Now before you go tell me it would be better to put a bullet in my head than still use LO3 heads....please just answer the question. Standard LO3 heads, with a 3 angle valve job and ported and polished......what kind of HP gains could one expect?

Please keep the mean remarks to a minimum....I'm just looking for answers here.

Has anyone ever used these heads after they've been worked up?...or are we all just saying they suck, because that's what we've been told, or because we've actually used a set?

 

stock LO3 heads are not as terrible as most people seem to think. no, they are not any where near the best castings gm ever used, but they are far from teh worst too.
with a mild p&p and valve job i have heard gains from 10-40hp. it really depends on how good the port work and blend is and how well optimized the rest of the combo is.
if you do a mild cam and get a custom chip at teh same time you can certainly see gains of 6-7mph of trap speed. (hell, the cam with no chip or other mods is worth almost 4mph).
a valve job is usually around $100 and i have seen mild port aith a complete clean up range from 150 to 250. you coudl shave the heads a little too while they are off to try to grab a touch more compression.

later
tim

 

What about using 350 heads with 1.94/1.50 valves with 64cc chambers? Could that work, as long as the EGR crap is there and they're centerbolts?

What exactly happens by going from 58cc to 64cc chambers anyways? Poorer gas milage I'm sure, but by how much? More ponies, but by how much?

By the way, the cam would be an LT1 cam.....how much lift do the springs need to be able to take to work with it?

-The Gunny

 

mileag edoes not really change with compression changes. you will lose a bit of power from teh lower compression, but you coudl get away with more timing too, so it is kind of a wash.
if you are gonna use 350 heads look for tpi heads, they are a bit better casting to start with if you are trying to stick to s stock or cheap set of heads. they are also small chamber heads, so you will not have to worry about a compression drop.

later
tim

 

What's the casting number for the 305 TPI heads? And at what rating do the springs need to be at in order to take the LT1 lift?....what are the specs of the LT1 cam anyways?

-The Gunny

 

The most important thing to get out of the 187 heads is the retarded swirl port block they put right on the short side radius on the intake side. Like Ive said a few times before, my friend has some self ported 187s with an lt1 cam and a 670 holley on his car, I think he's going to the track on the 18th so we'll see what the setup is capable of (keeping in mind its still stock chip and a posi 2.73 rear).

 

305 TPI castings are 083. I've played around with the 187 heads. Minimal gains are had from working with these heads. The intake ports are already a larger size which decreases velocity already and when you port them, you just lose more velocity. A 3 angle valve job doesn't do a whole lot because the amount of air/fuel that can pass the shrouding inside the runners is what matters; if the air/fuel is restricted getting into the intake valve, then whats the point in opening them up?