gun4hire

Well, your questions are a little generalized.

Casting numbers can usually be found under the rockers, IIRC. Once you have them swing over to mortec.com and do a search for them. That should tell you the size/type head you are dealing with.

I've never had heads milled, so no idea what it cost. Should be able to call a machine/engine shop locally to you for an estimate.

10.72 C/R is a bit higher than I've ever been recommended for use with iron heads. You can run into detonation problems. I believe the iron head LT1 in the Impala SS runs a 10.5 C/R, but those engines feature reverse flow cooling (heads first) to reduce the chance of detonation.

Power increase is entirely dependent on what you have right now. If you already have 64cc heads and are running something like 9.5 C/R then going to a little over 10 may not make a HUGE difference. Once you know what you are presently working with, you can get better recommendations.

WhiteLightnin83

well sorry about the questions being so generalized, i'm just trying to get some basic knowledge of what i'm doing before i start wasting money. i'm sure it makes sense that i need to know what i'm working with before i start trying to modify it. i realize that the 10.72 ratio is a bit high for the iron heads, but the next step below that is like 9.8 and i figure with the 10.72 rating i wouldn't actually get that out of them. i'd expect more around 10.5 at the most. my c/r is only like 8-8.5:1 so i figured the increase would be more substantial and actually do something, i realize that from 9.5 to 10.5 wouldn't do a whole lot becuase its not a very substantial increase, but i'm at about 120 psi per cylinder last i checked and 120/14.7 is about 8.2:1 so my compression is pretty stock. any suggestions on a good set of heads for under $1000? also, what happens when i encounter detonation, and i mean what exactly happens and how damaging is it?

DarthIROC

Honestly 9.5 isnt bad for a motor ran on pump gas. Most crate motors you can buy for street use. Some of which are pretty mean, are running 9.5:1 so its not a bad ratio to run.

If you buy a set of decent flowing heads, and I recomend you dump you puny stock cam while your already doing all this work you should run fairly strong.

WhiteLightnin83

i know 9.5 isn't a bad ratio to run, but i would like to go higher becuase in the near future i plan on putting some nice vortech heads on the motor and maybe a bigger carb than the 650 holley thats on it now. believe me, the cam was the first thing to go out of the motor, those stock cams are about as worthless as a dick on a gay guy. the only thing i remember about the cam i put in it last summer was something like .504 lift or something, i know it was the largest i could buy and still be a hydraulic, rather than a solid.

DarthIROC

Wow bro I dont even really know where to start on that one. First off, buying a cam jsut becayse its the biggest one you can find is a horrible idea. And if you could find the specs on it that would be helpful. Luckily .504 lift isnt that much so it sounds like in your blind stubling about you actually didnt do yourself too badly.

But again like I said, you want to get your compression up with your heads. So if you plan on doing heads int eh near future, just replace the pistons you have in there with some nice flat tops, it will still run fine, and just deal with subpar compression until you buy heads with ideal combustion chambers. And if you run much more than 10.5:1 on pump gas and iron heads you may detonate.

HeavyChevySS

I wanted to chime in with my 2 cents..

Cheap aftermarket head that makes great power compared to it's cost is the DART IRON EAGLES. Check Summit for prices or Ebay or racing junk.com or etc...
Vortec heads make good power too but you have to change the intake as well.

The key to making decent power is really in the heads. You want to make sure all your engine components are matched as stated in a previous reply.

Heavy

gun4hire

Here's a pic of what detonation can do to your pistons...

PIC

Do yourself a favor - unless this will be a track-only car...stay under 10.5...preferably under 10.0 if using iron heads. The slight extra compression will not yield a ton of HP, and the risk of detonation isn't worth it.