I know that with the 60cc chambers on teh edelbrocks you will lose a tad bit of compression. Can that be made up with a thinner head gasket. Can the SR torquers be ported to match the flow of the Edelbrocks. Which one (when bolted one) would make more power? I see mustangs that use 64cc heads for the 5.0 and wonder why can't lo3 guys use the 60cc. I want the lightweight of the aluminum but HP is my greatest desire.

 

The 2cc won't make that much difference but the 2.02/1.60 valves of the edelbrock will cause problems with the cylinder walls in your 305.

 

What kind of problems will they cause? They clear the cylinder walls. NJspeeder has been running them for awhile. He's having no problems with them. Do you know someone who has had problems with them?

 

Edelbrock states that you can maintain compression ratio on a 305 with these heads by using a smaller gasket.

I would think aluminum heads would always be better than iron cast ones.

 

this is a very common misconception. they will not hit anything and will require no notching or anything else, you just have to be slightly more conservative on your cam choices.
this is a good place to mention the great thermal efficiency debates iron heads are more thermally efficient and therefore transfer more heat energy to the piston, therfore transfering more power. aluminum heads are not as efficient in this way, so instead of transfering some of the energy they absorb it and disperse it into teh cooling system, but, since they are less efficient you can get away with a littel more timing.
this is the simplified version of the debate because i do not fully understand hwo dramatic teh differences are or can be. but i get the feeling both can produce similar power and the aluminum will knock 50lbs off your car.

later
tim

 

Since the aluminum dissapates the heat better insted of containing it the way iron does, you can run more compression with the aluminum Heads. The extra heat that you'd have with the cast iron would predetonate causing baaad stuff whereas that won't happen as easily with the aluminum heads. The LT1 and LT4 take this a step further because the heads are cooled first by the reverse flow cooling method. So those can handle even more compression. Ligenfelter sells 12.0:1 compression Lt1/Lt4 heads that can run on pump gas. You'd be in a major pickle trying that with iron heads on a gen 1 block without jumping through some hoops to make it possible.

 

Tim, you beat me to it.
If you had 2 heads identical except one is iron, other is aluminum, the iron will product more power with the same compression ratio. The aluminum heads DO however, knock off 50lbs of the front end and you can (should) run higher compression to make up for the thermal efficiency of the chambers. It's funny how the LS1's have aluminum heads, make near 350hp at crank and get over 30 mpg on the highway! Of course that's with the 18^ heads and one totally differenct setup.
A good example might be the comparison between the Impala SS fron 94-96 with the iron head version of the Lt1. Those cars FLY!
Iron is also more forgiving with spark plug threads, head gaskets, and over all reliability. Although I wonder if they're more or less acceptable to cracking I would imagine so but not sure about that.
Anyways, go with iron for bang for buck, aluminum heads are just too darn expensive for a daily driver. Even Tim has his Cav to drive when his car is on jack stands!
Look at the Dart Iron Eagle heads. They make mad power and are very reasonably priced, a lot more bang from those heads than similar aluminum heads.
Tim, have you done any calculations that would tell you how close the valves are in the cylinder? I'd like to draft out an image in CAD that would show the exact location of the valves at max lift but I can't find any information regarding the edelbrock valve heights, centerlines and that crap.
If anybody has links to some small block chevy dimensions and head dimensions, please post em or e-mail me.

 

aluminm would warp before it cracked. There was a chick at school that warped her entire all aluminum inline 6. Lucky for her, her uncle is a BMW master mechanic.

 

You guys that are trying to choose between aluminum and iron should really look at some flow numbers of the heads for a good comparison. If you look at the Vortecs, they outflow almost EVERY iron AND aluminum head manufactured until you get up into the $1100+ price range (canfields, AFR's, etc.). Below .500 lift on the intake side, they outflow the Edelbrocks, Trick Flows, GM Phase II "Slow-Tie" heads. Really, guys, Vortecs are the way to go. On the exhaust side, they leave a little to be desired, but still are comparable to heads which cost more than twice as much. As soon as I get a few hundred bucks, I'm going to swap on a pair myself. For a comprehensive flow test of lots and lots of heads go to Chevy Hi performance's home page. In fact, I'll post a link here in a sec.

 

How do you mod the EGR to work with the Vortecs and Vortec tbi intake?
SC

 

you have to tap into the exhaust and then tap into the the intake below the tb somewhere. there si a company that sells a kit to do it.

later
tim

 

I saw a flow chart, and the Edelbrock performer kicked the vortecs but bad at any lift. This was not a performer center bolt head though. It doesn't flow as good with 60cc chambers. The performer center bolt heads flowed just slightly better then the vortecs.

 

I would always choose iron for a street car. There's something about mating iron to aluminum that doesn't sit well with me. Also, threading a steel spark plug into an aluminum head makes me cringe. Again, you do loose a ton of wieght, but in a street car I don't see how that makes much of a difference since most will put 400 lbs of stereo equipment in the back

I would look around at the manufacturers websites. I know World Products lists the flow ratings for all their heads.

 

my subs/box/amp dont weigh 400 lbs and are easily removable for track use

 

Uhh... no they don't, at least not according to this article:

javascriptpenWindow('http://www.chevyhiperformance.com/editorial/article_popup.jsp?id=41599&sidebar=1', 600, 400,'Sidebar')


Sure, the exhaust numbers are better, but the intake isn't.

 

Hot Rod picked up 17 hp with the vortec heads (milled .040) and the Edelbrock Vortec manifold over the Torquers and their standard style manifold.

Question: is the bolt pattern the only difference in the vortecs? Are they the same size physically? I thought I read they were taller or something?

 

the intake ports are higher. Very tall and narrow. Mopar style.

 

...But do they outflow the ProAction Iron Lightning heads (at $249.00 each)?

 

Hmm... interesting. Would there be any way to mate the Vortecs with a standard intake manifold, or would the ports on the manifold be too wide and not tall enough?

 

No, you must mate the Vortecs to a vortec style manifold. That is the only thing that really sucks about going Vortec-- expensive intakes. Once you go Vortec, there really is no going back! This makes me think about bang for buck in that it may not be that great of a deal (Vortec) if you have to spend 200 bucks or more on an intake while standard SBC intakes are dirt cheap new and used.

 

people have tried and some have had the vortec ports peakign out from on top of the intake.

 

Hm... poo. Luckily it seems that you can get pretty good money for vortecs, even used, so if you decide to go back to standard heads you can get most of your money back.

 

Here is the site I got my information at.
http://www.sallee-chevrolet.com/Fast...der_Heads.html

This site sells both types of heads.

The vortecs flowed better at .500 lift but since there only good for about .470 unmodified thats beside the point. I don't know where this site got these numbers, I only said that I saw a chart showing edelbrocks kicking vortec butt.

 

Man those fast burns are pretty impressive. I wonder if we'll start seeing some serious build ups with them?