Junorocket

Hi,

Recently I bought rotating assembly kit for my LS 6, which consist of 3.903 Wiseco, Lunati conn rod, and K1 crank, got them balanced, packed and shipped to my home country, Indonesia.
And sadly that's the end of the happy story.
The problem began when I brought it to a machine shop to get the block honed, the machinist misinterpret the piston card, and I ended with 3.9065 wide cylinders.
Wiseco's requirement for PTW clearance is .0035, with my 3.9065 bores it put me at .007 PTW clearance, which too much.
I'm thinking to replace the pistons with 3.908 Mahle, however, from my search, I read that their advertised weight is 398 gram while my 3.903 Wiseco weight 446.20 at the lightest, that is almost 50 grams gap.
And here in Indonesia, unfortunately, there's no machine shop that could rebalance my crank.
Does any of you guys have use 3.908 Mahle and could confirm the advertised weight is correct?
Do you guys have any advice on which route I should take regarding this matter?

Thank you.

KCS

iTrader: (20)

You may be able to match the weight with a heavier piston pin. You can get pins with a thicker wall, but I’m not sure how much weight that will add.

Junorocket

Thank your for your response.
My current pin weight at 131.40 grams, in order to match the weight, assuming that Mahle advertised weight is correct, I need to get 180-ish grams of pin right?

Another thought, what if I get 3.905 Wiseco piston, that is .005 PTW clearance there, and maybe, just maybe, with some coating job on the pistons I could get away with .004 PTW clearance, will that work in this situation?
Coming from same company I know the weight gap between those two will be so close for me to be able to work with it.

Ordering & balancing another crank is my last option, the shipping cost is killing me.

Summitracing

Piston coatings (when done professionally can add close to .002 per skirt versus the .0008 in. that comes on the skirts of the Wiseco's currently. Do you have the capability to get those done in Indonesia? It must be done correctly to maintain the heat treat and masking is critical. Here in the USA, Polydyn in Texas and Calico (North Carolina) are two companies with a lot of experience that do nice work.

Junorocket

Summitracing

Yes. This is actually a common occurrence. Just tell them you would like the piston o.d.'s to be increased to 3.903. That is a coating build up of .002 per side and will net .0035 net clearance as intended.

Junorocket

Summitracing

No problem. We have many international customers, so this isn't the first time we've run into the conversion problem.