robert_farmelo

Hi All,

I'm putting together budget 440 and have some KB-237 pistons which yield around 9.8:1 with my 906 heads. I want to be able to drive this with 87 to 90 octane gas mostly and no more than 91 for hard passes and would like to know if anyone has experience with this setup, specifically what cams can achieve my goals?

I've done the dynamic compression ratio calculations on a few cams but from what I understand that DCR is not an absolute predictor of detonation tolerance so am looking for real world experience...

My setup is very basic... Block and heads are not shaved. I will not be getting any appreciable quench from this setup. I do not want to have to back off ignition timing for the sake of eliminating detonation.

I also don't want to have to machine my heads for high lift so am probably limited to around 0.45" max lift or so.

My only variables are cam specs and head gasket thickness...

Oh and another constraint is I need to have enough manifold vacuum for power brakes...

The car is a '73 B'cuda with 727...

Any suggestions?

Thanks,
Rob Farmelo

67 GTX

you might need to used 93 octane with that
i have a little higher compression than you, so you might be able to get away with 91

robert_farmelo

Thanks... I'm thinking my goals may be unrealistic...

67 GTX

you may not have enough vacuum with a high lift cam
but, you can install an external vacuum pump
then it'll work

theomahamoparguy

It is going to be hard to run 87 octane with over 9.5;1 comp. especially with a big block. I guess you could run something with wide LSA like maybe the old purple shaft
(284-484 on 114 LSA) If you put it in retarded position a bit (2-3 degrees) maybe it would bleed off enough pressure to run 89. Actually your best bet might be a set of aluminum heads. The only other thing I can think of would be to call a cam manufacturer's help line. (like comp cams)

robert_farmelo

Thanks for the input guys... I'll give comp cams and maybe the mopar tech line a call.

67 GTX

good luck
let us know how it turns out