'68 390 Mods

67 Marlin wrote: Why is the baffle so big? Why does it need to cover the entire center part of the intake? If it's just a PCV baffle, then isn't the only part that's really needed the quarter section in the upper left-hand of the photos, where the PCV valve is? Could someone just fab up a piece of sheet metal in that one place and meet the need?

My guess would be that, since the center ports in the intake handle hot exhaust gases, the center portion is to keep motor oil from direct contact with that heat and "coking up" the bottom of the intake with burnt motor oil.

But that's simply my guess.

If you get a chance read my post 69 390 using oil low vacuum it is a recent post you're talking about my saying problem I'm down to trying to find out if the intake pan is a gasket or do I need a second set of gaskets with the intake pan and where the best places to buy them. As far as my vacuum problem I'm thinking it's the cam plus the line running to the brakes vacuum canister was brittle where it was bolted to my intake I think I have everything solved now just trying to get parts to put back together

What I'm trying to figure out is the Valley Pan the pan and the gasket in one. Or do I need the separate gaskets and the Valley Pan I saw one post where they just put the Valley Pan in. I'll be interested in seeing how you make out.

Just talking...

Edited by PHAT69AMX - Apr/23/2018 at 8:34pm

I see you pulled it. That gasket was leaking so good job. I install several of these a week. Here's some tips.

Use a large bead of Right Stuff instead of end seals.

Never, ever, ever, Use silicone RTV Around the intake ports, none are gas proof. Use Permatex #2 Or aviation form a gasket.

Right Stuff or RTV around the water ports. Do both sides of the gasket.

Seal all bolt hole beads in the gasket with AV Forma a gasket also to prevent oil weeps onto the intake surface, ugly.

A 3/8" tall bead of Right Stuff is good front and rear rail. Also a strip from the corner of the water jacket to the end rail.

Set the manifold on accurately, don't slide it to align it.

Put the bolts in just snug, not tight and walk away for twelve or so hours to let the sealers set up. After you let it sit for the day, tighten to specs. This allows the sealers to form a chemical bond and harden in place. When you tighten it the rest of the way it compresses the newly formed end seals and gives a strong mechanical bond also. You will have no leaks ever.

PCV must never be pulled from an intake runner. It must always be pulled from the common plenum area. If you pull PCV from a runner fitting, it will severely lean that cylinder and cause oil fouling also. The PCV flow must be shared with all cylinders. The carb fitting or base plate is the correct place to pull PCV. Port fittings are for dead head vacuum only like gauges or vacuum actuated vent/ ac ducting. Vacuum wipers are flow through systems and should be pulled from the carb also.