How can I get this to seal?

[travis]

Is there such a thing as gasoline proof RTV?

This is on a 1987 iron 351w intake. The EGR port was plugged years ago with high temp epoxy and it has held up well. The old EGR plate and the mounting surface of the intake are pretty badly eroded from EGR. I got it to seal years ago but the seal finally failed, creating a vacuum leak. I can't for the life of me remember what I did to get these pieces to seal up years ago.
I've given up on the EGR plate. I'm using a 1" thick open spacer simply for dual feed fuel line and linkage clearance with an 80670 Holley. I've tried 3 times over the last couple weeks to get it to seal and I'm still getting a small vacuum leak on the passenger side. Current setup is a 1/4" thick insulation gasket on the manifold, then spacer, then a regular carb gasket.

IMG_20240405_164625_132.jpg

The stock intake works great with this very mild 351w. I just need it to work for a few more months.

[hoodeng]

Probably not what you want to hear, take the manifold of and give the surface a lick in the mill. An afternoon's work.

[F-BIRD'88]

Check the carb flange for flatness first.

[clay]

“Is there such a thing as gasoline proof RTV?”

Give this a try. I’ve only used it on 2 stroke crankcase halves so far but think it might be what you’re looking for. Clay


https://www.permatex.com/products/gaske ... ey-2-7-oz/

[1972ho]

Home Depot sell a 6 inch long rectangular grinding stone that will fit across the flange and then get yourself a tube of the valve lapping compound and then run a few passes across the flange in a figure 8 type motion and then you will be able to see if the surface is flat and square.

[travis]

The carb base is flat. The manifold flange is flat except for that eroded area on the left side.

I'm going to try the $10 solution first (RTV). If that doesn't work, then off to the machine shop.

Thanks for the suggestions.

[BillK]

The carb base is flat. The manifold flange is flat except for that eroded area on the left side.

I'm going to try the $10 solution first (RTV).

Personally I would use JB Weld or some other epoxy. Put on a thin layer with a plastic spatula and let it set up then use a nice flat file and go over it.

The other thing is some of the thick base gaskets have plastic grommets at the bolt holes that really do not allow them to compress very much. I would just go with a regular gasket.

[engineman1642]

That port goes to exhaust. Never had much luck with silicon or epoxy. Last one i did i used the EGR plate,milled off the mount on the back and plugged the two holes with pipe plugs.

[travis]

That port goes to exhaust. Never had much luck with silicon or epoxy. Last one i did i used the EGR plate,milled off the mount on the back and plugged the two holes with pipe plugs.

I used iirc JB Weld hi-temp epoxy. Cleaned out the port with a Dremel as far down as I could reach, packed it up with the epoxy, and let it set up a day or 2. It's been in place for 3-4 years now

[dgeman79]

It's a little on the expensive side but devcon epoxy holds up to heat very well.

[rebelrouser]

I know a lot of guys that use high temp orange silicone for header gaskets and it seems to hold up well, I would think it would work just as well for your issue.

[RCJ]

Where are you located I'm in Oklahoma. I threw a 4 barrel 351w intake in my junk pile last week. I'll look at it tonight

[travis]

Where are you located I'm in Oklahoma. I threw a 4 barrel 351w intake in my junk pile last week. I'll look at it tonight

I work in Tulsa, live about 45 minutes east

[RCJ]

I work by Mingo and Pine get off at 4:00. I got it in the truck it ,looked oK not corroded.

[winr]

Autolite 4100 carb will not seal on a Edelbrock Performer 390 FE intake intake

I bought a 1" high 4 hole spacer, solid on both sides ( drilled and tapped the spacer for a 3/8" brass nipple for PCV hose )

The solid spacer might work ( I have a thick piece of glass I glue large sheets of sandpaper on too and hand mill things )


Ricky.