im building a 406 and i need it to run on 93 octane for weekends on the streets. but i think im pushing the limits....

Kieth Black flatops -7cc 4VR KB125
the SIR Eagle lightweights 5.7 SIR5700BPLW
AFR aluminum 210cc w/ 76cc combustion chambers pn#1050

i know i need the cam to really figure this out but i havn't researched it yet so suggestions would be nice. the pistons advertise 10.1 with 76cc
my questions are

does CR lower or rise with aluminum heads?
and if i have the block zero decked with that lower or raise CR.

im new at this and im teaching myself(with help of you) how to go about buying and putting this engine together. any suggestions would be great especiallly for the cam since i want to start buying my parts, atleast the rods and pistons, but i didn't wan to buy them and find out im through the roof on compression.

 

The real CR with a more-or-less stock deck (.025") is closer to 9.6. Zero-decking the block raises the CR from there. At .000" deck height, you'll get almost 10.1:1.

As long as you use a cam that's appropriate for the rest of the motor, in particular the head flow, and not something stupid like some "RV" cam, even 10.1:1 will be fine.

The material that a head is cast out of has no effect on the CR it delivers. Only the chamber size affects that.

 

thank you. i'll have some stupid questions from time to time on here, but it's only cause im trying to learn and i dont have any1 to teach me.
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i havn't really studied the whole aspect of cams(being what is appropriate for different builds and goals) so i'll probably have some stupid questions on that subject here shortly. if anyone can suggest a nice one go ahead

 

Also, aren't aluminum heads more forgiving of higher compression ratios? Like they're less prone to detonation or some such?

With 93 octane gas, you should be OK at 10:1 with those alum heads. Maybe use a thick head gasket?

 

You can ask question on here all you want about cams and you'll get as many different responses as you will posters. The only way to truely maximize your combo is to call the cam manufacturers and see what they recommend. We can all offer suggestions, but you need to talk to the top guys/head people since this is what they do all day everyday.

My personal recommendation is Bullet Cams, dont know what they do with the grinder but they make more power than the same speced out Comp or other popular brand. Prices are the same as any other manufacturer, but you have to have all the cars info, intended use ready sine they'lldrill you on questions before they make a recommendation...as it should be. They've got thousands of grinds/profiles to choose from other than the standard Summit/Jegs listed junk that gets installed to death by members on this board. I sent in for a Lunati cam catalog years back and got a 56 page #4 font size for listing of all the different cams they have-thousands of grinds that most of us have never seen/heard of.

Yes you can get away with slightly higher compression with aluminum heads, generally .6-1.0 due to heat disappaction. But again, everything needs to be looked at as a package when deciding on a cam. I was at 11.3:1 actual compression and ran on 92 octane for example.