Hi, I was wondering if anyone has used 1963 heads on the earlier Cadillac motors. I realize that 63 was a "transition" year, but I read somewhere on the HAMB that they do fit. The only differance that I was able to see was the valve covers, everthing else looks the same as an earlier set of heads. Thanks for any help, Dub. Edit: Also, does anyone know if the crank is the same as an earlier 390? (main and rod size) The only differance I have read about, is that they are lighter. Thanks again.
I know the pre-'63 390 and the one-year-only '63 390 (and the '64+ 429) have the same intake holes, and the earlier intakes can be used with spacers (the heads on the newer engine are farther apart than on the older ones). That said, I've wondered this, but have never held the two designs up side-by-side to compare. The '63 390 and the '64+ 429 are the same engine, and of a completely different design. I'm just not sure about a head swap. I know who has a definitive answer, though - ring Chris at http://www.cad500parts.com - he'll be able to tell you right off. He's also a HAMBer. ~Jason
This was posted on the Cadillac Power Forum a while back... ---------------------------------------------------------------- "i have run the 390 heads on the 331 engine. i used 390 pushrods, rockers, shafts, to make everything work. (and exhaust manifolds) there was a very big difference in preformance." and... "They bolt right up and it works well. The chamber on the 390 heads is a little different, so we generally use an after market forged piston with the valve reliefs in the right place. It will work with stock pistons if you have a small cam, but if I remember right, the compression ratio drops a little (but still makes more power). The early engines had crappy compression ratios anyway, so if you really want to make some power, you will have to get after market pistons. It isn't too hard to make it a revver and get some really good HP if you are going racing (like over 500 HP)." -------------------------------------------------------------------- Hope this helps...JW
This is what Chris emailed me back with...Ive never thought of it like this. If I can get them cheep its worth a try.--- I’ve never tried it, but they may be interchangeable. I’d check the chamber volume compared to your old heads, and see what it will do to the compression ratio. I’d also check the bore centers – I think the rocker bolt pattern is spread out a little (which means you should have to use ’63-’66 spec rockers shafts), probably because the bore centers are spread out a little more, but I have never checked that – if that’s the case, the chambers won’t line up with the bores so well.
Dub, I couldn't find Main journal size on the 331. The rod rournal size on the 49-54 is the same as the 55- 331, BUT they take diffrent rod bearings. Nominal size is 2.2488/2.2493. Clevite 49-54 rod bearing # is CB-348P. The bearing # for the 55- 331 is CB-472P, same as the 59-63 390. 59-62 390 Main size is 2.6235/2.6240. The 63 390 mains are 2.9995/3.0000. Intersting is that the 1-4 Mains on the 59-62 390 take the same bearing, and then #5 is a diffrent # of course. The 63 390 actually takes 4 diffrent part # main bearings. #1 is its own, #2 and #4 are there own, #3 is its own, and #5 is its own. All of the crank main journal diameter sizes are the same, the fiqure as given above.
Thanks for the info! I was hoping the crank was the same as the earlier 390's. Ive read that you can put them in 331's just need to turn the mains .125 and you basicly have a 390 in a 331 block. Thanks again.
I am of the belief they will bolt on. I think the 390 heads have bigger runners. As I remember 49 331 heads were center bolt valve covers, but the head bolt pattern should be the same...including 1963 heads.
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