V6 305 Head Compatibility (Between Models)

[TRybas]

Gentlemen (and Ladies),

Can anyone confirm the compatibility between heads and blocks throughout the years (models) on the V6 305’s. I have a 1960 305A with a cracked head and leads on heads from different models (305D, 305E, ect). I thought I saw it on here years ago that they are interchangeable but I’m coming up blank on my search.

Side note: If anyone on the east coast ever comes across a 305A please reach out.

Thanks in advance,
Tim R.

[Funky61]

Found this question and response in the Archives previous posts section;



I'm not sure now, but are all the V6 engine "blocks" from 305A,D,C,D,E, 351C,E,M, 401C,M the same physical size. So oil pans and all head combinations will bolt-on without any problems?
Frank Van Delden Maryland


Yes, All 305A,B,C,D,E, 351C,E,M, 379, 401, 401M, 432, 478, 478M V6 engines, other than bore sizes all share the same basic block architecture and dimensions therefore cylinder heads, corresponding intake and exhaust manifolds, valve covers, pushrod covers, distributors, water pump-timing cover housings along with corresponding water manifolds, camshafts, gear drives on 401 to 478, chain drives from 305 to 379, crankshafts other than 73 to 74 478M, oil pans, oil filter housings are INTERCHANGEABLE !
Pete Chronis

[TRybas]

Funky61. Thank you.

[geasson]

I recently sold a 1960 B-Model truck with a complete 305 A in it. The buyer was intending to put the B-Model cab on a rat rod and was not planning to use the 305A. It is in southwest Missouri and if you want I can get his contact information.

[baccaratplayer]

Thank you Funky61.

I've been looking and wondering this same question.
I've got a 66 1500 with a 351E engine. It has been running terribly since I got it in December. My go to mechanic say that either the distributor is bad, or the
carburetor is. After looking at things, I have decided that the issue is the distributor.

The first thing I found was that the points system had been converted to a Pertronics Ignitor II. My first thought was that it had gone bad. I replaced it with a new Ignitor II, but the issue persists. It runs great at idle and up to about 2,000 rpm. I retimed it because the PO had the timing at something around 15 degrees. All that did was to get things down to a reasonable condition. I looked at the distributor again and found that the mechanical weights are not working correctly. I started to look for a rebuild kit for the distributor, as a 351E, and cannot find anything, anywhere. I thought perhaps that "what if a 305 distributor rebuild kit or complete distributor would work".

Your post here solves my problem if I can find a 305 distributor, or rebuild kit.

Thanks a lot for the information.

Mike

[Funky61]

Baccarat, I may have a distributor. I’ll PM you if I find it.

[baccaratplayer]

Funky

I'd appreciate it.
Seems like some things are almost impossible to find for the 60-66 GMC.

Mike

[baccaratplayer]

Funky61

I PM'd you. I cannot tell wether it went through or not.
Let me know.

Mike

[Funky61]

Hi Mike, I did not receive it

[James]

All 305A,B,C,D,E, 351C,E,M, 379, 401, 401M, 432, 478, 478M V6 engines, other than bore sizes all share the same basic block architecture and dimensions therefore cylinder heads, corresponding intake and exhaust manifolds, valve covers, pushrod covers, distributors, water pump-timing cover housings along with corresponding water manifolds, camshafts, gear drives on 401 to 478, chain drives from 305 to 379, crankshafts other than 73 to 74 478M, oil pans, oil filter housings are INTERCHANGEABLE !
Pete Chronis

The only thing that I know that is not interchangeable is mixing the magnum head, intake or exhaust manifolds with the smaller (305) heads. The ports on the magnum is a lot larger and will not seal if mixed. I think there is a different in the oil pump mounting bolt too (5/16" vs 3/8").

Use the magnum heads with magnum manifolds and smaller heads with the smaller manifolds.