Aluminum vs Iron.




As some of you know, I am a man on a budget. I went and got this thing called a wife. Yeah, I know....



But anyway, things are actually starting to come along in my little project. It's an L48 76'. Anyway, my question today is, pros and cons of aluminum heads vs iron ones. I know that weight and heat are the main factors, but honestly, heat is not a problem, and neither is weight, for me. I am not looking to build a race motor, and honestly, I'm not even looking to get much more than 280-300 hp to the rear wheels, or around 350-400 at the crank, what have you. Before I blow much more money on a cam, I want to save up for some closed chamber heads, as mine are open chamber. I'm not looking to go to any extreme compression, but at the same time, 8.5 is a tad low, even for a grocery getter car. I have read some of you guys saying that if you had it all to do over again, you would have spent more money and gotten the aluminum heads. Why? Any help or advice?

 

I'm a huge fan of the Vortec head and intake swap.

The heads can be had cheap from a salvage yard, and a machine shop would only need a few hundred for the minor work you'd want to do. Then a cam and lifter combo from Summit for less than $100, a Vortec manifold for a little over $100, and assuming you don't need or care about the EGR, you'd have about 9.5:1 and around 300 HP at the wheels.

There are some other minor details, but you can effectively do the Vortec swap for around $1000.

 

The vortec heads and intake swap can be argued one of the best proformance upgrades for the money. I have the aluminium vortec heads and couldn't be happier. There are folks here that know more about the pro's and con's than I do. But, sounds like you have a good handle on what they are. I think beside aluminium being able to squeeze more compression and the obvious weight differences that's about it. But I'm no expert. The reason I went with aluminium was that I got a great deal on them. Otherwise, I probably would have went with cast iron. But like you said, some folk wish they had gone with aluminium and on my budget, I knew I would have one shot to do it right with no regrets. Glad I did.

http://i245.photobucket.com/albums/g...memountain.jpg

 

As DB already said, one of the more economical and popular replacement heads these days is the GM Vortec head with 64cc combustion chambers. These heads will require the use of a Vortec style intake manifold, center bolt pattern valve covers, self aligning rocker arms and that your Q-jet carb be converted to an electric choke for your '76 application since these heads do not have a heat crossover.

Two of the most popular intakes for the Vortec heads that will still accept a stock Q-jet carb and fit under a Corvette hood are the Edelbrock Performer and the Weiand 8121. The smaller chamber heads combined with a thinner head gasket like the Fel Pro 1094 at .015” will provide you with a nice quench distance of approximately .040” and a resultant compression ratio of approx 9.5:1. This combined with a short duration cam such as the Summit K1103 cam kit with duration values @.050” being 214/224, the Dynamic Compression Ratio (DCR) ends up being 7.7:1. Another popular cam is the Comp 262, both will get you to that 300 crank HP mark. If you want to stay GM, the L-82 cam advanced 4 degrees will have a nice broad power range and work well with your new found compression ratio without any detonation issues.

You can buy new modified Vortec heads for a higher lift cam for around $600 from Scroggin Dickey. If you want aluminum heads, the Brodix IK180s are hard to beat at $1K and do not require a Vortec intake or center bolt valve covers.

 

What is the intake centerline of an L-82 cam?

 

ICL for the L82 cam is 114, very similar cam to the "151" cam which is has a ICL of 110. Its basically a retarded version of the "151" for the added stroke of the 350 with a bit more lift.

Hammyjoe, aren't your heads technically called "Fast Burns" and not Vortecs.

 

Cool, thanks.

What is the lobe seperation for the L-82?

 

The ICL, EML and LSA are all on 114 degrees.

 

Technically, yes. But it's my understanding that they are still vortecs.

 

What is the easiest way to advance the camshaft timing? I will be replacing my timing chain set also.

 

Find you a set of double humps with the accessory holes. They are 64 cc chamber and lots of them are 2.02/1.60's and maybe a little bit bigger cam. I know the vortechs are suppose to flow a little better, but if you are on a budget you can use your same intake and valve covers. Just depends on how much money you want to spend.



greg

 

The only problem is, even now, they are hard to find, and likely have had several valve jobs over the years, some Bubba porting jobs, and may need several hundred in machine work to make useable again. Unless you can find a ready to bolt on set cheap, I'd go Vortec, or maybe some of the Dart or World Iron heads. Its not hard to spend $5-600 dollars reworking a set of heads.

 

If you don't want to put $5-6 hundred dollars in a set of heads, what do you think new Vortechs, Dart or World Iron heads cost you? Plus with the Vortechs you have to change the intake and valve covers. I have nothing against the Vortechs they are good heads. Just thought he was trying to do it on a budget. I have found several nice sets of double hump heads you just have to look for them. What is cheaper, $500 pair of double humps or new Vortechs, intake and valve covers? Remember the key word he said..........I'm on a budget.




greg

 

Okay, here's what I found in about twenty seconds.

1997 Chevy 1500 Used Cylinder Heads 350 (5.7L) $75 EA
American Truck & SUV
Sevierville, TN
866-749-7418

That's $150 for the heads...

Polished Vortec Manifold:
http://cgi.ebay.com/ebaymotors/SBC-C...em110226587371

Okay so far we're at $300 give or take.

Valve covers, custom aluminum covers not withstanding, are under $20 in most cases. So we'll call our total to this point $325.

Add a set of self aligning rockers, a new timing set, seals and gaskets, fluids, cam and lifter combo, and you will probably be under the $600 mark.

That seems right inline with a low budget, when you consider you get about a full compression point and around 100 HP.

 

Since you are not looking for max hp, you could look for a used set of L98/zz4 heads. They are just as cheap as the vortecs, your intake will fit but you will need centerbolt valve covers.

 

Yeah..it was early. Fixed.

 

The $500 I was mentioning for the set of double humps was after they were gone through. You are listing used Vortechs for $150 and you can find good double humps for $2-300 all the time, so that puts it $300 under yours. We could argue this all day long...........................I was just trying to give the OP another option thats all.




greg

 

Thanks for all the info. I already bought the eddlebrock performer intake off of ebay for 40 bucks, lol. I don't care if it's dirty, I'm just gonna paint it black anyway.


I am looking at the similar performer eddlebrcok performer cam and lifter set for anouther 120 bucks, new from summit. Not sure if buying a used cam is wise. Advice on that?

My neighbor suggested Crane Cams' Fire Ball 2 cam shaft, but I can't seem to find it on their website. He is a mechanic, and has helped me a lot......but is he crazy, or is that a discontinued cam? And if it is real, is that advisable?

And last, I already have strait pipes with no cats, and I bought the 90 dollar headers off ebay. The pipes are 2 inch, though. It's what came with it. Kinda sucks, as I see a 2.5 inch being necisary.

The last two pieces of the puzzle are the cam and valve heads. And I figured that these two need to be bought with each other in mind...


So the consensus is, then, that due to my more limited power goals, getting aluminum heads is not such a big deal?

 

And yes, I have a pretty damn good machine shop right down the street from me, they pressed all of my bushings for me (which REALLY sucked, lol $$$) so I WILL be buying used heads, DB. Thanks for that bit.

 

The Edelbrock performer cam sucks, and I wouldn't be too concerned about needing aluminum heads. Man, I haven't hear the words Crane Fireball for about 20 years!

I take it the Performer intake is a non Vortec intake. Look at Summit's house brand 67cc non Vortec cast iron heads if you are on a budget, $585 and you won't need to spend another $250-$300 on new heads to have them refurbished like you will with used heads.

You don't want to get crazy with a cam that will be too big for this little motor. The GM "151" cam would be a nice little cam or the Sum K-1103 DB mentioned would be fine as well.

Good Luck,
Scott