LT4 Intake Gasket Confusion?
Thread Starter
Racer
Joined: Jul 2022
Posts: 495
Likes: 163
From: Wilmington,Delaware
Getting off topic, but some of the early press releases for Grand Sport was 52 mm throttle body. Rumor was the LT4 was making too much horsepower compared to the plans for the upcoming LS engines. Going back to 48 mm was one of the steps GM took to reduce the horsepower.
Again off topic, but I port matched my intake to a 58 mm throttle body.
To the original poster I think you have got your answer regarding suitable intake gaskets.
Again off topic, but I port matched my intake to a 58 mm throttle body.
To the original poster I think you have got your answer regarding suitable intake gaskets.
Drifting
Joined: Apr 2000
Posts: 1,390
Likes: 36
From: INDIANA
Just ran across this thread. I installed LT4 heads on my 92 back in 96 when they came out. I bought all the parts at the local GM dealer and they shipped intake gaskets that were not right. Seems like 12528884 part number but they had the ports taller on the bottom end, not the top. I worked for GM and contacted an engineer in Detroit and he did some research and someone had reversed the prints and made the gaskets wrong. The correct gasket was then given the part number 12367777 and the matched the ports on the head correctly. I never did get an answer why the LT4 intake was not designed with ports to match the heads, but they did add the material for it to be done in the field.
Crazy things happen when things are one off for 1 model year.
Crazy things happen when things are one off for 1 model year.
