301 head gasket

[D Berry]

I've been searching around the net looking for info on the interchangeability of parts between the 301 and other Pontiac v8 engines. I suspect that I have a blown head gasket, it runs fine and doesn't overheat but it does have bubbles in the radiator while it is running. I have found information that all the Pontiac engines 326 through 455 have the same block as far as dimensions are concerned and heads and intakes are interchangeable. He also claims that the 301 and 265 also use the same block dimension wise. Then some folks claim the 301 and larger displacement engines have interchangeable heads and others claim not. One guy says that the heads are interchangeable but then the intake won't fit. Well if the blocks are the same, dimensionaly, and the heads are also, then why is it the intake won't fit. Does anyone know, Please. I'm thinking of getting a pair of heads and having them cut and valves done so I can just swap them with little down time. I thought about just changing the engine for a larger Pontiac v8 but finances are tight and finding a decent running engine around the St Louis south/central IL region has so far proven fruitless, especially since given my health I'll probably have to pay someone else to do the swap anyway. Please does anyone know the real answer?

 

[melsg5]

to determine if you really have a blown head gasket you or a shop should do a engine coolant hydrocarbon test. The kits are available at auto parts stores.
I have no idea where you found information that the 301 is interchangeable. Looking at aftermarket heads and intakes none of them indicate they fit a 301.

 

[cammerjeff]

Your 301 (like the smaller 265) is the short deck block, meaning the block height was cut down. The heads will not fit the "modern" 326-455 engines, also the intake manifold is also unique to the short deck engines, both due to it being narrower, and the fact that the intake runners feed 2 cylinders, unlike the larger engines that have 8 separate intake runners.
The larger engines heads can be put onto a 301, but they require so much modification most people do not think its worth it as you can put a larger engine in for the same or less money it would take to adapt them to a 301.