I had a closed chamber iron head Cleveland with TRW popup pistons,compression ratio of around 11.8:1 in my 68 GT 350 for ten years or so.
I tried several cams, headers and
induction set ups.
It could never produce the power like the,current engine in my Pantera does. The chassis just created breathing issues that could not be overcome.
It needed bigger tube headers, the Webers were too close to the hood, etc.
It is also noticeably heavier then the original 302 was.
My final decision was that it wasn't worth it in a Mustang chassis.
I will say that I never blew it up either even at .030 over, although it seemed at times I was trying to really hard?
In that car I went back to the original 302 block, 4v Windsor heads, race ported with 1.94/1.60 valves. 1-3/4 tube headers, 236 @ .050 solid lifter camshaft and a 10.3:1 compression with a 347 kit and a 2x4 Holley induction.
That run in front of a Doug Nash 4+1 speed, now called a Richmond 5 speed. The 3.26 first gear does help.
It works much better then the Cleveland ever did and is about 100 pounds lighter BUT as a matter of fact, it needs more cam.
This one isn't enough. It needs to go to 1.7 ratio rocker arms for more lift.
The Cleveland however seems like it was made for a Pantera? Everything that makes it a killer engine fits in the car. 180 degree headers with 2" primaries, Ford A3 high port heads, Weber 48 ida carbs with 5" stacks.
I do have a lot of cam in it though. A Compcams solid lifter 294s.
George could give me permanent KP as a result but the way that I use the car it seems perfect?
It screams like an F1 car right off of idle.
I learned my lesson with compression ratio. My Pantera engine is a 9.5 engine.
Don't believe this business of blowing compression out of the exhaust with cam timing. Simply put, it doesn't work.
Not unless you go to RADICALLY MORE overlap where you actually hear the exhausts spitting at idle. Where that is, I'm not sure exactly but probably with a race type only cam with overlap in the mid '80s?
No matter what you do it is still the static compression ratio that determines octane since it is what determines the internal cylinder pressures.
Octane is a measure of the compressability of fuel. The higher it is, the more difficult it is to make it explode by compressing it.
As an example, diesel fuel has a much lower octane rating making it much easier to explode it by compression, which is essentially how a diesel engine runs.
I will also point out that the same camshaft in different cars, seems different.
The same cam that is in a Pantera will seem calmer in a Mustang or more radical in a Pantera.
Ford was on the right track when they produced the CJ cam for the Cleveland. The problem was that they retarded the timing in the cam itself for production and it needs more lift, a lot more to make the heads work.
George's idea of making the CJ better, or maybe correcting those oversights is actually a very good idea.
The stock sound of that CJ cam through the Pantera's Ansa mufflers actually sounds quite nice and muscular. It is not out of character to the car at all.
IF you go that route, contact the cam manufacturer and ask if the timing in their "replica" CJ cam is retarded as well.
Other than that have a great time traveling to check out how all the different cams sound?