My 305 is a 350

American Muscle 79

Jan 29, 2018
San Diego, CA
Happy New Year, everyone.

I recently scooped up a 79' El Camino with a 305. It was in running/driving condition when I picked it up, but it had a good amount of leaks. It was also an absolute dog when it came to performance. I believe I clocked 0-60 on the freeway onramp at 11+ seconds.

This winter I decided to pull the engine so I could install new gaskets and maybe put a little cam in it. Though I didn't think it would help much, given the engine. However, once I got the heads pulled off, I found it had a 4" bore. I took a look at the casting number(3970010) that was covered up in paint and oil and sure enough, it looks like my 305 is actually a 350. The seller was certain it was a 305 and I think that's because the heads(378450) and intake manifold were off of a 305.

But hey, a 350? I can do something with that. Lucky for me, I have parts sitting around from my 79' Malibu that have been collecting dust. With some aluminum heads, high rise intake, cam/lifters, headers, and new gaskets/pumps, this thing should be able to get out of its own way. I should be dropping it in this weekend. I'll update this thread when it's done!

Has anyone else been doing some engine work over the winter?
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Apr 25, 2009
Oh wow! Way cool! I'm going to clean up those valve covers and throw them on something else.
Personally, I was never really a fan. Just wanted to brag about my brush with greatness. I think the chrome looks good against the aluminum and black.

American Muscle 79

Thread starter
Jan 29, 2018
San Diego, CA
Did you find a reason for the engine running so crappy? Those 305 heads should have made it a a strong bottom ender.
So that's what I thought as well. With the smaller combustion chamber, it should have upped the compression. But after combing through the forums for that specific head casting, I found a lot of people saying that the flow on those heads are awful. From what I understand, in actuality, the combustion chamber isn't much smaller than a stock 350 head, and the intake and exhaust ports are too small to flow a meaningful amount of air. That combined with the fact that I'm setting aside most of the CARB compliant components should give the engine enough room to breathe.
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