ISO - I am looking for a LT-4 Intake manifold.
Need one for my 1997 5.7L 350
GM Part Numbers
12550630 12550631
Edelbrock 7109
Not sure of any other options.
These are generally powder coated Red.
The LT1 manifold will not work on the LT4 Heads

Recently purchased a 1997 LT engine with out the intake. Not knowing it has LT4 heads and needs an LT4 intake manifold.
New to the LT world.

Please PM me if you have one and what you would want. I am located near Hershey, Pa in the 17078 Zip Code

Thank you.

 

To be really useful with LT4 heads, the LT4 intake manifold needs to be ported. Huh? GM took the LT1 casting, added some more metal at the top of the LT1 runners. While the metal is there, GM never got around to raising the top of the intake manifold ports to match the LT4 head ports.

This info came from Pete Incuado at CNC Cylinder Heads in Pinellas Park, FL. He claimed to have participated with GM in the development of the LT4 heads. When GM realized there was no use for the LT4 heads in the Corvette after 1996, they stopped the development program to save $$. Basically, the ports/runners on the LT4 intake manifold are the same configuration as the LT1 intake.

Back in 1999 I had picked up an LT4 intake from a buddy of mine. I ordered a set of bare LT4 heads through CNC Cylinder heads. Pete told me to send him the intake so he could port that, as well as the heads. He told me to flow the head with the intake manifold bolted on. The shop that was building my 381ci engine flowed the head alone and got a peak flow of 290 CFM, good compared to what was available in 1999. They bolted on the intake and retested. Picked up a shade under 3% additional flow, just under 300 CFM. This page indicates the factory LT4 heads flowed 240 CFM @ 28”:

https://www.grandsportregistry.com/lt1vslt4.htm

https://www.camaroz28.com/g/picture/13793481

I would be hesitant to run the Edelbrock intake. Tests from 20+ years ago showed the LT1 version plenum lost a bit of volume due to raising the plenum floor to provide the “air gap” feature. The loss of volume was shown to hurt high RPM/high flow demand HP.

 

Great info, Much appreciated. I would prefer the OEM, but if none to be had I would settle for the LT4 Air Gap.
.
If I can't locate one, I will be pulling the LT4 heads and selling them. Then go with 1996 LT1 Aluminum Heads. Anyone have an idea what the LT-4 heads are worth these days?


Was told they came out of a 77K 97 Trans Am. Previous owner couldn't get it running and sold intake.
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Great info, Much appreciated. I prefer the OEM Intake, but if none to be had I would settle for the LT4 Air Gap.
.
If I can't locate one, I will be pulling the LT4 heads and selling them. Then go with 1996 LT1 Aluminum Heads. Anyone have an idea what the LT-4 heads are worth these days?


Was told they came out of a 77K 97 Trans Am. Previous owner couldn't get it running and sold intake.
​​​​

 

Call Lloyd Elliott and see what he would give you for the LT4’s, if interested:

http://elliottsportworks.com/

Tab at top for Contact info.