Hi Y'all. I'm trying to figure out what it's going to take to get my s/b up to 9.6 compression with 76cc 882 heads. I have the bucks to buy the summit steel heads 64cc but I’m not sure if I should go with the vortec or the stock ones. The truck is a 1981 GMC 1/2 ton 4x4 so it needs to pass smog in this state. What heads will give me better performance. The summit brand heads are 550 bucks till the end of the month then they go up 100 bucks and if I go with the vortec heads I’ll need to buy an intake as well. So that money for the intake will come out of my bottom end rebuild, like cutting corners on pistons. What do y'all think is the better way to go?

Thanks Bill

IMO go vortechs. theyre advertised 64cc heads but theyre more like a 60. and from 76cc's that'll give you the comp that your seeking after

vortecs run really well but if you buy used make sure the owner will stand behind them cause they crack real easy!

So if I keep my stock bottom end Ill be able to get the compression up to 9.6 just with the vortec heads ??? Sounds good to me. I was going to put flat top pistons in her and go with the summit 64cc steel heads, keeping my crank and rods. Of course I'm going to change the cam but I'll need some help with that information from y'all.

Thanks Bill

no prob. good luck with the build

If I buy a brand new set and it over heats the heads could crack. ???? Hmmm think I might stay with the summit heads. I do a lot of 4 wheel-in and she does have a tendency to heat up a bit when I get stuck in the mud, you know sitting still and rocking her back and forth.

Bill

I'm not sure I fully understand the question - are you overhauling the engine, or you're looking to raise the CR by bolting on new heads? If you're looking for hypereutectic pistons, there are a lot of choices that will work with any head selection.

Swapping from a 76 cc to 64cc head will raise the CR approximately 1.1 points.

A 1 point increase in CR is worth maybe 3% power increase on an engine that's making around 1 HP/CID...so unless you're stuck on increasing the CR there are other ways to make more power - and for less money.

I have no idea what the comment is regarding Vortec heads and cracking; I've never heard of this happening. They certainly don't "crack real easy".

More information on your usage and budget would help. Usage drives the cam selection, cam drives the head and the rest of the engine is built around those two pieces.

ive never experienced the cracking of vortecs real easy. and mine has gotten pretty hot in the past. there are 2 casting of the vortecs i believe the 062 or something close to that is the good casting to get

The rise in compression on paper maybe 3%, but the true advantage is the ability to use more cam...with the better heads, hence increasing the HP by way more than 3%

It's a complete rebuild. I bought the engine thinking it had a rod knock and when I tore it down there was nothing wrong. So I figured I'd build it up and try to make more bottom end and mid range. Now I know I can put a cam in it but i'm looking for a little more than that and thats why I was thinking pistons and heads. As for buget i'd like to keep it under 1000 if possible. Buy the way it's not going into the 72 listed below it's going in a 1981 GMC 1/2 ton L/B 4x4.
Buy the way it's not going into the 72 I have it going in a 1981 GMC 4x4 1/2 ton L/B
Bill

The rise in compression on paper maybe 3%, but the true advantage is the ability to use more cam...with the better heads, hence increasing the HP by way more than 3%

Completely agree that the benefits of CR as part of the overall design has significantly more impact - especially as the build moves beyond 1 HP/CID.

If there's nothing wrong with the bottom end I'd just do a cam swap and some better heads and leave it - that'll use all of your $1000 by the time it's all back together.

In your opinion would it be better to go with Iron heads or aluminum. The iron heads will be the summit brand 152123 $585.00 a set, or go with the aluminum ones on e bay, link below. Remember this is going into a truck at 5000 feet elevation. Also I don't have the confident in myself or enough engine building experience to make this decision without input from people that have been there.


http://cgi.ebay.com/ebaymotors/NEW-SB-CHEVY-CHEVROLET-PERFORMANCE-CYLINDER-HEADS-190CC_W0QQcmdZViewItemQQ_trksidZp1713Q2em153Q2el1262QQcategoryZ33617QQihZ023QQitemZ360027837974

Bill

I was interning at a machine shop in sacramento, and I heard that Vortecs "weren't too good" which for a machinist means they crack easier, and are near impossible to fix. just my understanding on them.

anything flow better than stock.
summits heads iirc are rebadged vortech heads...

mind you vortech is still and emission head as well iirc

peak flow is one thing avg flow is another. yes vortech have a high peak air flow. both dart and world have a high/flater curve than vortech... kinda like which motor would want peakhp of 525 avg hp 450 or peak 500 avg 475? hope that makes sense

and make more power on a same setup than vortech

IMHO i would take a pair of ~180cc s/r torquers or iron eagles over vortechs any day

got to pay to play and you get what you pay for....

I think the summit heads are a fuellie/camel head recasting.
Vortecs would be just fine. I havent used a set but a lot of friends have with good success. The only problems with them can be...intake gasket sealing and they require a different intake and center bolt valve covers. They are a thinner casting then an aftermarket head,
Those Ebay heads actually work quite well(if they are assembled correctly). They are cheap Chinese castings that don't have very good QC., but if assembled by someone who knows what their doing they work real well. I wouldn't hesitate using them on a street car(especially at altitude)

So your saying that iron would be better than aluminum and that the summit heads are iron vortec heads from GM but are being sold as summit. As fare as money wise the s/r torquers or iron eagle are the better way to go than the summit heads.
I was told that if I had a choice between aluminum and iron to always go with aluminum. Keep in mind the engine is smog headed and will need to pass smog in the future

Bill

So your saying that iron would be better than aluminum and that the summit heads are iron vortec heads from GM but are being sold as summit.
to me it is funny the summits iron head have the same spec as gm iron vortech heads. go figure
As fare as money wise the s/r torquers or iron eagle are the better way to go than the summit heads.i would agree with that statement

I was told that if I had a choice between aluminum and iron to always go with aluminum.depend on the application pro/con both ways

Keep in mind the engine is smog headed and will need to pass smog in the future

Bill

alluminum is great and has it pros and cons over iron. and vise versa

as for the the need for emision you will be hard pressed to find a oem replacement head that is emision compatible.

s/r torquers are emisions and 50 state as well.

Summit head in question above

http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2D152123&N=700+115&autoview=sku

They look like fuelie/camel hump remakes...heres their discription(also the intake manifold gasket is non vortec)
Small block power for less!
Think you have to scour the local bone yards to find a decent set of GM's old double hump or fuelie cylinder head castings? Not true. In fact, we've brought back classic Chevy performance in a big way with these ready-to-run heads for small block Chevy. Our versions of the popular GM cylinder heads offer great performance for less than it would cost to rebuild an old set of double hump castings.

You may be able to keep within your emissions standards with the head swap, but when you chase the power with the cam, you're probably gonna drop out of spec, depending on how strict they are in Reno.

Anyone in the Reno area that’s built an engine within these specs? please e mail me. I should just sell the darn thing and buy an older truck without the smog on it. It's hard to let go a clean one-owner truck that just needs a paint job, no rust, no bondo, and no dents anywhere. The only problem is the year.

Bill

just bolting on vortec heads is a 30-40 hp gain not necessarily because of the compression gain but because of the amazing flow characteristics of the head.

it has allot to do with the swirl and tumble of these heads