Have a 416/340, Probe dish pistons, comp nostalgia cam, Sanderson headers, 915 J 1.88 (opened to 2.02) heads. It's an A/C car and I want to keep the a/c
I'm thinking of buying the Indy 'X' cast iron heads and take advantage of the smaller, efficient, heart shaped combustion chamber.. and still keep a somewhat factory looking head. But I'm concerned with smaller cc and running on pump gas. The motor currently is about 10:1
OR go aluminum heads, pump gas would be no issue.. but I don't like the "block" of aluminum head appearance- plus I've heard there can be fitment issues with the factory a/c and alum. heads.
Stock sb 915/587's I believe are about 68-70 cc; the cast Indy X are 62 cc. What kind of compression increase would I expect (1/4pt? 1/2pt?) and can you run pump 93 with 10.25:1 ? My timing is currently 34* 'all in' at about 2500 rpm.
The Indy X fit my budget.. but concerned with compression
Or should I save a little and go ProMax aluminum and get used to the look and hope the a/c compressor fits with out issue.
Thanks in advance for input/advice!

You should drive up I85 about an hour and come see the new small block sidewinders. Call me or write and I will tell you all about them.
Todd

With the continuing deterioration of pump fuel why take a chance with iron heads No way will I build a iron headed motor with more than 9.5 to1 compression ratio, even with a big cam
Go with new aluminum heads now

What vehicle and compressor style? Lots of Dakotas out there with factory EFI, AC, and Edelbrock RPM heads.

I like aluminum for lots of reasons, higher compression capability, faster cooling/no boil over after shutdown, weight savings. If building a correct restoration, then sacrifices in performance must be made. Manifolds vs headers, low dual plane intake, etc. if building a race engine, other than the FAST class, who cares if it's not factory looking?

Any issues using stock rockers on Edelbrock RPM heads?

Does the exhaust system need to be upgraded to gain some of the performance increase you are after? If you are in the 10:1 range I would think that you are real close to the ping limit on pump gas right now & in fact I think an actual 10:1 would be talking. If you know your dimentions/specs you could see what you have now & what you will after a swap. The United Machine calculator is handy (Google it). Just me I would go aluminum and I would think any AC fitment issues could be easily fabbed & taken care of. there was just a good thread on perf bennie of alum VS iron. was not real positive. Not really my area but I would think if the alum wicking away heat faster would quell the pinging from the increased CR that you would be gain performance. ??? any thoughts on any other area of your build that might be holding you back? what I would do before anything is bring your curve in faster & experiment in that area.

Aluminum all day long. Talk to Sasquatch!

Yes, aluminum heads would be beneficial, but if he holds .035/.040 quench with flat top pistons, 10:1 CR shouldn't be a problem with iron heads.

J heads mean NO SQUISH, they are open chamber heads,
unless the pistons are "quench domes" already.
Running 9.5:1 on an iron headed engine, even with quench domes, is iffy at best.

R.

A good read.

http://www.enginebasics.com/Advanced%20Engine%20Tuning/Static%20vs%20Dynamic.html

You can flirt with to 10.1 with iron heads in some cases. My brother has done it with a SB Olds 350 with iron heads that have had the heat risers filled and the valve faces and combustion chambers ceramic coated all in an effort to eliminate hot spots.

Camshaft timing, combustion chamber design, bore diameter, altitude above sea level, etc. also factor in as well. If in doubt it's better to error on the safe side.