To balance or not to balance

[Joe Ricard]

What does everybody thnk about have the crank, rods, along with the flywheel/pressure plate balanced. Does anybody know how close of a tolerance is good for a street/autocross car.

[Dave at Pelican Parts]

Balance that mother! Individual parts (pistons, rods) should be within 1 gram of each other. 0.1 grams for a race car. Not sure what the specs on the dynamic balance are, but it's good to have that done too.

When the parts are in balance, the engine spends less energy "fighting itself". That will free up more power to drive the wheels. It will also stress the parts less, and tend to make for smoother running. The engine will tend to last longer.

The only time you don't want too balance the moving bits are when the time/effort/cost of doing so is out of your range. For example, if you do a clutch job and find your flywhheel is badly worn but the rest of the motor is fine. Then just replace the flywheel and don't bother with tearing the whole motor down just to get the balancing done.

--DD

[Jim Smolka]

I agree with Dave, balance that motor!

Going through the math reveals that a little static weight unbalance translates to a bunch of rotating weight when the motor is rev over 5K RPMs

[Bleyseng]

Boy, How can you even consider not balancing the motor.
I totally agree with DD and Jim.
Have everything that spins balanced including the fan pulley! It really does make a difference and it's only a few bucks compared to the total cost of rebuilding the engine. This is not the place to save a few bucks...
Geoff

[Joe Ricard]

What a silly question anyway since I really knew the answer. How ever not the tolerance (thanks Dave). Going to visit my local speed shop only builds V-8 race engines. Maybe I can get him to squeeze me in.
Good thing you reminded me about the fan! now that I painstakenly cleaned all the crud out of it sandblasted the whole thing I am sure it reduced rotational wieght. he he.
Guess I will be yanking that sucker tomorrow.
NO SENSE IN ONLY HALF WAY DOING A JOB.

[MASSIVE TYPE IV]

I don't build an engine unless it is fully, dynamically balanced....I just spent almost 30K on a new balancef for the shop, thats how much I believe in it...

[Joe Ricard]

Called everybody in the phone book. Mississippi Gulf Coast. Most wouldn't do it. Some would do it but weren't sure how. One guy wanted to know why? All of them got a Thanks alot and a dial tone.
Jake got your web site on my favorites so when PP delivers all my Xmas engine stuff I may be giving you a call. What do you all need? crank, rods, flywheel, pressure plate, fan, pistons. ? ?????friction disk? Sorry, do you do this? or only make complete AWESOME motors.

[MASSIVE TYPE IV]

Sure, send the goodies to us, we need everything including crank gears, hub fan, pressure plate, flywheel, rods, crank and even the flywheel bolts to do it right..