chuck perry
Active Member
Looking for stock flow numbers for the 974 heads.
Anyone have any info would be great
Anyone have any info would be great
There are a couple issues with building a 273 - piston choice and head gasket choice. Both are critical because it's a small, short stroke engine and needs all the compression it can get. If it were me I wouldn;t sweat the .060 over. You could have it sonic tested to be sure for a lot less than sleeving all 8 but IMO it's probably fine. they were cast back when making them way thick wasn't a budget issue. I'd get a set of custom pistons with a flat top and good valve reliefs and plan to runa set of Cometic custom head gakets. Then you can design a tight small chambered engine that will make some decent power on pump gas. Otherwise you're spending more to cobble something together with what I'd call old and sub-standard parts. Use the 302 heads - upgrade the valves to 1.88/160, do a little basic clean up, and reduce the chamber to give you a true 10:1 with a tight (.030) quench distance. he .528 is a decent cam but much better can be had. I'd look for a modern solid profile with 225° or so @ .050" and lift around .500. Run a 318/360 Performer (easy to get at swaps - nobody likes them on 340/360s) and port match that to the heads. That Torker's not worth any time on this combo. I'd also recommend a new Thunder AVS 650 or Holley 570 Avenger. That would be my starting point. Even witht he gearing the trick is torque for a 273. It will rev just fine - but you need it to get the car moving and accelerate it. Not just make high rpm horsepower.
I have several 273 blocks of lesser bore if needed and if date matters what month and year are you looking for or around?
From what I'm reading, when it gets right down to it the 273 performers
The "best"running the basics............. 3 C's
Cam carb and compression
As long as I got the 4bbl pistons a a small chamber head(with a littlie work done)
And a mech cam under .530 all shound good?
Nope. The 4bbl pistons will not generate the static compression especially given any available head gasket nor is it tall enough or of the right configuration to generate an effective quench.
While I agree with some of what Dave notes in terms of head theory - most of it IMO is overly concerned with relatively small details that don't add up to more power. You will get more power from the larger valve, especially given the rpm range you're contemplating. If you're really concerned about the shrouding then you can notch the bore but I'd rather not bother. Just my opinon of course.