Will these heads work???
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Racer
Joined: May 2006
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From: Urbana OH
Will these heads work???
I have an 86E and was wondering if the 87 aluminum heads would mate up or if not what mods I would have to do to make them work.
Thanks so much for your help.
Semper Fi
Thanks so much for your help.
Semper Fi
Thread Starter
Racer
Joined: May 2006
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From: Urbana OH
Safety Car
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From: Poop land
Well, I know the heads will bolt on just fine but correct me if I'm wrong, but I think you'll also be needing the later intake since the early pre-87 TPI intake bases had a slightly different bolt pattern. That, or you can drill it to fit the later style heads.
Racer
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Originally Posted by kopbet89c4
correct me if I'm wrong, but I think you'll also be needing the later intake since the early pre-87 TPI intake bases had a slightly different bolt pattern.
Last edited by C4Techie; Feb 13, 2007 at 07:59 PM. Reason: To add: Except...
Safety Car
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From: Salem NH
The old parimeter bolt heads have the original style for the center bolts...
The later (86/or 87) have the new style, which puts the center 4 intake bolts at a 72º angle.
The 92-96 have an LT1 intake. If the car came factory with an LT4 (not sure if any did) it would be different as the bolt pattern is closer to vortec, and the ports are raised.
-- Joe
Last edited by anesthes; Feb 14, 2007 at 10:48 AM.
Racer
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Originally Posted by anesthes
Umm. Same "pattern" as in the holes are in the same spots, but you will NOT get a late intake to bolt to early heads without slotting the 4 center holes.
The old parimeter bolt heads have the original style for the center bolts...
The later (86/or 87) have the new style, which puts the center 4 intake bolts at a 72º angle.
The old parimeter bolt heads have the original style for the center bolts...
The later (86/or 87) have the new style, which puts the center 4 intake bolts at a 72º angle.
Originally Posted by C4Techie
All C4 Corvette intakes have the same bolt pattern.
Originally Posted by anesthes
The 92-96 have an LT1 intake. If the car came factory with an LT4 (not sure if any did) it would be different as the bolt pattern is closer to vortec, and the ports are raised.
-- Joe
-- Joe
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Thread Starter
Racer
Joined: May 2006
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From: Urbana OH
Am I going to see much if any gain with these heads without doing a P&P or valve job on them. They are going to get either 1.6RR or 1.6Roller tips I haven't quite decided yet. I was told that these heads would give me a slightly higher compression over my iron heads and probably give me a few pones like possibly 5-10. I know I wouldn't feel it but I was just wondering if I can expect a few extra ponies on top of droping 40lbs of the front of my car. I'm more worried about auto-xing so I like the weight distrabution gain :-D.
Also one last thing how hard would it be to just pull my old heads off and drop these in? Should I just go ahead and have them replace the timing chain as well? I know I'm going to be getting all new gaskets and the timing will need to be redone but other than that will the pushrods just stay in place so I can just pull the old heads off and drop these on??
Thanks everyone for the posts.
A greatful Marine
Also one last thing how hard would it be to just pull my old heads off and drop these in? Should I just go ahead and have them replace the timing chain as well? I know I'm going to be getting all new gaskets and the timing will need to be redone but other than that will the pushrods just stay in place so I can just pull the old heads off and drop these on??
Thanks everyone for the posts.
A greatful Marine
Le Mans Master
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From: One day you're a Comet...the next day you're dust... Arkansas
If all you are going to do is a head swap and yours are O. K. it doesn't seem worth it to me. But, if you would install a good used set of 113 heads, a good cam, and full RR's with springs, that would give you a nice pop even without any porting. JMO
Thread Starter
Racer
Joined: May 2006
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From: Urbana OH
Thanks
Safety Car
Joined: May 2006
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From: Salem NH
That is not correct. As I said,In 1987 Chevrolet changed the angles of the center bolt holes in the cast iron heads which were never used on Corvettes. The 1984, 1985, and 1986E, cast iron, #624 heads, with the perimeter valve cover mount, has the same EXACT intake manifold bolt pattern and angles as the #128 and #113, aluminum, center bolt valve cover mount, heads used on all the remaining years of Corvette L98s, 1986L through 1991. Check it out!
LT4 engines were available in the 1996 Corvette. The manifolds are considered an improvement over, and interchangable with, the LT1 mainifolds. They do not use the vortec ports or bolt pattern. I sincerely believe the LT1 and 4 maifold bolt patterm and bolt angles are the same as all early Gen I SBC engines, but I admit I am not positive. There are too many LT manifolds being swapped onto L98s for me to believe that there is much of a difference. And I cannot accept the word of a single individual that is so very wrong about the Corvette L98 manifolds.
the ports are slightly different. (which is not way different). so who knows. *I* have never touched one.
I do know, when summit was selling the LT4 intakes, they also sold the LT4 heads - so I don't know if they were needed or not.
http://www.grandsportregistry.com/lt1vslt4.htm
http://www.lt1intake.com/files/faq.html
-- Joe
Racer
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Originally Posted by teufelhund
I was told that these heads would give me a slightly higher compression over my iron heads and probably give me a few pones like possibly 5-10.
Originally Posted by teufelhund
Also one last thing how hard would it be to just pull my old heads off and drop these in? Should I just go ahead and have them replace the timing chain as well? I know I'm going to be getting all new gaskets and the timing will need to be redone but other than that will the pushrods just stay in place so I can just pull the old heads off and drop these on??
Racer
Joined: May 2006
Posts: 293
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Originally Posted by anesthes
Are you sure? Both the 128 heads that came out of my car when I sold them, and the 113 heads in my cousin's '90 had the center bolts almost straight up. And I could have sworn the last singleplane manifold I made for my buddy's GTA/113 head setup had to be slotted to bolt up. (was a holley street dominator intake converted to efi). hrmmm..
Originally Posted by anesthes
Well, according to John prior to him selling lt1intake.com, the LT4 manifold is way different. According to the specs in this link, it appears
the ports are slightly different. (which is not way different). so who knows. *I* have never touched one.
I do know, when summit was selling the LT4 intakes, they also sold the LT4 heads - so I don't know if they were needed or not.
http://www.grandsportregistry.com/lt1vslt4.htm
http://www.lt1intake.com/files/faq.html
-- Joe
the ports are slightly different. (which is not way different). so who knows. *I* have never touched one.
I do know, when summit was selling the LT4 intakes, they also sold the LT4 heads - so I don't know if they were needed or not.
http://www.grandsportregistry.com/lt1vslt4.htm
http://www.lt1intake.com/files/faq.html
-- Joe
Thread Starter
Racer
Joined: May 2006
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From: Urbana OH
Wouldn't this increase be the same increase that is given with the 86L????? Aren't these the exact same heads they used on the 86 convertables???? And if I get a bump of a full point I'm still at 10.5:1 which isn't over the top by any means. What would I need to do to make it work. With new gaskets is this a weekend job that can be done by your average guys or is there anything special I need to know that than timing problems.
Thanks for all the help guys.
Racer
Joined: May 2006
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Originally Posted by teufelhund
Wouldn't this increase be the same increase that is given with the 86L????? Aren't these the exact same heads they used on the 86 convertables????
Originally Posted by teufelhund
With new gaskets is this a weekend job that can be done by your average guys or is there anything special I need to know that than timing problems.
Drifting
Joined: Mar 2002
Posts: 1,251
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From: Thomson Georgia
Gee, didn't know the GTA was a Corvette.
The CORVETTE heads from a CORVETTE have the same bolt pattern as a pre 1987 SBC head.
NON CORVETTE heads, aka truck, camaro, Z28 and others did change after 86 to a different angle on the 2 pairs of bolts around the crossover passage.
You do not need to slot these bolt holes on the intake if it is a corvette head. Unless you put a non corvette TPI intake, aka Camaro, Z28.
Most of the intakes made today have the slotted bolt holes and you should use a good flatwasher on these bolts to have good clamping from the bolts.
Compression wise, usually 10-12 cc will change the compression 1 point. 1 point higher in compression is generally good for around 3% horsepower increase, crankshaft.
Going to 1.6 RRs, with the 113s, should net you around 20-25 HP increase.
You still should not have a problem with a .041 head gasket, attention to static timing and good gasoline.
The 113 heads have changes which are beneficial to power.
LT1s are a different bear altogether, although they will bolt on a L98, you will have serious cooling problems and no way to hook up a t'stat and return hose without MAJOR mods to both the LT! heads and intake.
The CORVETTE heads from a CORVETTE have the same bolt pattern as a pre 1987 SBC head.
NON CORVETTE heads, aka truck, camaro, Z28 and others did change after 86 to a different angle on the 2 pairs of bolts around the crossover passage.
You do not need to slot these bolt holes on the intake if it is a corvette head. Unless you put a non corvette TPI intake, aka Camaro, Z28.
Most of the intakes made today have the slotted bolt holes and you should use a good flatwasher on these bolts to have good clamping from the bolts.
Compression wise, usually 10-12 cc will change the compression 1 point. 1 point higher in compression is generally good for around 3% horsepower increase, crankshaft.
Going to 1.6 RRs, with the 113s, should net you around 20-25 HP increase.
You still should not have a problem with a .041 head gasket, attention to static timing and good gasoline.
The 113 heads have changes which are beneficial to power.
LT1s are a different bear altogether, although they will bolt on a L98, you will have serious cooling problems and no way to hook up a t'stat and return hose without MAJOR mods to both the LT! heads and intake.
Last edited by johnnyevans; Feb 14, 2007 at 07:09 PM.
Racer
Joined: May 2006
Posts: 293
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Originally Posted by johnnyevans
Gee, didn't know the GTA was a Corvette.
The CORVETTE heads from a CORVETTE have the same bolt pattern as a pre 1987 SBC head.
NON CORVETTE heads, aka truck, camaro, Z28 and others did change after 86 to a different angle on the 2 pairs of bolts around the crossover passage.
You do not need to slot these bolt holes on the intake if it is a corvette head. Unless you put a non corvette TPI intake, aka Camaro, Z28.
Most of the intakes made today have the slotted bolt holes and you should use a good flatwasher on these bolts to have good clamping from the bolts.
The CORVETTE heads from a CORVETTE have the same bolt pattern as a pre 1987 SBC head.
NON CORVETTE heads, aka truck, camaro, Z28 and others did change after 86 to a different angle on the 2 pairs of bolts around the crossover passage.
You do not need to slot these bolt holes on the intake if it is a corvette head. Unless you put a non corvette TPI intake, aka Camaro, Z28.
Most of the intakes made today have the slotted bolt holes and you should use a good flatwasher on these bolts to have good clamping from the bolts.
EGGSACTLY!!! I think that is what I said, above, several times.
Originally Posted by johnnyevans
Compression wise, usually 10-12 cc will change the compression 1 point. 1 point higher in compression is generally good for around 3% horsepower increase, crankshaft.
Originally Posted by johnnyevans
LT1s are a different bear altogether, although they will bolt on a L98, you will have serious cooling problems and no way to hook up a t'stat and return hose without MAJOR mods to both the LT! heads and intake.