Do you have to bore when swapping pistons?
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From: North Bay, Ontario
Do you have to bore when swapping pistons? I have an LQ4 block and have purchased lq9 rods, pistons and rings standard size. The machine shop is telling me its common practice to bore and isnt looking good for what i have sent to him. He has not looked at my motor yet. WHen i had it the cylinder walls looked good with cross hatching still there. Will i be okay?
Is there something wrong with the block? If there is nothing wrong, he should just be able to bump the hone through the cylinders and be done with it. You only need to bore it if the cylinder is REALLY messed up or you want to go to a significantly larger piston.
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If what you say about the cylinder walls is true I wouldn't have sent it to a machine shop at all. I would just hit it with a ball home and call it done. It sounds to me like be wants to do some stuff to make more money.
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From: North Bay, Ontario
I need to get the rotating assembly balanced because my crank is along crank from the early year truck 6 litres so I have a crank out of a Camaro and lq9 pistons and rods. Last motor I built had a bad vibration so I want to be sure
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From: North Bay, Ontario
so i talked to my machine shop, they say the block is out of round 2 thou. So now the standard size pistons and rings i bought wont work..... any ideas on what to do now?
Bore to the next oversize, buy new(or used) pistons and balance the whole assembly. Make sure the machine shop uses torque plates so the bores are nice and true and slap that beast together.
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Buy new pistons and have them bore the block, after they show you with a bore gauge that it's out of round. I would have them show me that it's bad before i ordered anything.
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.060 over bore on a 6.0 block ? I thought .030 was max ? Tho with sonic testing, some could go larger depending on core shift.
That cam you have will not be optimal for the LS3 heads.
If you want to do it right, get a custom grind, or a known good grind for the LS3 heads.
That cam you have will not be optimal for the LS3 heads.
If you want to do it right, get a custom grind, or a known good grind for the LS3 heads.
Most people believe the LS3 needs a good 8-15* split intake duration to exhaust duration. The only thing I could think TSP was thinking was an aftermarket LS3 head with a better balance between intake and exhaust flow. My LS3 comp cam has a 16* split (219-235). It would be a good grind for my mild setup if the lobe sep was tighter than 113 for my single plane carb intake.
Most of what I have read claims the exhaust flow should be at least 70% of intake flow to run a tight split on the cam. A stock LS3 head is closer to 65%, thus the wide split.
Most of what I have read claims the exhaust flow should be at least 70% of intake flow to run a tight split on the cam. A stock LS3 head is closer to 65%, thus the wide split.
