Cheap head upgrade
Thread Starter
Safety Car
Joined: Dec 2004
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From: San Diego CA
Cheap head upgrade
Figuring that the stock heads are horrible for performance anything is probably better, but I don't exactly have the money to shell out for a pair of vortecs + an intake manifold.
So my question is what's a good flowing head casting? I was looking at some old 64cc chevy heads that are like $100 - $300 for a pair of em, some already ported and such. I'd prefer a 68cc chamber but only aftermarket heads come in those sizes, apparently.
Suggestions please.
Just want to get a bit more compression and flow on my '81 so there's more oomph. 
So my question is what's a good flowing head casting? I was looking at some old 64cc chevy heads that are like $100 - $300 for a pair of em, some already ported and such. I'd prefer a 68cc chamber but only aftermarket heads come in those sizes, apparently.
Suggestions please.
Just want to get a bit more compression and flow on my '81 so there's more oomph.
Race Director
Joined: Aug 2004
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From: Duvall, WA
L98 auminum heads are pretty cheap and, while they don't flow the best, they do provide a nice amount of torque. That's what Chevy uses on the ZZ4 crate engine. They are 58cc so your new compression ratio might warrant a higher octane fuel than you are using now.
Thread Starter
Safety Car
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From: San Diego CA
Originally Posted by rcread
L98 auminum heads are pretty cheap and, while they don't flow the best, they do provide a nice amount of torque. That's what Chevy uses on the ZZ4 crate engine. They are 58cc so your new compression ratio might warrant a higher octane fuel than you are using now.
Melting Slicks
Joined: Dec 1999
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From: Mid West
Cruise-In III Veteran
Originally Posted by Kalway
I was thinking about those but it dawned on me that my compression is already ~8.5 or 8.6:1 so those would bump me to like 10:1 or more. Too high for my taste. I was aiming for mid 9s:1
Le Mans Master
Joined: Jul 1999
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From: Sewell NJ
Your compression ratio is based on the use of steel shim gaskets. If you use composite gaskets you will drop the compression ratio. Try going with .060 compressed gasket thickness and you should be in the range you want.
Race Director
Joined: Aug 2004
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From: Duvall, WA
My L48 had 8.5 compression from the factory. I bolted on the 58cc L98 heads, used a .058 compressed thickness gasket and have had no compression related problems whatsoever. I am very happy with the improved performance.
Team Owner
Joined: Sep 2003
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From: eville in
Originally Posted by rcread
My L48 had 8.5 compression from the factory. I bolted on the 58cc L98 heads, used a .058 compressed thickness gasket and have had no compression related problems whatsoever. I am very happy with the improved performance.
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Race Director
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From: San Jose CA
Originally Posted by Kalway
Suggestions please. Just want to get a bit more compression and flow on my '81 so there's more oomph.
Just want to get a bit more compression and flow on my '81 so there's more oomph. If all you want is 20-30 more horsepower, than this truly is the way to go. I suggest putting the money you have now aside and waiting for a better set of heads - you won't regret it.
The other suggestions here are on the money though - I'd stick with 10:1 and up the cam if you decide to go with L98 heads, you'll be able to run 10:1 compression with a slightly more aggressive cam and avoid pinging easily.
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From: San Diego CA
Looks like the general consensus (sp?) is for the L98 heads with a thick head gasket. I'll look in to em.
To note a few things, I've already got a beefier cam in it. Summit 1103 it's not a monster or anything but it is better than the edelbrock performer and tons better than the stock cam that went flat on me. To give you an idea, after the engine was rebuilt (with the ~8.5:1 comp ratio) and with the new cam it dynoed 181 rwhp with the stock original exhaust on. Now it has headers and sidepipes so it's probably in the low 200s at the wheels.
I figure mid 200s at the wheels should be perfect for autox.
To note a few things, I've already got a beefier cam in it. Summit 1103 it's not a monster or anything but it is better than the edelbrock performer and tons better than the stock cam that went flat on me. To give you an idea, after the engine was rebuilt (with the ~8.5:1 comp ratio) and with the new cam it dynoed 181 rwhp with the stock original exhaust on. Now it has headers and sidepipes so it's probably in the low 200s at the wheels.
I figure mid 200s at the wheels should be perfect for autox.
Race Director
Joined: Jan 2000
Posts: 12,399
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From: San Jose CA
Originally Posted by Kalway
Looks like the general consensus (sp?) is for the L98 heads with a thick head gasket. I'll look in to em.
To note a few things, I've already got a beefier cam in it. Summit 1103 it's not a monster or anything but it is better than the edelbrock performer and tons better than the stock cam that went flat on me. To give you an idea, after the engine was rebuilt (with the ~8.5:1 comp ratio) and with the new cam it dynoed 181 rwhp with the stock original exhaust on. Now it has headers and sidepipes so it's probably in the low 200s at the wheels.
I figure mid 200s at the wheels should be perfect for autox.
To note a few things, I've already got a beefier cam in it. Summit 1103 it's not a monster or anything but it is better than the edelbrock performer and tons better than the stock cam that went flat on me. To give you an idea, after the engine was rebuilt (with the ~8.5:1 comp ratio) and with the new cam it dynoed 181 rwhp with the stock original exhaust on. Now it has headers and sidepipes so it's probably in the low 200s at the wheels.
I figure mid 200s at the wheels should be perfect for autox.
Thread Starter
Safety Car
Joined: Dec 2004
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From: San Diego CA
Oh I still need casting numbers for the heads 
I'm just looking on ebay right now but will call up my engine builder and probably some junk yards on monday.
Are #461, #434, #601, or #128 good castings? I know 10088113 is the Corvette L98 casting number exactly, but what about the formers?
I'm just looking on ebay right now but will call up my engine builder and probably some junk yards on monday.
Are #461, #434, #601, or #128 good castings? I know 10088113 is the Corvette L98 casting number exactly, but what about the formers?
Safety Car
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From: Jersey Shore Exit 98
Originally Posted by GDaina
Check GM Perfrormance parts, they dropped prices on aluminum heads..fully assembled, around 375.00 but can't remember which head.
Thanks
Jim
Melting Slicks
Joined: Mar 2006
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From: Orange Park Fl
Let me add another vote for "save your money and get something good!" You can pick up a brand new set of fully assembled Dart Iron Eagles delivered to your door for around $800. They bolt on like stock, flow great and have efficient fast burn combution chambers. God bless, Sensei
Last edited by a1sensei; Sep 16, 2006 at 06:59 PM.
One gear at a time
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CI 8-9-10 Veteran
St. Jude Donor '07-'08-'09
I agree with those recommending you wait until you can afford a decent set of aftermarket heads. The TFS heads are a good bang for the buck, and clean-up nicely.
Here is a thread with flow info from two different pairs of factory heads I have. Both have been ported. Factory heads can be made to work, but it isn't cheap. In the hands of the right porter, they will outperform many street, aftermarket heads... for about the same price as new heads. Mildly ported heads are a lot cheaper to build, but at the end of the day, you will probably be wanting more.
http://forums.corvetteforum.com/show....php?t=1501001
Here is a thread with flow info from two different pairs of factory heads I have. Both have been ported. Factory heads can be made to work, but it isn't cheap. In the hands of the right porter, they will outperform many street, aftermarket heads... for about the same price as new heads. Mildly ported heads are a lot cheaper to build, but at the end of the day, you will probably be wanting more.
http://forums.corvetteforum.com/show....php?t=1501001
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Originally Posted by GDaina
Check GM Perfrormance parts, they dropped prices on aluminum heads..fully assembled, around 375.00 but can't remember which head.
Checked sites at Pace, SDPC & Sallee (now Gilbert).
Found NO GM/GMPP assembled aluminum sbc head for under $500 each ... checked the specials/closeouts and the usual L98 & fastburn ... no luck.
I did not look for LSX heads ... not many C3 fitted w/ LSX.
I did not look for BBC heads ... they're typically higher $ than sbc.
Would the esteemed mod please follow up & substantiate?