As I have said in a past posting, I bought a short block 350 for my vette. My question is, Will it affect my crush on my bearings or alignment if I swap out the old GM main bearing bolts for the stronger ARP bolts? I am going to try to push this engine past 400 hp and 400 torque and I would like the peace of mind. I figure if I do it one bolt at a time and torque them properly I should be fine, but I decided to ask you guys first. P.S. The block is a two bolt main. Thanks guys.

Not at all. ARP bolts are MUCH better than stock. Make sure you torque them properly though, the torque procedures on them is different. Not sure what it is, but i'm sure KStyer or BigFish could help you out with the correct procedure for ARP bolts.
I'm confused about the "one bolt at a time" portion of your post. If you're replacing any of them, you need to do them all at the same time. That's probably not what you meant by it, but figured i'd throw that out there just in case!

Sorry, I ment, remove one bolt then stick the arp in.. torque, remove adjacent bolt..stick next arp in... torque. Just so the bearing is not loosed and could throw off the blueprint job I paid for.

|UPDATED|1/25/2004 10:59:50 PM (AZT)|/UPDATED|

Just my opinion, but if you are planning to go with that much power you might consider having a girdle installed. Your 2-bolt mains will handle it for a little while. There is a great machine shop in St. Charles that would be happy to do it for you.

Big Fish,
What's a girdle?

A girdle is a one piece unit that attaches all of the main bearing caps together. It make the bottom end stronger. And I agree, with that much power it would be a good idea.

As for one bolt at a time, bad idea. You want to loosen and tighten both bolts on a main or rod evenly, side to side. If one side is tight while the other is loose, the cap can shift and mess up bearing alignment. Just do one cap at a time and you will be fine.

The ARP bolt is a torque to yeild bolt and is tightened based on the design of the specfic bolt. With any bolt, set the cap in place and snug the bolts evenly. ARP bolts usually give you a starting point to set with a torque wrench. Then it gives you a specfic number of turns. It may do this is several steps. First one bolt then the other. Get the specfics from ARP when you buy the bolts. They may not be stronger then original bolts, but they are much more accurate in clamping force, which is really what you want. This keeps the bearing at just the right crush and tension. That way they work smoother and last longer.

Ken Styer

Ken gave a great description of what a girdle is. It will add strength to the bottom end so you won't have any problems. I believe there are other methods as well, the machine shop in St. Charles could answer any questions about the "other" methods better then me. My guess is your engine will be very short lived without doing something to beef up the bottom end. To see the kind of horsepower and torque you are talking about you will probably need to build it to run at 6,000+ RPM. Another option would be to sell the 2-bolt block you have and buy a 4 bolt block, problem solved.

|UPDATED|1/26/2004 2:52:45 PM (AZT)|/UPDATED|

Thanks big fish and kstyer for the exellent advice. Would the engine need to be disassembled in order for the stud gridle to be installed? I have read in several books that the two bolt main block is very under rated for its strength. The engine is going to be for daily driving and it will rarely see above 6000 rpm. Let me tell you what I am planning to do. The heads are older trick flow twisted wedge heads. the pistons are TRW forged flat tops with four valve reliefs. 9.7 comp with 64 cc heads. the rods are gm with ARP bolts. the cam I am planning on using is the comp cam 280H magnum. my desk top dyno estimates around this range of power but I expect lower due to the desk top dyno's ideal conditions. Big fish, what is the machine shops name? Thanks again for the help.

Guys,
couldn't he also go with a splayed cap? he wouldn't have to swap out his block and he'd get the extra strength you mentioned.
Hank

Splayed bearing caps would work too. I sent him an e-mail last night to that effect and the machine shop info. Either way, cost begins to become an issue, and 4 bolt blocks are not all that expensive. You can practically buy a crate motor with the kind of performance he's looking for, BRAND NEW with factory warranty for less then you can build one for.