Re: V8 Pistons

Posted by gone1951 On 2008/8/25 23:09:14

I've only rebuilt 4 engines ( not very many by any standards ) A 4 cylinder model A engine two 6 cylinder Chevy's and a 1955 olds V8. I didn't have any of them balanced in fact I didn't match weights of anything. Just installed the new pistons in the holes and ran with it. All the engines seemed to run fine. Just like they did before the overhaul. I even changed one rod in the olds because the old one bent when the valve broke and wrecked that cylinder. I was always under the impression that balancing was for the racing engines. Ones that had to turn 8 to 10K but for normal freeway cars it didn't make much difference. I have been told by people that their engines were balanced and to quote them "they really ran smooth and don't vibrate". Question would be how do they know at 60 MPH it wouldn't have been just as smooth unbalanced. I don't know but Id bet that when GM or Ford build their engines the rods, pistons and pins come out of a big pile with no more care than the weight tolerance when the parts were manufactured. The cranks are balanced but I think the crank alone has most to do with balance then the harmonic balancer and the flywheel. The small variation in piston and rod weights has little effect. Someone compared the rotating weight to the reciprocating weight and said that the rotating weight is what is important. I agree with that.