351w (5.8L) Intake install - RTV or Cork Gaskets on front and rear "China Wall"
 

When re-installing the factory intake manifold on a 351w (5.8L), do y'all like to use the cork (or rubber) gaskets for the front and rear "China Wall" or do you prefer to use RTV only in these areas like Edelbrock recommends when installing their intake manifolds?

I like the idea of the rubber gaskets but in practice I found they didn't stay put and would begin to squirt out after only a year or so. The best sealing solution I found was to glue the cork gaskets to the block with contact cement and then put RTV in the corners and across the top to seal against the intake. This lasted about a decade on the 351 I built for my 'F150.

I had rubber on one engine, cork on the another, both leaked oil. My recent build was RTV only, no leaks thus far (about two years). I'd do RTV again.

Instructions for cork gasket to work properly:

"carefully remove cork gasket from package. Place immediately in the trash can."

I made 4 long studs for the corners of the manifold.

Laid down a clean, thick, solid bead of Permetex blue without the nozzle.

Barely touching the intake gaskets at the ends of the "walls".

Let it sit for 10 minuets to "skin" & drop the manifold straight down.

Let sit for additional 10 minuets with just the weight of the manifold. pressing down.

Tighten in circular pattern center bolts out just "snug".

Then torque with wrench to spec.

Best seal I ever had. Absolutely no weep or leak.

Thanks. This is the approach I've always taken when installing aftermarket intakes on small block Fords (with good success), but I didn't know if there was some reason not to do it on the factory intake.

Agreed 200%

In my schooling we had a "customers" car come in with an intake leak. My friend and I were "volunteered" to do the job. Just as we were getting ready to set the intake on out "instructor" stopped us and ripped us a new one for using RTV in the front and back of the intake. He made us pull the rubbers out of the garbage and use them. A week later the car was back with a leak from the rubbers. The instructor insisted we installed them incorrectly. So we let him install them the second time. A week later the car came back again. This time me and my friend quickly got it DONE before the instructor came around and we disposed of the rubbers. A week later he had the customer bring the car back to check on it. He was all proud that there were no leaks, so we showed him the rubbers :-X06