Hey all, I am building my first 265 and currently have a 56 with 2 barrel heads. I've look at the threads and found good info on using 57 2 barrel heads instead of spending the bucks on and time on finding 56 power pack heads. Will it matter all that much if I use the 2 barrel heads I have and cut them down, use different valves and a 151 cam? Just would like to use what I can as it's all in good shape. Thanks, Wag More, Bark Less!!
I'm trying to recall if the combustion chamber volume is the same on a power pack head as a two barrel head. I think it was smaller on the power pack heads so the compression ratio would be higher. After a little research on the net it shows that volume on a power pack head was 58 cc and volume on a standard head was 64 cc. Power packs also had a slightly larger intake port for more flow.
I was just thinking with todays rather poodle piss gas, especially in California, I want to keep the compression down below 10:1. Using the bigger volume will help do that and if I change the valves a bit I was hoping to still be able to bump the cam some. The smaller intake port bugs me, maybe I should like for a set of 57 2barrel heads.
Probably depends on how you're building the engine. Will it have a stock or mild cam, what carb, what exhaust, etc. What do you expect out of it for performance? If you're building a stock engine with a 2bbl carb, then the heads you have should be fine. If you're putting a 4bbl on it and want some performance, then get the later heads with the bigger ports. Running the later 2bbl heads will give added breathing, without the added compression, and might be a wise move? But first figure out the compression ratio, with the later 4bbl heads and with the later 2bbl heads, might be that with the smaller displacement that the later 4bbl heads will give you a reasonable compression ratio. If you can't afford to buy some different heads, it probably doesn't matter.
Jim, thanks. I can afford the other heads, just trying to be frugal so I can use the funds on other things. But performance is definitely the goal, so maybe other heads are in the picture. Any thoughts on using early 305 58cc heads? Do they have bigger intake ports? They can be had cheap already rebuilt on Ebay. And the early ones would permit using era correct valve covers, although not staggered. If I was to go whole hog (maybe Santa will help), does Edelbrock make RPM heads that can bolt to a 265?
The scalloped 305 heads are junk. Almost all are cracked. The later 283-327 heads will be way better than the 265 heads. The valve cover bolt pattern is the difference if you want the 265 look. Otherwise the newer the better.
The 69-up heads with bolt holes in the end don't have the right look for an early engine...although I guess a lot of guys don't notice, or care. Sticks out like a sore thumb to me though. If you're willing to put late model heads on it, and performance is a goal, just give up and build a 350. Not that I'm opinionated or anything
If I go 350 it will be an LS2 with a t56 and be done with it. Good mileage and wonderful performance. But because I have 2 55's I was going to do my Nomad more nostalgic, which is why the thought of sticking with the 265 as it was the beginning of it all. Really good info from you guys. I going to try for the 57 2 barrel heads and build them up. Seems like a nice way to get some performance and still have the old look. I'm going with the 3-2 setup if I can find all the stuff, it looks FAST! Macho macho man! Wackiest song ever, but truth be known a little machismo goes into all hot rods. (sometimes maybe more than a little) Thanks to all for great advice and knowledge, including the old threads.
Stagger VC bolt pattern heads were used thru about half of the 59 model year, you'd probably be ok with these heads too. Some of the 58-59 heads had a bolt hole at one end, I don't know if the 2bbl heads did, but I've had two sets of power packs that did. I think the extra hole was used to mount the air suspension compressor. More irrelevant tidbits...
Yes, both '58 and '59 2 bbl and 4 bbl heads had the bosses cast on one end of the head. In '60, they went back to the smooth style heads. I had a pair of '59 power pack heads with a casting date of A 14 9, and they still had staggered valve cover bolt holes.
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