Help with 86 Iron Heads replacement
Thread Starter
Intermediate
Joined: Mar 2009
Posts: 35
Likes: 0
From: Newton Ks
Help with 86 Iron Heads replacement
I have a 1986 corvette with the infamous #462624 Heads. Are these heads really as bad as everyone says? And if so what can I replace them with? Is there another head that can be used with out alot of modification? My proublem is that one of my heads was damaged while trying to get a plug out for the sensor. It cracked. I was wanting to try and just replace the head that is cracked. But I am haveing trouble finding a replacement. Any info will be greatly appreciated.
Team Owner
Joined: Jan 2003
Posts: 20,324
Likes: 250
From: Summerland B.C. Canada
One of the vette wreckers would have one, but you could replace them both with the 128 or 113 heads.
Here is a older post for 113's for sale, almost a month old and no replies, so the price might be a little better now.
http://forums.corvetteforum.com/c4-p...s-113-l98.html
Here is a older post for 113's for sale, almost a month old and no replies, so the price might be a little better now.
http://forums.corvetteforum.com/c4-p...s-113-l98.html
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
The 624's are a thinwall casting, and are prone to cracking. I am assuming this may be around the exhaust seats. Changing to a 113 aluminum head will not gain you much, other than weight savings. I have heard the iron heads flow a little better than the 113's. The 113's have a 58cc combustion chamber and will raise the compression on your flat-topped pistoned engine to close to 11:1 compression, which may be a problem. Your 624's have a 76 cc chamber. I would recommend a set of 882's in iron if you are on a budget (76cc). You should be able to find a replacement set of 624's really cheap, try Ebay. Edelbrock has E-street aluminum heads in 72cc for 850 bucks. I think these might be lacking an EGR passage, though.
Le Mans Master
Joined: Nov 2009
Posts: 6,882
Likes: 234
From: Bangkok, Thailand
I have an L-83 with the same heads so I've looked into this a lot.
The most cost effective direct replacement heads I've found are these: http://www.summitracing.com/parts/SUM-152123/ $620 for a pair, ready to go.
Beyond that if you go aluminum, you might as well go with either AFR 180's ot Trick Flow Super 23's. Either one is available with a suitable comustion chamber size and they both have an exhaust crossover so you can keep all your smog stuff. That's also important because your computer tune includes provisions for the operation of the EGR system.
Summit also has a set of aluminum heads with an exhaust crossover for $995 (http://www.summitracing.com/parts/SUM-162108/) but no info on performance or flow ratings. You could always call and ask though.
Good luck with it!
PS: just saw the fine print on the aluminum heads: "flowing 240 cfm at 0.500 in. lift"
The most cost effective direct replacement heads I've found are these: http://www.summitracing.com/parts/SUM-152123/ $620 for a pair, ready to go.
Beyond that if you go aluminum, you might as well go with either AFR 180's ot Trick Flow Super 23's. Either one is available with a suitable comustion chamber size and they both have an exhaust crossover so you can keep all your smog stuff. That's also important because your computer tune includes provisions for the operation of the EGR system.
Summit also has a set of aluminum heads with an exhaust crossover for $995 (http://www.summitracing.com/parts/SUM-162108/) but no info on performance or flow ratings. You could always call and ask though.
Good luck with it!
PS: just saw the fine print on the aluminum heads: "flowing 240 cfm at 0.500 in. lift"
Last edited by mcm95403; Nov 17, 2010 at 12:25 AM.
Drifting
Joined: Mar 2009
Posts: 1,253
Likes: 4
From: East Wenatchee (2hours from n e where) WA
I have been lookin at a little cheap love for my l83 as well. For me it has got to be an aluminum head. The compression numbers that I have been using are;
L83,
deck .025
gasket .025
chamber 76
valve relief 3 (? the variable that I used to get 9-1cr)
quench .050 (really dont want to increase this with a thicker hgasket)
A 64cc head works out to 10.27-1. Switching to the 113's 58cc chamber works out to 11-1. But, if you add 7cc to the chamber (deshroud and blend sharp edges) it works out to 10.15-1 doable especially if you ditch the pathetic L83 cam and bleed of a little dynamic comp. my thoughts are there will be very little to be found if keeping the stock heads intake or cam. The Cross Fire throttle bodies should flow enough to support this but tuning this setup is a huge unknown for me. Pocket porting the 113s as per David Vizzard is a must.
finding a good set if 113's, porting and rebuilding could bring the cost so close to a set of after market heads that it will not make sense to do the 113's
Hopefully I am not hijacking here.
What do you guys think?
L83,
deck .025
gasket .025
chamber 76
valve relief 3 (? the variable that I used to get 9-1cr)
quench .050 (really dont want to increase this with a thicker hgasket)
A 64cc head works out to 10.27-1. Switching to the 113's 58cc chamber works out to 11-1. But, if you add 7cc to the chamber (deshroud and blend sharp edges) it works out to 10.15-1 doable especially if you ditch the pathetic L83 cam and bleed of a little dynamic comp. my thoughts are there will be very little to be found if keeping the stock heads intake or cam. The Cross Fire throttle bodies should flow enough to support this but tuning this setup is a huge unknown for me. Pocket porting the 113s as per David Vizzard is a must.
finding a good set if 113's, porting and rebuilding could bring the cost so close to a set of after market heads that it will not make sense to do the 113's
Hopefully I am not hijacking here.
What do you guys think?
Last edited by Crepitus; Nov 17, 2010 at 01:38 PM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
May as well go aftermarket as suggested. Iron or aluminum, stock castings wont get you any power increase youll see unless you throw a whole bunch of $ at them and you still have a used head. Its not a BAD thing but think for the $ most would rather have new. Only good thing about stock heads is you know everything will bolt on perfectly the first time.
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Drifting
Joined: Mar 2009
Posts: 1,253
Likes: 4
From: East Wenatchee (2hours from n e where) WA
I just reread the OP and realized he has a 86 L98 with the 624 head. Dooh! I will lay off the xfire stuff. Now back to your regularly scheduled programing....
The Summit claims a flow of 240@ .500 a stout improvement over the 624, 128 or 113 that all seem to flow about 200 @ .500 in stock config.
The Summit claims a flow of 240@ .500 a stout improvement over the 624, 128 or 113 that all seem to flow about 200 @ .500 in stock config.
Intermediate
Joined: Oct 2009
Posts: 47
Likes: 0
From: Glenwood Arkansas
My 86 is also has "624" heads, I have been debating buying aftermarket heads, or bolting on a set of 041x heads I have here. Money would be about the same between buying aftermarket or taking the 041x's for cleanup/refit with beehives, new valves , studs/guideplates, etc. Aftermarket would likely be cheaper in the long run.
