disecting a cadillac motor... what do I have here?

Gregg, the stock bore is 3.8125" so yours would be 0.15 over. You can bore these blocks to 4.000 and use stock 56 Cad pistons for 365" This will also rase the compression with bigger bore. I'd bore it to 4 " for the additional torque you get. Also did you know that the stock pistons did not come up even with top of block the engine designer made allowances for rod stretch at higher rpm's. Later Hank.

 

Normal oversizes are .010" ('ten over'), .020" ('twenty over'), etc, not .100" ('one hundred over'), .200" ('two hundred over'), etc.
4" bore is probably pushing it, but it's been done.

 

The waxy substance you describe on the parts in the engine is exactly that - the paraffins left behind from old non-detergent engine oils. Pefectly normal.

That is a really neat find! Enjoyed reading about all the discoveries.

 

He is already bored out pretty far then, as he measured 3.962". Creeping up on that 4" bore, but smaller than the 365, and outside the normal range of 331 oversize pistons. So assuming that his measurement is dead on, there may be an odd piston combo in there?

 

OK, I was wrong.

I was reading the dial bore gauge backwards

the correct reading is 3.937 at the base of the cylinder. throughout the wear area the max I have found is 3.938. any ideas what pistons these may be?

any way to identify the crank?

also are 365 pistons the same pin height, etc? can they be used with the 331 crank and rods?

 

Still sounds outside the range of any oversized 331, and smaller than 365. I think that you have a 3 15/16" piston like out of a 330 olds or something bored in there, but I'm sure other's opinions may differ.

 

These may be original, but not to a Cadillac!

 

So did you throw the disassembled hulk under the work bench, or what gives?

 

There is a detailed Cadillac 390 buildup with lots of good info. in the May 08 issue of Hot Rod Deluxe.

 

things have been difficult at work, we had guests in town for a week, and basically life has gotten in the way. I am working on setting aside the money for parts and machine work, and I will be back at it soon.

 

Hello,
Did anyone id this engine? I continue to find and hear there was no factory adjustable valve train for these engines...just curious what the word on the street is. Any casting numbers on the block and heads?

 

I think that he had a stock 331 motor bored out w/ 330 Olds pisons (my opinion), and super cool aftermarket McGurk rocker arms, and homemade solids. OH, and ground cam. engine painted white once. I think thats all I got. I watch this thread regularly, would give a bottle of Mezcal for more info...

 

I don't know how helpful this is, but I just went and took a few snaps of my 1953 Oldsmobile Rocket 303. It's totally stock. I know the Cad & Olds motors were the same somewhere around these years.

 

I can not seem to find this issue of HRD. Anybody have a copy they would be willing to scan (390 build-up section), or possibly to sell? Odd that Primedia doesn't offer it in it's back issues.

 

I have been trying to find one for months, no luck, several have said the would scan and print but no luck. The back issues sold out almost instantly I have been told. Oh Well!!!

 

I know the Cad & Olds motors were the same somewhere around these years.

Never the same.

 

well, I am going to the Charlotte Autofair this weekend. Maybe I can locate one (and scan the article).

Charles

 

Never the same perse, but look at his pison/bore measurements at 3.937" : too big for any 331 overbore, too small for 4" 365 or 390 bore, so that leaves us with 3 15/16 pistons... what other pistons but Olds 330 fits that hole?

 

I have these 331 Cadillac "Dimpled" valve covers, were rusty chrome, but I had them powdercoated and added aftermarket decals. These valve covers appear to be stock or 1950's aftermarkets, heavy steel.