Never in my life have I had such poor luck getting a seal on the rear of the intake. I have re-done it 3 nights in a row and still have a leak! (I am getting good at pulling the intake in 10 minutes or less!) So far I have tried: 1) No cork seals just a 3/8 bead of Blue and letting it get slightly firm = LEAKS 2) Cork seals with 3/8 bead of blue on both sides, letting it get tacky = LEAKS 3) Tried #2 above and let it set for 24 hrs = LEAKS! Any ideas ? This is getting frustrating. I am also having a similar issue with one valve cover. And yes, I have tried a new tube of blue to make sure it was not the issue. I think I am the issue!
Only thing I do different is not letting the silicone get tacky. Do the silicone last and on goes the intake. Not something silly like to much crankcase pressure? PCV system is OK? Also silicone shouldnt be used on seals like the intake end seals and rocker gaskets, especially cork. It has a bad habit of making the seal pop out. Use the seal or use silicone as a seal replacement.
Question, how do you know you have a leak? What's it doing? When I replaced my gaskets and cork seals, I cleaned all surfaces with alcohol (after cleaning to removed all gasket material) and put a bead of RTV on block for cork seals only, then placed seals, then another bead of RTv on top of seals. I then placed my intake on top and made sure the seals remained aligned with the edge of the intake...front and back edges. I then installed each intake screw and just hand tighten them in order as recommended. I checked seal alignment after one more time, prayed, and let it dry for a few hours. After a few, I came back, checked alignment, they were still aligned, and torqued them down as recommended. All looks good. When I did this before, the seals were sliding out of position when I was torquing them down. It was a pain, had to do this twice. Good luck.
I had to take my intake off to do some work to it so I had to buy a new set because it was on there for awhile. When I completed the intake job and reinstalled it and later found the cork seal issue, I had to buy another gasket set to use the corks but reused my intakes. All okay.
I've used both the silicone and the cork seals. But i just use one or the other. If I use the cork i just put a dab of silicone in the corners.
I use cork. Don't use silicone on the cork. When you use the end gaskets, you just put a dot of silicone right in the corner where the cork and the port gaskets all meet. Put the cork on the engine like this, make sure it doesn't want to move, then place the intake down square as you can. If you adjust the positioning of the intake vs block after the intake is too close or touching gaskets, it will shift them. STRAIGHT DOWN is the important thing. If you don't want to use cork, that's when you need a bead of silicone. In which case I use the black (or red), high heat stuff. I don't like the blue for anything on the engine/tranny/rear end. They get too hot for the light duty stuff in my experience.
I will try cork tonight with just silicone on the corners. Thanks all.. Same concept on the valve covers ? Like I said, I have done this a 100 x's for some reason this week is not working for me! (Likely because of a car show deadline!)
I have always just used the red RTV and let it skim over about 30 minutes. Let it dry over night after I torque it down. Another thing to help on a 302 is to use some cut off bolts as guide studs so when you lower the intake you don't smear the RTV. Have your heads been shaved a lot? Is it a used intake that might have been machined to fit some shaved heads? Like said about, too much crankcase pressure? Is your dip-stick popping up on you or anything like that? Either use the end gaskets or RTV but not both except at the corners. If you use a gasket take a center punch and make a few dimples across the top of the block to help hold the gaskets clint
Valve covers are like any other sheet metal cover or pan for you drivetrain. Over time they dimple down around the bolt holes. You have to hammer out the dimples and make the surface flat again. Then be sure not to overtighten, or you will bring the dimple right back to the flange. Dimples keep the gasket tight right there at the bolt, but they allow the rest of the flange to gap and hold the gasket unevenly. Pounding out the dimples works great on oil pans and tranny pans as well.
If you use the cork end gaskets...glue them to the block with gasket shellac(gaskacinch)black goo stuff...Or some 3M weatherstrip adhesive.Let it set up for a bit,then put a dollop of RTV in the corners and place the intake on the engine and torque it down.Rocker covers can be a PITA.I like to glue the gaskets to the head with aerosol contact cement...(no I spray it on the gaskets head side only)put the gasket in place...let it set up then place the covers on after straightening the rails and "snug the cover bolts" Dont gorilla them...
