i dunno about the block. it may, but its still in the car haha. why?

i may have to bite the bullet and get some made. i could call probe up

 

KB Performance used to:
http://kb-silvolite.com/index2.php

This should help:
http://www.themustangshop.com/clevor.cfm

 

Did anybody notice that those pistons have a 20 cc DISH? That'll kill any sort of 289/302 compression ratio pretty much no matter how much you mill the heads and deck the block.


Norm

 

That was 4V heads assuming about 10:1 compression and a roll cam. I just reran the numbers with Aussie 2V heads and a flat cam with duration @ .05 of 236. The numbers are peaking at 350hp@6000 rpm and 360ft*lbs@4000. This is with a dual plane. You can get more from a single plane if you want to sacrifice your lower end torque. You are still going to need to spin this to 7500 or so and will not may any torque below 2200 rpm, so you will want a torque converter with a higher stall.

The main girdle will keep the main journal caps from wobbling while this thing is spinning fast. The stud girdles will keep the valve studs from wobbling under high rpm rocker movement and the valve brace helps keep the black from splitting in two. All three help prolong the life of a motor spinning high rpms.

 

^ well, 350 ponies from a 302 isnt too shabby using 40 year old heads eh

 

I did not notice that, but they are not going to work anyway being that far in the hole. He would have a 5.0:1 compression ratio with those pistons. Not going to work well! I think he should shoot for somewhere in the 9s or low 10s in compression ratio.

I just ran the piston to deck clearance on his setup and came out with a .279 piston to deck clearance, which is going to make really low compression ratio.

Racin66, because of the size of those combustion chambers (63cc), I think you need to shoot for 0 PDC and maybe a flat top piston. That would put you at 9.6:1 compression ratio. I cannot speak for valve to piston clearance on that setup, but that will get you where you need to be on the CR.

 

When I built my 383 stroker, I had custom pistons made from Ross. They were not a bad price and had exactly the PCH, dish, and ring setup I needed for my application. Do not try too hard to make stock or catalog pistons work. That is sacrifice you do not have to make when it only costs $850 to have custom forged pistons made.

 

I think that assumes compressed head gasket thickness of 0.035" or so. Zero/minimal PDC, steel shim head gaskets, and high revs might not agree with the things that move inside.


Norm

 

FWIW the circle track motors we used to build had pistons that actually stuck out of the hole, and spinning to 7k or so around the track we never had a failure. now, you could actually read the piston part number in the carbon layer on the deck surface of the heads LOL, but they never grenaded

 

Norm, I am not sure how else to get compression above 8:1 without going that route. The only other option is to run a smaller combustion chamber, which would necessitate aftermarket heads, which he does not want to do. I ran my numbers against a .039 compressed head gasket. You can go with a .041 std head gasket also. Neither make much difference in over all compression or valve to piston clearance. Running a zero PDH should not be a problem, but he may need valve reliefs. I do not know specifics on that for a 302 or 289. If he does, he may need a pop up piston with valve reliefs to get a decent CR.

This has gotten my research mode cranked up. The be an accurate Boss clone, it would need 10.5:1 CR with a 1.529 PCH, 0.013 PDH in '69 and 0.033 in '70, 63cc heads in '69 and 58cc heads in 70, and 5.150 rods. The valves were also different in '69 than in '70. Not sure about the piston valve reliefs or piston dome though.