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these photos probably aren't particularly helpful but I'm trying to show that the throttle blades are completely closed and there's still a fair bit of space for the linkage to go
while taking these photos and trying to find a part number on the intake manifold i noticed water pooled on the Bell housing. so apparently I'm having that same leak again. I'm starting to wonder if this manifold is cracked. any recommendations for gaskets? the fel pro ones I've been using are clearly not up to the job
When you take it apart again, I would clean everything up and then sit the intake on the engine dry with no gaskets. See what it looks like, and if it matches up to the angle on the heads. Sometimes people will surface the heads and deck the block, and it throws everything off and they have to mill the intake to match up. Of course then, the intake will not fit most other engines. If that is the case, this intake has probably been passed around on marketplace many times. If you find your intake hits the china wall before it hits the head surface, you can probably take it and get it milled some in the middle to help it seal.
I see also Summit racing and others sell thicker intake gaskets, up to .090 thick. Felpro part number 1262 R4
Last edited by Franklin2; Oct 14, 2025 at 07:40 AM.
The difference between the 1262R2, R3 and the R4 is the thickness of the gasket. The 1262R2 is .045" thick, The 1262R3 is .060" thick and the 1262R4 is .090" thick.
When you take it apart again, I would clean everything up and then sit the intake on the engine dry with no gaskets. See what it looks like, and if it matches up to the angle on the heads. Sometimes people will surface the heads and deck the block, and it throws everything off and they have to mill the intake to match up. Of course then, the intake will not fit most other engines. If that is the case, this intake has probably been passed around on marketplace many times. If you find your intake hits the china wall before it hits the head surface, you can probably take it and get it milled some in the middle to help it seal.
I see also Summit racing and others sell thicker intake gaskets, up to .090 thick. Felpro part number 1262 R4
When ever I am installing a intake that has not been on that motor combo before this is just what I do, lay the manifold on the motor without gaskets and check how the fit is between the manifold and heads and how thick a bead of RTV to make for the front & rear gaskets to replace them rubber ones as I dont use them.
On the motors I mess with this is vary important as they use a metal pan gasket with just spray tack to seal the manifold to heads and if the angle is off you will get a leak, if lucky, or crack the manifold.
If I did not use the pan gasket hot oil hits the bottom of the manifold and heats it up so you want to use the pan gasket in my case.
As a test pull the PCV and plug it and see if the idle comes down. The manifold could be leaking from the valley side. Have you seen the motor use more oil?
I really think you have a vacuum leak. Oh I like to test for a leak with a rag or my hand over the carb chocking it off, snaek up on it when doing this.
If it wants to stall out right away no leak if it runs better you got a leak. Pretty simple
Dave ----
Most all engines idle will slow when plugging the PCV valve. The PCV valve is a calibrated on purpose vacuum leak. Now if it's the wrong PCV valve for that engine, it can cause some problems.
Most all engines idle will slow when plugging the PCV valve. The PCV valve is a calibrated on purpose vacuum leak. Now if it's the wrong PCV valve for that engine, it can cause some problems.
But if the intake was not sealing at the valve valley side it could cause a vacuum leak the PCV was coving.
I have not see that much of a change in RPM with the PCV installed or pulled and plugged but has been a while since I done it.
Dave ----
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