Compression and Cams

[GEARS]

Hello all,

Im my 86 S10 I currently am running a crate 3.4 longblock, with heavily ported irons, ported TBI intake, Holley 400 tbi, Comp 981 springs and matching hardware, and a Crower 03043 cam.

The compression in this motor is a tad over 9:1, and them cam specs are 212*/218* 464"/479" with 1.6:1 rockers. Runs great, but I want to drop my 3.42 rear end for a 4.11. And with the higher gearing, I thought why not try a bigger cam too?

I am looking at the crower 03050. It has a 226*/234* 501"/524" with 1.6:1 rockers. My rpm range through the 5 speed will be perfect with 4.11's, but should I bump the compression up at all?? Would this be necessary to run this cam??

Thanks.

[SappySE107]

Wont be necessary but I would bump it up if you can.

[trotterlg]

The more overlap the cam has the more the effective compression ratio is reduced. With iron heads you will not be getting a complete fill on the cylinders at high RPM, so I think you should bump up the compression as much as you can. You really need better flowing heads, but a cam with a small LSA may be able to compensate a little for you. Larry

[GEARS]

The more overlap the cam has the more the effective compression ratio is reduced. With iron heads you will not be getting a complete fill on the cylinders at high RPM, so I think you should bump up the compression as much as you can. You really need better flowing heads, but a cam with a small LSA may be able to compensate a little for you. Larry

Ya I plan on 9.4:1 with a 0.027" gasket, and also advancing the cam another 4* on the timing sprocket. I played with the dynamic compression calculator, and with this setup I can actually raise the dynamic compression a tad from what it is now with the smaller wide lsa cam