Comp 306S cam

[ToddK]

Hey Jay, I saw on another thread you mentioned you used a Comp 306S cam in your 390 stroker. What compression was that engine, and what was the idle like? Did you run it on pump gas? What rpm did the HP peak at?

Reason I'm asking is I have bought a cross-bolted 406 short motor, using a 4.25" stroke crank, 462 cubes. It has domed JE pistons to give 12 to 1 comp with 76cc chamber heads, but I plan to mill the domes off the pistons to make them flat tops. This should give me around 11.2 to 1 comp with 76cc chambers. The cam in it is a bit big for what I plan - to use in my 63 Galaxie. It's 266/276 @ 0.050". I'm thinking of using either a Comp 294S or 306S. With the 294S, I calculate the dynamic compression to be around 8.2, I think I should be able to get away with running that on 95 octane gas. But if I run the 306S, it should bring the d.c. down a bit more.

As much as I'd like to run the bigger cam, I think the 294S should be good for my application. Any thoughts?

[jmlay]

http://www.carcraft.com/techarticles/ccrp_0808_ford_390_fe/viewall.html

[jayb]

The Car Craft link above has most of the details on that engine.  Static compression was 11.1:1, and the DCR for that engine calculated out to be 7.8:1.  It ran fine on pump gas, although for most of the dyno work I did for my book it got 110 octane race gas to be consistent with the other engines.  Idle was a little rough, but not bad, running in the 900-1000 RPM range.  Horsepower peaked at 5900 RPM with a Performer RPM intake.

The bigger cubes of your engine will help the idle, and bigger cubes will always help tame a big camshaft.  What does the DCR of the 306S work out to with your combination?  I think you could go with either the 294S or the 306S.  If you have cast iron heads, you may be pushing the DCR limit a little with the 294S; my rule of thumb is to limit it to 8.25:1 with cast iron heads, and 8.5:1 with aluminum heads.  If you are planning to use aluminum heads, I think the 294S would be fine.  You could also mill a little bit less off the pistons to keep your static CR up, and go with the 306S.

Decisions, decisions...

[bartlett]

I have the 294s In mine and so far I like it, It ides pretty nice and has good power. It likes to scream, just as a test I let it zing up in second gear and it pulled to 7grand without valve float and the power was still there. My wallet made me shift  ....Now my msd rev limit is set to 6,000  no reason to run it to hard in a street car.

only things I have considered about changing are , less stall (motor has plenty of power down low) motor mount choice ..( running soild poly and it vibrates to much)