[cas]

I have a what i believe is a stock 1976 350 2v motor with a 4v intake and carb on my 68 lemans, super drivable, low octane gas, average pepiness, but easy driver.

Would there be any real performance upgrade by installing a set of 66 heads off a 71 455? I've had the heads on the shelf for a couple years and was wondering if its worth the trouble to have them cleaned up and put them on lemans or would i be waisting my time.


Thanks guys for any i put

Chris

[b-man]

The #66 heads from a 455 would be pretty much the worst match for a 350 engine you could find.

The huge 114cc combustion chambers would plummet the compression ratio down to 6:1 at best, it wouldn't run anything close to peppy.

The #66 455 heads are really only good for either a low-octane 455 or a boosted (supercharged or turbocharged) 455.

Your 1976 350 currently has 7.6:1 compression at best. A good inexpensive head swap would be a set of '68 - '70 350 heads, casting numbers 17, 47 or 11. Any of these heads would bring up the compression enough (8.5 to 9:1 range depending on which head casting) to add some pep and still allow you to use 91 octane premium fuel.

Just for the record, the ports on the 350 and 455 heads in question are all essentially the same. What you're looking for here is a reasonable compression bump for increased horsepower and torque at every RPM.

[ponyakr]

If you don't wanna swap heads, this is a good app for one of the small Voodoo cams. They will increase cylinder pressure in low compression engines. The 256 may be a good one for your 350.

https://www.lunatipower.com/Product....d=1774&gid=287

You can also buy thinner Cometic head gaskets, which will increase your compression slightly. These 2 changes will give you a little more pep, without changing heads or having the heads milled down.

http://www.jegs.com/i/Cometic-Gasket...ductId=1288713

Those late model 350 pistons did not have any valve reliefs. The earlier ones did. So, if you put the early heads on 'em, how much cam lift can you get by with, without valve reliefs ? Don't remember anybody addressing that.