96 3100 Rods

[94GPGTP]

Between the valve seats and between the spark plug and the valve seat. I think its from overheating...due to bad LIM gaskets.

thats where my heads are cracked.. i remember the auto parts store telling me that thats where they are cracked..

[jp_grasshopper_007]

It's worked in the past for my machining mentor.

Cooling the metal will decrease it's size.

I'm not saying dry ice (or cooling metal) won't shrink it. If you have press fit pistons the pin is pressed in the rod not the piston. In that case dry ice will do nothing. The pin and rod will be the same temp.

Any piston you have press or float the pin is not pressed in the piston.

[94GPGTP]

heres the pictures of the cracked heads..

[bszopi]

Try using the MACRO feature on your camera. I can't see anything in those pictures but blurs.

[ForcedFirebird]

I'm not saying dry ice (or cooling metal) won't shrink it. If you have press fit pistons the pin is pressed in the rod not the piston. In that case dry ice will do nothing. The pin and rod will be the same temp.

Any piston you have press or float the pin is not pressed in the piston.

Correct. Cool only the pin, sorry if there is confusion, I'm talking about installation. You can heat the big end of the rod for removal, but even without heating and the right fixture, they can be pressed in and out room temp.

[jp_grasshopper_007]

right-on, we have a rod heater that heats the pin end. then you can push the pin in by hand.

[JohnnyReb]

I did buisness with a well known machine shop for over 20 yrs without a single problem. Two years ago the owner retired and hired a manager. The guy he hired was the manager of a local Autozone. Not one single problem in 20 yrs and thousands of dollars, everything from class 8 diesel engines to my Kohler mower engine. Now a new manager. My first problem was with a head job. Dropped them off with specific instructions to check for cracks and call me if there was a problem. These were Olds 307 Y heads and I just wanted them checked, didn't want to dump any money into them if they were bad. A week later they called while I was gone so I had my wife pick them up. She picked them up and paid my $480.00 bill. Idiots did guides, valves, surface, springs, couple seats and replaced some valves. I let it go, figuring after all those years problem free I'd give em this one. Next I have a 552 forged crank, needs checked and turned. Get the call its done. Go to pick it up and they have a 442, cast, two-piece seal crank in the bag. I say WTF, not mine, not paying and you better find my crank. Now these idiots are sending me a monthly bill and threatening to send it to a collection agency. So yea, mark your parts and make sure they note the casting numbers and any important information on your drop off slip. I now take my stuff to Ohio Crank, at first they thought I was crazy asking for castin #'s, date code and serial numbers if there were any when droppin off parts.