500HP 400's with no issues at a reasonable RPM level ;)

The engine builder didn't say I would make that 450, but he said I wouldn't have a problem structurally at that level. I just ordered a Lunati/Harold cam which they say should make power to 63-6500.

This is a fuel injected setup, so detonation will never make it to the audbile level as the knock sensor will retard timing.

Realistically I'd like to see around 330-350 at the wheels. After finding all the problems there were taking this one apart (Valves not sealing, lots of oil consumption, no balancing, some exhaust leaks, and more) It put down 264 to the wheels that way. Now all those problems are taken care of and there is a cam much better matched to the combo.

Thanks for the replies!


Edit: Machine shop said yeah it's a good idea to use studs, and that since I had it line honed already there shouldn't be a problem. It's not like rod bolts where they are pressed in. The Main caps fit in there and the studs/bolt just clamp down. Whew! ARP STUDS HERE I COME!

you'll notice if you look carefully that the factory bolts are necked down so as not to touch the insides of the bolt holes in the caps. The stock main bolts do not locate the caps, but instead just provide a vertical clamping force. All of the aftermarket studs I have seen so far are full diameter for the full length. This means that the studs may hit the insides of the bolt holes in the caps and serve to locate the caps. Also, if this is the case the studs are subjected to shear forces (side loads) that are not part of the basic design of the SBC. Really, the block should be align honed with the studs in place. This also helps compensate for the increased clamping load supplied by the studs if they are torqued to the same values as the bolts.

You might try this approach: install the bearings and crank, torque the caps down with the bolts as usual. Then, one at a time remove a bolt and install a stud. use a little oil on the threads that screw into the block. If you can screw the studs in with your fingers, no binding, you might get away with changing out the bolts for studs after the align hone. If any of them won't go in stop, go back to the bolts. Keep in mind that most of us who have been building engines for many years have never seen an engine failure caused by the stock chevy main cap bolts. You will also need to verify clearances with the studs torqued down, it may be different than with bolts.

All in all,if it were mine and it had been align honed with bolts I would just run them, they are not a source of problems, never have been.

Tom

I have a slightly used set of ARP 2 bolt main studs if you want to try them..if you find you can use them..you can buy me dinner..if not send them back

Tom, I just went out and looked at my main bolts. The top 1/2" of bolt just below the head, that goes into the main cap... is the same size as the main cap. The body below that is thinner as you indicated. These are the bolts that the machinest used when honing and such, so I think I'll take your advise and see if they thread in easily.

Would indicate though, that it should be pretty close.

Thanks Big Jim but I already ordered them from summit for $35. Cheap enough for a little insurance eh?