Ron and others,this is a 261 Chevy project.I trying to figure the best way to get the piston near zero deck clearance at TDC.The GMC rod is .19 inches longer than a Chevy rod and I was trying to find a combination of an inexpensive flat top piston from another engine that might work with the GMC rod.Doesn't seem to be any that will get the piston up there.And from what i see the so called Caddy 261 leaves the piston down the hole with no proper quench.A set of 500 buck custom pistons is not out of the question so I thought using GMC rods will at least move the piston pin up higher and make use of the full floating small end bushing in a .990 size.
I read you can machine a GMC rod thickness to fit the Chevy (1.240) If the GMC rod is 1.4 then that's a bit to machine down and will likely mean I have to trim the sides of the GMC connecting rod bearing to fit properly.Or maybe the Chevy crank jounal can be machined slightly wider.I haven't seen a GMC rod in awhile so I can't remember if the bearing shell is a lot narrower than the rod.I could also recut the locating tabs if necessary to fit a 261 rod bearing if the outer diameter is the same as GMC.The bearing crush will hold the insert in place.
One more thing,stock replacement oversize 261 flat top pistons sit .060-.070 below the block deck at TDC.I built a 261 15 years ago and had the block decked .050 to at least make an attempt to get the quench reasonable.But with a typical .050 compressed head gasket somethine near zero deck might be better.I'm not sure that decking .060 is a good idea on a block with at least a .060 overbore.
Obiviously,clearance notches for the intake valve is probably necessary
