i have rebuilt a 97 lt1 motor for a friend , it is running but blows coolant out of the radiator fill and if i put new cap on builds enough pressure to open cap and over fill over flow bottle. everything is new , pump included. but i remember 1 head gasket in his kit was bent so i grabbed a set i had on the shelf and installed the heads. the gaskets i installed were for an older style 350 say 86. could this be causing the overheating? i found 2 different part #s for lt1 gaskets and older gaskets. please can you help , what is different between the 2 sets? do i have to pull the heads off [oh no]. or what else could cause this? tom

 

Those non LT1 head gaskets will definitely honk up the cooling. Putting the steam line hose on the overflow nipple that comes out below the radiator cap and the overflow hose on the nipple in the radiator end cap will also cause the symptoms you listed.

 

Yes, you have to pull the heads again. The LT1 head gasket is LT1 specific because of the reverse cooling. The cooling passages are different than a SBC.

 

thanks guys thats what i was afraid of. what a bone head move huh? tom

 

Everyone makes one of those mistakes from time to time. (If anyone tells you otherwise, they're lying)
No big loss other than some extra hours of work to cement into your mind
that you'll never make the same mistake again LOL