Engine Balance Question

I Am Trying To Locate A Machine Shop In Jersey That Will Balance My Rotating Assembly With The Pressure Plate. Everyone I Call Keeps Telling Me That It Does Not Need To Be Done...what Do You Guys Think? This Forum Was The First Time I Heard Of Balancing The Pressure Plate To The Fly Wheel. Thanks!

definitly have your flywheel clutch and harmonic balancer all balanced at the same time. they can all have slight variations that lead to high rpm vibrations that are really hard on engines. My machinist insists that I bring him the flywheel clutch and the balancer when im having stuff balanced.

Agreed. My machinist also balances everything from the pressure plate to the pulley and spots paint so I can reassemble in the same orientation. The difference from stock or typical builds is noticeable. If I put it in neutral and spin the engine up, I can hear the engine racing, but don't feel anything. Nice.

David

"Everyone I Call Keeps Telling Me That It Does Not Need To Be Done"

Yeah, it doesn't need to be done by some shop's standards. I had a local shop tell me my block didn't need to be line honed either. I left and found another shop. It's very frustrating until you find the right shop.

BTW, I am sure you saw the article on the home page? Combine that with the replies above and you've got your answer. Good luck out there.

So when you put in a new clutch you have to pull your engine apart and have it rebalanced? How about the pulleys and balancer when you replace them?

The 347 I got from Woody runs pretty smooth. Maybe I got lucky.

Originally Posted by retyler

So when you put in a new clutch you have to pull your engine apart and have it rebalanced? How about the pulleys and balancer when you replace them?

Funny guy! Seiously, if you take the old one in they can match the balance, or you can provide the balance spec's and it will be duplicated. My machinist gives me a list of all the parts and their final weights and balance factor. So, I know my pistons were all weight matched at 434.5 grams and my clutch, pressure plate and pulley are zero balanced, etc. I use a paint pen to mark the numbers right on the parts for if I lost the paper. I've seen some machinists engrave the spec's right on the parts with an electric engraving pencil. Whatever works for them and you.

Speaking of 'is it necessary', I was very fortunate to get a part-time job with a professional racer as a kid. I wasn't allowed to use the machinery and power tools, but did the mundane work they needed done but would be better doing something else. For example, they supported a bunch of cars including a Stock class '67 Nova with a straight 6 engine with all factory parts as required by the rules. They gave me a 5 gallon bucket of rocker arms and I had to measure each one for ratio and mark it on the side with a diamond scribe. Due to production tolerances, this produced one set of stock rockers that were above average ratio, giving greater valve lift and all exactly the same. If you wonder how a stock 6 cylinder with all factory parts can run 11's - that's how. It's all in the details.

Is it necessary? No, it will start and run without most of the details. After that it's pure luck and compromise.

David

Thanks guys I agree. A 7000 RPM 331 stroker street motor may never give me problems, but I like the idea of a 7000 RPM 331 stroker with 200,000 miles on it and still running Like new. My Father taught me growing up "Do it right do it once" and while you may never have time to do it right the first time you always have time to do it right the second time. Example I am building this 331 because I didn't think I need to check piston to valve clearance...I was wrong... destroyed all my pistons broke one valve cracked block. only thing not destroyed is the cam. this time its all the way right. I just have to find a shop that balances correctly. Thanks for your help.

You guys crack me up. Alot of you guys seem to look up highly to joe Sherman, ask him about balancing as he has built a ton of excellent racing engines. Ask him what gram tolerance he is ok with. On the flipside, I dont know if you guys have ever played with a high end crankshaft balancer before but I play with my hines balancer everyday, they are the top of the line balancer money can buy bar none. I can balance an external crank using the customers flywheel and harmonic balancer. Get it balanced within .02 grams on both planes, I can then just loosen the flywheel bolts move the flywheel .100 thousandths of an inch either direction then retighten the bolts, respin the crank and it will be off 5 grams on 1 of the planes.

So moral of the story make sure you bolt your flywheel or flexplate back on the crank in the EXACT same position that your machinist did when he balanced it originally. AINT GONNA HAPPEN......

Ever been in a brand new mustang? I got 2 stock 302 rotating assemblies I balanced for some baseline testing, ya they are out 20 grams in the front and 18 grams in the back from the factory and miraculously that junk lasts 200k miles LOL

I agree. I actually balance all the components when I can, but I sure wouldnt lose sleep over not doing the pressure plate.

I have to ask though, why are guys fighting you to do it?

Generally I just do the whole assembly less the clutch, then get it to match

Maybe communication issue with them? It sure doesnt add much work

I would almost recommend NOT doing the pressure plate. I had mine balanced as per the shop's recommendation. Put the motor together, got it in the car, and had clutch chatter like none other. When they welded on it to add weight, they warped the pressure plate, making my couple hundred dollar clutch kit junk. You could visibly see from the wear pattern that it was warped at the same exact spot that they welded on the pressure plate. On top of that, they refused to to make my situation right by providing me with another pressure plate or a bit of a refund. Probably just a bad shop, but for such a minute detail, I don't think I would chance the trouble involved again.