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install 1990 engine into 1976 corvette

 
Old 05-13-2019, 03:03 PM
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Myoldvette76
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Default install 1990 engine into 1976 corvette

Can anyone help?
I am installing a 1990 L98 engine into my 1976 corvette. the clutch in the 76 is a push style and the 1990 is a pull hydraulic style.
Is there a 11 inch push style clutch that would fit on the flywheel so i can use my existing clutch pedal and rods?
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Old 05-13-2019, 03:44 PM
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Welcome to the CF! Try posting your question in the C3 area of the forum.
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Old 05-13-2019, 04:43 PM
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Moved over to C3 Tech.
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Old 05-13-2019, 07:27 PM
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jackson
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We already Know 76 flywheel does Not fit 90 crankshaft.

? What size is 76 flywheel? 153 Teeth or 168 Teeth?

? Do you have 90 flywheel?

? What size is 90 flywheel? 153 Teeth or 168 Teeth?

? Will you use 76 bellhousing or 90 bellhousing?
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Old 05-14-2019, 08:48 PM
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you may need a conversion flywheel which are plentiful
your block uses a 2 pc rear main the 90 a 1,

Last edited by cuisinartvette; 05-14-2019 at 08:48 PM.
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Old 05-15-2019, 08:12 AM
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Why not use the hydraulics of the 90 and just get a conversion to eliminate the clutch rods. Seems like less work and better results to me.
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Old 05-15-2019, 10:22 AM
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The 1990 L98 Engine is already a one piece rear seal. It is basically the same exact block, with the exception of the provisions for the one piece crank (aluminum casting to hold viton seal) and the only difference with the flywheel on the L98 engine is that it does incorporate an offset weight to counter the loss of the flange on the two piece crank. The manual trans bell housing for the '68-'76 is a direct bolt on, with the only modification needed is to the early flywheel inspection cover to cut a bit off the upper edge. I just did this exact swap using the '87-'91 roller lifter block (which the L98 was). Hope you're keeping the serpentine belt drive off the L98. The only thing you'll have to do is reclock the power steering outlet and make sure you're running the L98 water pump (reverse rotation, because of the belt routing). Of course, pay attention to the flywheel diameter and the tooth count for starter compatibility but any early clutch and pressure plate will fit. As far as flywheels, you must use the one piece flywheel, because it has a smaller bolt hole diameter.

Original '74 engine with the original four speed bellhousing attached.




Original '74 Bellhousing is a direct bolt on to any '87-'91 roller lifter 350 block as shown below. Worked exactly the same. Note the casting number on the '87-'91 block below. That's commonly known as a 638 block.




Flywheel Inspection Cover Mod below. Check your old one first to see if there's actually an interference fit. Mine wouldn't go in and had to cut away the upper edge as shown below.


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Old 05-15-2019, 10:57 AM
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Kacyc3
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Originally Posted by F22 View Post
The 1990 L98 Engine is already a one piece rear seal. It is basically the same exact block, with the exception of the provisions for the one piece crank (aluminum casting to hold viton seal) and the only difference with the flywheel on the L98 engine is that it does incorporate an offset weight to counter the loss of the flange on the two piece crank. The manual trans bell housing for the '68-'76 is a direct bolt on, with the only modification needed is to the early flywheel inspection cover to cut a bit off the upper edge. I just did this exact swap using the '87-'91 roller lifter block (which the L98 was). Hope you're keeping the serpentine belt drive off the L98. The only thing you'll have to do is reclock the power steering outlet and make sure you're running the L98 water pump (reverse rotation, because of the belt routing). Of course, pay attention to the flywheel diameter and the tooth count for starter compatibility but any early clutch and pressure plate will fit. As far as flywheels, you must use the one piece flywheel, because it has a smaller bolt hole diameter.

Original '74 engine with the original four speed bellhousing attached.




Original '74 Bellhousing is a direct bolt on to any '87-'91 roller lifter 350 block as shown below. Worked exactly the same. Note the casting number on the '87-'91 block below. That's commonly known as a 638 block.




Flywheel Inspection Cover Mod below. Check your old one first to see if there's actually an interference fit. Mine wouldn't go in and had to cut away the upper edge as shown below.


I think he is trying to use the newer trans also and why he was asking about converting from the push to pull clutch.
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Old 05-15-2019, 11:39 AM
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KacyC3, I don't know. He didn't specify, exactly which transmission he was using. The Doug Nash Overdrive, or the original Muncie or Borg Warner? Maybe he'll chime in and tell us, which is which, because that would make a huge difference!
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Old 05-15-2019, 11:42 AM
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There is another thread with same questions.
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Old 05-15-2019, 12:00 PM
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Originally Posted by derekderek View Post
There is another thread with same questions.
Link?
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Old Today, 08:27 AM
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Myoldvette76
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Default 1990 install

Hey guys. Thanks for all your help and suggestions on my clutch issues. Finally got the right clutch.thanks to the person who sent me the link .my next problem is that is the exhaust manifold on the passenger side. One of the flange bolts is being blocked by the idler arm. Is there some way of offsetting the idler arm away to get access to install the pipe.
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Old Today, 08:37 AM
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dmaxx3500
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use the hyd clutch set-up

you can buy the master cyl for a ''s-10 or camaro'',that's how we did the Datsun/gto conversions 20+ years ago
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Old Today, 08:46 AM
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jackson
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Originally Posted by Myoldvette76 View Post
Hey guys. Thanks for all your help and suggestions on my clutch issues. Finally got the right clutch.thanks to the person who sent me the link .my next problem is that is the exhaust manifold on the passenger side. One of the flange bolts is being blocked by the idler arm. Is there some way of offsetting the idler arm away to get access to install the pipe.
did you end up with this clutch kit?

https://www.summitracing.com/parts/sum-700812/overview/
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Old Today, 08:53 AM
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Myoldvette76
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Default 1990 install

Yes. It fit perfectly.
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Old Today, 09:11 AM
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derekderek
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Originally Posted by Myoldvette76 View Post
Hey guys. Thanks for all your help and suggestions on my clutch issues. Finally got the right clutch.thanks to the person who sent me the link .my next problem is that is the exhaust manifold on the passenger side. One of the flange bolts is being blocked by the idler arm. Is there some way of offsetting the idler arm away to get access to install the pipe.
Use the Corvette exhaust manifolds. You don't want to be having a custom exh system fabbed to fit different manifolds and steering gets mad when you try to move it.
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Old Today, 09:46 AM
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Kacyc3
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Originally Posted by derekderek View Post
Use the Corvette exhaust manifolds. You don't want to be having a custom exh system fabbed to fit different manifolds and steering gets mad when you try to move it.
The L98 heads use a D shaped exhaust port I believe and this can cause sealing issues with exhaust. Best way to check is to use the exhaust gaskets for the manifold and set into place, checking to make sure the gasket wont cover the exhaust port and still has material on the sealing surface. If not you may have to use headers.
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