I just started my H.O. 305 that was completely rebuilt. A reputable machine shop bored it, built the stock heads and did all other machine work as well as supplied the overhaul gasket set. They built the short block and I assembled the rest of it. Now it is blowing water out the radiator and seems to have a lot of pressure in the cooling system. When I was assembling it, I realized that the oil pan gasket was definitely wrong so I just got another gasket and went on. Now I'm concerned that the head gaskets may have been wrong even though they looked ok when I installed them. Are 350 gaskets different than 305, and could they have given me the wrong gaskets and that be allowing compression in the cooling system. The engine sounds good but it just belches the water out within a minute. Not getting any water in the oil. Sorry for the long question,but I do appreciate any advice. Thanks I am aware of the difference in bore and all of that looked fine.

 

i'd suspect all SBC head gaskets interchange, but there may be a few that don't. i'd leak it or do compression test to see, also might want to do exhaust gas test, however i tihnk you have a good idea what the results will be.

 

Thanks for the reply. I did a little work to get all the air out of the cooling system,and I think that is going to help quite a bit. It still seems to push a little water out when I shut it off but it isn't blowing it out like it was.The radiator looked pretty clear but it may need some cleaning.Thanks

 

seems like every time i fire a new engine,it does the "whale blow"!
this is because there is some air left in the system and the areas where there is air get no coolant.this is usually high on the cylinder walls.as the coolant expands during engine warmup,these areas boil the coolant even at 50/50 mix!the best thing i can think of is to pressure bled the system bfore startup of a "dry" motor.second best would be to cycle the waterpump at 1000 rpm or so for awhile to bleed the system of air.kind of like priming your oiling system.
y'all got a way to do it?
Eric

 

I drill a 1/8" hole in the thermostat. This allows the air to vent as you fill the engine from the radiator. The hole makes no noticible change in cooling performance from my experience