Maybe, coat the intake or head port side with engineering blue to determine where the suspect leak is located?
This is, of course, you are following best practices with sealing the front and real rails and can rule these locations out?

 

I have heard a discussion from a Mopar guy on this because a lot or maybe even most of the old Mopars ran valley pans. I have a 351C fresh on the engine stand too so I tend to try and gather as much info as I can related to this particular engine since I'm going to build out this thing. The Mopar dude was complaining as he tore down an engine because he found the metal valley pan and no paper gasket with it. The person that did that just put down silicone and smashed the intake down on top of it and he didn't think that was a very good idea. I don't think you are supposed to reuse the ends either. I have no experience yet with making on of these seal up so I don't know from experience.

 

I had to look up what engineering blue was but that seems like a great idea!

Its been a few years since I have had the intake off, (car sat from 2006-2018) but I assume I am following best practices installing the intake. I toss out the included cork ends for the china wall and use RTV, but recently picked up a tube of The Right Stuff to use next time I pull it off. Current gasket is a Fel Pro 1240, but thought I might try the turkey pan with the Edelbrock to see if I had any better luck.

 

I will share my experience with my 351C 2V::

- Whenever I have tried to use typical "thick paper" gaskets with an Edelbrock Performer intake, the gap at the front and rear were very large. The thick paper gaskets made the intake sit too high and it was extremely difficult to lay down a large enough bead of sealer to fill this gap. I would consistently get oil leaks at the back of the intake. I have seen some people use a combination of the cork gaskets and a bead of sealer in this situation, but I have not tried that.

- Also, when I tried to use thick paper intake gaskets with the Edelbrock Performer intake, I would repeatedly get vacuum leaks. No amount of proper torquing and re-torquing would solve the problem.

- I eventually went with a Felpro "Turkey Pan" gasket set and that worked. I would suggest spraying both sides of the port areas of the metal gasket with Permatex "Copper Coat". That stuff provides a thin, tacky surface that seals very well, is impervious to heat and comes off easily with no gooey residue. I've done this with the intake gasket and it worked very well. I got this idea from seeing people install metal head gaskets with Copper Coat. I figured if it sealed a head gasket, an intake gasket should be no trouble. Seems I was correct.

- The Felpro Turkey Pan gasket comes with neoprene ("rubber") seals for the front and rear and a tiny tube of RTV black. You're supposed to lay down the neoprene seals and apply a small bead of RTV at the ends to help seal the transition at the corners.

BTW, the 351 Cleveland is very different from other V8 engines. It has a dry intake and what works for a 302 or 351W, for example, doesn't really apply to a Cleveland

 

I will share my experience with my 351C 2V::

- I eventually went with a Felpro "Turkey Pan" gasket set and that worked. I would suggest spraying both sides of the port areas of the metal gasket with Permatex "Copper Coat". That stuff provides a thin, tacky surface that seals very well, is impervious to heat and comes off easily with no gooey residue. I've done this with the intake gasket and it worked very well. I got this idea from seeing people install metal head gaskets with Copper Coat. I figured if it sealed a head gasket, an intake gasket should be no trouble. Seems I was correct.

- The Felpro Turkey Pan gasket comes with neoprene ("rubber") seals for the front and rear and a tiny tube of RTV black. You're supposed to lay down the neoprene seals and apply a small bead of RTV at the ends to help seal the transition at the corners.

Should I use the gaskets (not the China wall gaskets, but the additional intake to head gaskets) that came with the turkey pan as well, or just spray both sides of the turkey pan ports with Permatex?

 

Thank you Klutch! Sounds like we have had similar vacuum issues with the Performer, you give me hope! I'm glad I ordered the Felpro turkey pan after all!

Hopefully ill get a chance to pull the 2bbl off this weekend and try the Edelbrock again. While I am thinking about it, I better pick up a carb rebuild kit for my Carter before throwing it back on.

Thanks again!

BTW - I read through your 17 page build a few months ago and needless to say the work you have done is down right impressive. I could only dream of my 70 being as nice as yours. Well done sir.

 

70, on 351C small ports, I like the 1240 with RTV. Lots of aluminum intakes don't seem to like the turkey pans, but I will agree the copper coat is great stuff, and you could try it. If your stock iron intake fitss well, you can almost guarantee yourself that you have a warpage problem, not a milled problem. LSG

 

A little update for anyone who might care:

Finally had a chance to track down the performer intake buried in the garage to have a fresh look at it. I took a straight edge to the ports and got a flashlight to shine behind it. Lo and behold, I could see light coming through at various spots along the ports. Looks like the intake is in fact warped. Don't know why I never thought of checking it like this before...

Good news is, I went ahead and ordered the RPM Air Gap manifold to replace it.

Bad news is, it is backordered until next month, and now the Summit 600cfm carb is also out of stock for another week or so, but that's alright. My new gas tank and fuel lines should be here this week which will keep me busy for a little while.


Question: I'm leaning towards ordering another Felpro turkey pan for the new intake but also thinking of trying a Felpro 1240. Decisions decisions...

Also trying to figure out if I will be able to use any sort of a carb spacer with this higher sitting manifold. Guess Ill have to wait and see how much room I have with my current setup before ordering anything new.