I don't know my 283 heads real well so I could be wrong but I thought the 327 hump heads had a chamber size the same or close to the 283 head. If so, the compression would not change.

Your engine will be easy to decipher if you can get the casting number off the back of the block behind the driver's side head.  Would you like me to post a picture of where to look for the casting?

..same here Carl. That shop manual page that Randy posted is the first time I've ever actually seen documentation stating that 327 heads were installed on some 283's. Yeah, I'd really appreciate the engine pic...thanks...my deck no. won't help me, eh??

64ragtop

Top picture has the dipstick at the start of the casting number, driver's side rear.

Bottom picture is a closeup.

That will tell it for certain. Just google the casting number (or post it here) and it should be an easy find.

1964	C	283	195HP	2 bbl	3 speed
1964	CB	283	195HP	2 bbl	3 speed	Police
1964	D	283	195HP	2 bbl	Powerglide
1964	R	327	250HP	4 bbl	manual
1964	S	327	250HP	4 bbl	Powerglide
1964	RB	327	300HP	4 bbl	manual
1964	SB	327	300HP	4 bbl	Powerglide
1964	XE	327	300HP			service engine

"POWER PACK HEADS"    


About Power Pack heads

 In the passenger cars the 265 and 283 inch engine were standard with low compression heads and a 2bbl carb.

When given the higher compression heads, 9.5 on the 283, a 4bbl and dual exhaust they were called Power Pack.

They were listed as such in the advertising also.

The Power Pack 283 was available thru '66 in passenger cars. 

 no idea were that came from, canadian pontiacs only used the numeric  idetification systems on the small blocks and inline engine im not sure about the big blocks. i posted some codes in different places, i do know that 65s use the 64 numbers and i have seen some 63 using the system and 66 also follow the same codeing . if you look in the front of your servce manual it shows some of the codes and were they can be found. when i dig up more number ill post them. the first two are the transmition the next two are year and egine type the last for is the production run. as far as power pack 283 and 327 250 hp only. no 283 ever came with double bumps in canada unless someone replaced them the chamber size would kill what little compression a 283 has 9.0 if you are lucky. dont go by printed liturature they are optomistic at best. power packs come in two flavors big and small chamber the small chamber is 59cc the big is 64 or so. the earlier one can be smaller but im not dealing with that can of worms.and as far as running on pump gas i can run up to 11.5 comfortably on 89octane so thats really not a good indicator. Casting numbers tell you what engine it is and when it was cast stamp codes tells you were it belongs and what it was optioned with. a cheat sheet .

...that's the spot and V number Carl...

Neil

...thanks. Based on what you've said I'm still confused as to these double-hump heads and whether it's a 283 or a 327. I'm going to get that number off the back of the block to confirm. It just seemed strange to me that a 327 double-humper would come with a 2 bbl and single exhaust. But like I said to Carl, who knows who did what to it over 46 years..? It might not even be the original engine (but I thini it is...).

64ragtop

From my 1958-65 Parts book:

Strato-Flash (standard V-8) 283 - "V" or "9V" preceding engine serial #
Astro-Flame  (optional V-8) 327 - "D" or "9D" preceding engine serial #

1963 & 1964 - 283 & 327 - 250 HP - heads part # 3817680
1964 - 327 - 300 HP - heads part # 3817681

For 1965 - all 283s - heads part # 3817680
For 1965 - all 327s - heads part # 3817681

as far as the part book numbers are they are part numbers not casting numbers, if you pull your valve covers you find casting numbers it will give you a casting date and the casting of the head ie what the head is the last three numbers are whats important double bumps came in all sorts of incarnations 461 462 291 etc 461 are found up to 65 starting in 62. power packs for up to 65 are 896, so check those as far as V codes letter codes never have i seen them that a chevy thing the ones i have delt with 63 66 use the numeric codes. this is not to say they didnt switch prior to 63 or after66 but i dont deal with that group so anyone haveing an original engine chime in with your numbers.

I had a fellow in Seaforth talk about a 396 that had a Canadian Pontiac suffix...

I always presumed that the engines in Canadian Pontiacs and Beaumonts and Acadians were GM    and used the same suffix numbers as GM used in their chevrolet products...
IF they used a separate set of numbers (I don't know why they would)
 then, would that, ever be a neat list to have...

Carl1 says his motor is a Acadian motor  maybe he has a non chevy GM suffix list??