Are the GM PN 93438649 heads a reasonable replacement for the stock 78 L-82 (462624) heads? I'm not looking to do a performance build at this point but we will see how long that last..

 

Yep, they're a basic "Stock Replacement" SBC head. They're not bad heads, and can be made better with a little bowl work.

For the price, around $400/head, I'd consider the World Products S/R or S/R Torquers. These heads have a ton of potential with some bowl work but can still be bolted on as-is.

Summit also makes a set of S/R-type heads...but I've used a couple sets of these and wasn't super impressed - they need bowl work right out of the box (there's a HUGE ledge right under the seats) and come with umbrella-type valve seals. The seats were also lousy IMHO.

 

Just to confirm, I shouldn't put any money into rebuilding the stock 462624 heads correct?

 

Well, you'll get a lot of different answers to that question - this is mine

There are two aspects to this:

First, price. It used to be that parts were expensive and machine work was cheap - so we rebuilt heads vs. buying new ones. Overseas manufacture has turned this around completely - so often the cost of rebuilding a set of heads is higher than buying new ones. Figure on around $450/pair for a straight rebuild of SBC heads with new guides, valves and springs...and compare that to the cost for a new set of S/R heads or a set of Vortecs. As an aside, this is also true of connecting rods, cranks, etc.

Second, performance potential. Virtually any of the S/R-type heads are limited to around 300-350 horsepower - that's a very big generalization and so more than a bit suspect...but a pretty good rule of thumb. With some porting work we can extend this to around 400 HP or so...but once again we run into cost comparisons where the money spent porting heads can buy a better head right out of the box. If you're willing, a home porter can do a pretty decent job.

A singular exception is the stock GMPP Vortec heads that flow better than all of the S/R type heads and right in there with many of the bottom tier aftermarket performance heads...and are dirt cheap. For making around 1.2HP/CID or so, Vortecs are a gift from the General - cheap power. But these require a Vortec-specific manifold and center-bolt valve covers, which increases the cost another $250 or so...still a great deal.

Maybe someday the General will drill the stock Vortecs for both new and old style manifolds and valve covers like they do on their other Vortec performance heads...that would be perfection.

So, if you're on a budget and not seeking power beyond about 300 - 350HP then IMHO a good stock rebuild on the stock heads is fine. If you think you might shoot beyond that number and can afford them, the aftermarket S/R heads are a better buy.

Maybe more than what you were asking - but there you go

 

Get the vortec heads.



As durango can show you, they can be had for as little as 150 apiece, used. Buy em, clean em up, and get your vortec style aluminum intake.



Let's face it, you were going to get an aluminum intake anyway, right?


So may as well make it a vortec style bolt patern. Get one from summit, 150 bucks.



Now you are set. You don't want much power, fine, stick with what you got.


Later on down the road, you want more power?


All you gotta do is get a bigger cam, and the vortec heads will love it, and you.

 

So when shopping around for used Vortec heads, it there a limit on the mileage on them I should shoot for? I found set of 906's with ~ 35K on them...

 

Dunno what type choke OE '78 L82 has?

x649 head does NOT have a heat riser to pass hot exhaust thru intake manifold beneath plenum ... thus won't operate divorced CHOKE ... and neither do vortecs.

 

I would convert to an electric choke if I went 649's or the Vortec's.

 

Get some iron vortecs ... don't worry about mileage ... it's the cracks that matter ... and head cracks are NOT mile-dependant ... whatever used head you choose ... make certain you have them checked by an expert for cracks etc.

-edit- BTW ... with L82 FLATTOP pistons ... and any 64cc chanber (like vortec) you WILL be near 10:1 scr.

 

Don't forget that with Vortecs you need self-aligning rocker arms. You can use your original pushrods.

 

By the time you get a used set, clean 'em up, get 'em fluxed...you're within striking distance of a new set

There are good aftermarket rockers available from the standard vendors like Crane, CompCams, etc. - but the General has a set under P/N 12495490 that sell for about $60.

 

This is my problem. Every other day I think "alright, I need to get get some Vortecs and I'll have them for under $300, get them cleaned up and we're good to go." Then I realize... "but new ones are only $600." And then I think... "well SD sells the machined ones for 1k, including the intake manifold." And my next thought is... "well ****, for around 1-1.5k I should get some decent aluminum heads!" And then I've come full circle, starting over in a few days with the used Vortecs for a couple hundred....

 

It all depends upon what you will be happy with. 300 - 350 hp, stick with the rebuilt vortecs. 400+ then start looking at quality aftermarket.

 

*chuckle* Been there.

The stock Vortecs are fine for lift up to .475 max - so unless you're looking for more, just stick with the stock heads. The heads don't flow much past .500 or so...so the big lift upgrades don't buy a lot.

 

I remembered reading an article about Vortecs that said - "Casting number 10239906 should be avoided".

http://www.chevyhiperformance.com/ho...458/index.html

 

The next planing question. What cams are you guys running with stock vortecs? It looks like from what I can tell, I should plan to stay under .475 lift. The L-82 cam 222/222 seems reasonable but the .480 lift is tight.

 

You MUST stay under .475 lift with the stock heads.

The stock L-82 cam (3896962) is .450/.460 and it's a decent cam.

Any other suggestions take the full specs - trans, gears, use, etc.

 

Thanks for the info. I'm sticking with my stock 4 speed (M20) and 3.70:1 rear end. Dual exhaust with stock manifolds. As far as performance goals, I'm shooting for the 300HP mark with strong low end torque. Not planing on running it at the strip just an occasional daily driver with some muscle.

 

IMHO, the stock L-82 cam isn't a bad choice to stick with. If you want to replace it as part of the top it's available from Crane.

I'd be happy to DD advanced some other combos...but honestly I think I'd stick with what you have given your usage and targets.

It's always worth a call to CompCams CamHelp or other manufacturers to get their take. Unless your power targets change, I'd stay away from the roller-cam profile flat-tappet cams like the CompCams Xtreme Energy.

Finally...for your power targets new heads aren't really required, but we've covered that and it's your call

 

It there any reason I shouldn't go with the Summit 1103 cam? It looks like a good fit for Vortec's with 214/224 and .442/.465 lift.. I picked up a set of 906's heads, matching Edelbrock performer intake and stock valve covers so once I settle on a cam, I'm set..