stock crank, internal or external balance? i am going to get my rotating assembly balanced, and am kind of confused.

the downside is i dont want to take the crank out of the block because i have already torqued it in and couldnt untorquing ARP bolts make them fail?

 

Depends what engine you're talking about. I'm going to guess and say it's your 1985 350. That's an internally balanced crankshaft.

You can reuse ARP bolts as many times as you want. They're not a torque to yield bolt. If there was something critical about reusing them, a stretch limit would be provided. If the bolts are stretched beyond the limits, you throw them out.

You need to take everything out of the engine to get it balanced. They're going to want crank, rods, pistons, wrist pins, rings, rod bearings, rod bolts/nuts. A good balance shop will also want the balancer and flexplate even though the engine is internally balanced. Even a neutrally balance balancer and flexplate can be slightly out of balance.

 

the engine is a 1972 357, which i am piecing together and they were all the same prior to 1987 (right?).

i guess the reason i thought of that about the main bolts was because the rod bolts had a stretch limit on them.

what would you think money wise for a decent balance. i was quoted $350 for an internal at a reputable machine shop. i guess i will have to drill the machinist some more.

one more question... do i have to put the rod caps back on? i had one heck of a time getting those off after the bolts were pressed in.

 

The 400 is externally balanced. Typically a 383 is also externally balanced because it uses the 400's crank. Any externally balanced engine can be built internally balanced with an aftermarket crank. All the other old style SBC engines are internally balanced.

The rod bolts have a stretch limit but only when torqued down. They need to be measured before use to see if they've stretch at all the next time they're removed. Normally they can be used many times unless they go through severe abuse such as in a high HP race engine.

Cost of a balance will depend on how much work is needed. If the rod and piston weights need a lot of adjusting, that's extra. If a heavy mallory weight needs to be added to the crank, that's extra. I think when I got my engine done, it was around $500 just to balance everything. It was spun up 12 times to get a perfect 0.00 gram balance on both planes.

Keep the caps matched to the rods.

 

never had an engine balanced - how do they do it if they dont have the block - or do they use a setup block and spin from there?

 

To balance the crank you spin it in a balancer, not in a block.

 

Google is your friend

http://www.carcraft.com/howto/ccrp_0...ing/index.html