Floating pins in gen III rod?
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Floating pins in gen III rod? I bought the 4.8 flat top pistons / pins / rings below To put in a LM7. The Original wrist pin I pressed out of the Gen III rod is 0.945 but the pins the kit came with is 0.943. The Original 0.945 pins will not fit the pistons, the 0.943 Pins that came with pistons push through the gen III rods without issue and move freely ( no need to press or heat rods) like a floating pin. What is the harm in running this?
I understand steel on steel is not ideal, I have read that the rods should be bored and have bronze bushings pressed In and a oil hole drilled. But having that work done would bring me close to a new set of (gen IV) rods. And will those work with theses pins. If I just run it and it galls and the pin freezes in the rod, what Harm would that be?
https://www.ebay.com/itm/223720928176
I understand steel on steel is not ideal, I have read that the rods should be bored and have bronze bushings pressed In and a oil hole drilled. But having that work done would bring me close to a new set of (gen IV) rods. And will those work with theses pins. If I just run it and it galls and the pin freezes in the rod, what Harm would that be?
https://www.ebay.com/itm/223720928176
TECH Senior Member
Joined: Jun 2016
Posts: 22,295
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From: Central Cal.
You would need clips in the pistons to keep the pins from hitting the cylinder walls. Are there grooves cut in the pin bores in the pistons?
I just checked the eBay ad. It says they are full floating pins, and the pic shows circlips as I mention above. Looks like you're set.
I just checked the eBay ad. It says they are full floating pins, and the pic shows circlips as I mention above. Looks like you're set.
Steel on steel is ok for a mild to moderate build. The beauty of a bushing is to absorb shock from detonation and the fact that it’s a dissimilar Metal lessens the chance of galling. Similiar metals will gall before dissimilar metals will. Detonation is the enemy of a non bushed rod, so have your tune right. You need to know the pin to bore clearance. Don’t assume anything here, just going by advertised numbers. You want to see .001 to .0015 clearance. Too much clearance isn’t good, but it’s better than being too tight. The pins rely solely on splash oiling only, so this needs to be right. Personally I’d like to see the pins coated if it’s going to be a non-bushed floating setup, but the import engines have run non bushed, uncoated pins for gazillions of miles.
Regarding your question about the harm in them galling together, the galling process will produce mega heat and put potential metal particles in the engine. The pin will get so hot it will deform the bore in the piston also causing a potential galling issue there also. I’ve torn engines down that had severe galling so bad you couldn’t rotate the piston on the rod. It was totally seized. Destroyed the cylinders. The pin end of the rods had gotten so hot they had turned blue.
Regarding your question about the harm in them galling together, the galling process will produce mega heat and put potential metal particles in the engine. The pin will get so hot it will deform the bore in the piston also causing a potential galling issue there also. I’ve torn engines down that had severe galling so bad you couldn’t rotate the piston on the rod. It was totally seized. Destroyed the cylinders. The pin end of the rods had gotten so hot they had turned blue.
