327 Question: Will heads support 300 HP?

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   I got a reply from Ken Parkman [THANKS!], and now I need to turn to the "brain trust" here. Apparently I've allowed my own brain t'rust, and I need to consult people much more recently experienced than I.
I'm trying to pencil out a build on a 327 for a '57 Rebel. I'd rather get it figured out on paper before I spend the bucks on something that I may not be able to make work. The 327 in that car had 9.7:1 compression from the factory, and I'm trying to pencil out how to keep the static compression ratio and still make pump gas work. 

Obviously, I'm looking at a build using a more modern camshaft [providing I can get a core to have ground], but I'm getting hung up by dynamic compression ratio. The cams that I'd use in a Gen2/3 engine won't lower the DCR below 9.0, and the cams that move the power band higher in the rpm range to the max I think is acceptable for a "sleeper' still only take the DCR down to about 8.8:1. 

And the rule of thumb is to keep it at or under 8.5:1 to use pump gas.

I've considered using E85 for the 108 octane rating, but that also has lower BTUs; and while the car might not ping/detonate, but with lower BTUs it would also be down on power unless it's richened up a lot. I don't want to lose the torque the original Rebel 327 had. I'm looking at using 1.85/1.5 Chevy 305 valves to help a little, and I know the exhaust side flow will still be horrible. Cam specs i have in mind are around 206/216 @ .050" lift, with around .440" lift max, and around 112-114 degree LSA.

So what are my options? I'm not planning on a Vortec, because the stock compression is already around the limit for a strictly street ride and I don't need any more cylinder pressure [though once built, I might like to see if I can beat the factory Rebel 0-60 and 1/4-mile times]. 

Right now, it's all theoretical because I want to have a workable plan BEFORE I spend the bucks. And if anyone has a good contact for Gus Averill on his adapter for a 700R4, that would help. I think I can use an AMC 20 rear out of a '67-up Rebel/Ambo/Matador and weld in the factory brackets for the rear control arms so I can go to a 3.73 or 4.10 rear gear with the 700R4, using a set of Dr. Diff axles to lose the 2-piece design. The gears for the torque tube axles in those ratios seem to be made of unobtanium.

The ultimate goal is to build a '57 Rebel with a 327, a 4-speed Hydramatic [700R4 is still a Hydramatic, right?], that will match or exceed stock '57 Rebel performance. Adapting EFI might enter the picture if the budget can be found; then the Rebel I'm looking to build would be fairly close to what AMC intended the original to be.

So if you can help me out on the DCR dilemma, I might be able to see this project move off the drawing board and into the garage. I just want to have a plan that can be made to work. As in, "plan your work, and then work your plan." Thanks in advance for any helpful ideas.

Edited by Buzzman72 - May/17/2022 at 9:47pm