Ok building LQ4 with Ls3 heads, just got new Mahle l92 Pistons and Lunati Voodoo Hbeams. I talked to my machine shop and the guy said that he can balance the engine for $175 but only needs Crank,Pistons and rods.

Is this right or does the harmonic and fly wheel also need to be Balanced? Reason I ask is because he was very unsure and need to know if I should find another shop to do this service?

Thanks for the help guys Ls1tech rock

 

When I had mine done/ my machinist balanced all rotating parts and that included the pressure plate, flywheel and balancer.

 

Thats what I would think and with him not knowing its making me a little worried. He was unsure as he said its internally balanced.

I also dropped off my heads and asked how much to mill off Ls3 heads and He said he doesn't know and would have to wait for his employee to get in on Monday as hes the LS guy.

 

Most likely the rods will balance within 1-2 grams on both the big end and total weight. Quality pistons should also weigh right on so no grinding or drilling. These pieces along with the rings/wrist pins/retaining clips and rod bearings are all needed to weigh them in order to make up the bobweights.
Then the weights get bolted to the crank which gets spun and either drilled or mallory (heavy metal) added to correct the balance. Then some more thorough shops will also individually mount the balancer/pulley and rebalance as well as bolt the flexplate/flywheel on and balance for a final time. This insures that everything is happy and not trashing your bearings.

 

You don't need or want to balance the crank with the damper and flywheel. It's an internally balanced engine, so it's done without.

 

True but doesn't that assume that the balancer and flexplate are perfectly
balanced. I know you've done a few and sometimes they can be off by a bit.

 

You're right, but you don't want to balance the crank that way with them on. If you change the clutch and flywheel and it doesn't have the same imbalance as the old one, then it will throw the balance of the crank off again.

I balance the crank, and then the flywheel and clutch separately to make sure they're zero balanced. If they don't have any imbalance to them, then they won't affect the balance of the crank.

 

Do you guys really want to have to rebalance the whole rotating assembly everytime you change the clutch? If not, then balance the rotating assembly on itself and the rest of the rotating stuff separately.

 

Thanks for the reply's, Makes sense what is getting said. Ill bring everything and just ask him to check the Fly and harmonic by themselves.

 

We're thinking the exact same thing....I'm not saying to drill or grind on the crank after putting the balancer and/or flexplate on but rather use the crank
at that stage of the game to just fixture each piece. Obviously removing the
weight from the balancer/flexplate so that either could be removed/replaced
without disrupting the crank assembly....common sense for sure.