I picked up a Felpro gasket set for my '82 yesterday and would appreciate some advice.

First, the plenum gasket under the CFI plate didn't come with instructions regarding sealant. I'm not familiar with this gasket material. Should it be installed dry? RTV? Something else?

Second, I'm attempting to renew the fuel/ignition system of this old Vette as much as is reasonably possible. I don't want to repair it piecemeal for the next five years, so I'm replacing a lot of parts at once. Fuel filter, fuel pump, pump relay, TPS, CTS, etc., etc. In this regard, should I also pull the intake manifold and replace the intake gaskets that came in the kit, just as a matter of routine maintenance?

Third, if I replace the intake manifold gaskets, what sealant would you recommend? 30 years ago I would have run a bead of 3M yellow weatherstripping cement on the heads and left the upper surfaces of the gaskets dry. I'm not sure that cement is still available at auto parts stores, but even if it is, maybe there's something better out there now.

Finally, I was surprised to see that the Felpro set didn't include end gaskets for the manifold. I hate the rubber strips, but cork gaskets always worked well for me. This set came with a small tube of black RTV and instructions that say to use it on the ends in place of a gasket. Is this common practice now? No gaskets at all on the ends? Anything special I should know before I seal the ends this way?

Thanks!

 

Why did you buy the gasket set? If the side or end gaskets aren't leaking there's no reason to lift the manifold. The lid gasket is actually self-sealing as the powerful vacuum holds the lid down with such force it would be almost impossible to lift it up by hand as 200+ square inches of say 15" HG on it would be a considerable down force.

If you are determined to replace the gaskets definitely use the RTV to seal the ends because it'll provide a leak proof seal for the next 100,000 years (or more). I have always used 3M-8001 (yellow) or 3M-8008 (black) weatherstripping cement to glue the gaskets to the heads and RTV to seal the ends; making sure to put an extra dab onto the corners. Torque the manifold down to about 25 ft/lbs then use a putty knife to remove most of the excess off then use a gasoline soaked rag to remove the rest. The side gaskets should have come with stainless steel "block offs" to block the rear water jackets.

 

I'm thinking a 33-year-old intake gasket might not last much longer. Then there's the fact that all the plenum gaskets I found in a one-hour search came with the intake gaskets. The best price was at my local parts house, so that's what I bought.

So, when I pull the plenum plate, there won't be any old adhesive to scrape off? Just maybe remnants of the old gasket? That's good news!

Where have you been buying the 3M?

The Felpro set is blocked, but I think it's just the gasket material. I haven't seen metal block-offs in any of the online photos of this set.

 

I think it would be wise to do the intake manifold while you're at it. Ultra black RTV is the right 'stuff' to use for sealant. It is a silicone-based sealant...but it IS made for use with fuels/oils, where most silicones do poorly.

The '82 may have used a bead of sealant on the ends originally. But, even if it didn't, most new cars are built with robotically applied sealants, rather than gaskets, anyway.

But, when you apply it, you want to let it set up for 10-15 minutes before re-assembly of parts to it. That will allow the sealant to offer some resistance to the loads it experiences during re-assembly, so it will maintain a good seal. Set parts onto that soft sealant as carefully as you can. You may need a 'helper' for that task.

 

Plenty of YouTube videos on how to seal the intake to the block. The plenum needs to be cleaned and new gasket installed. The throttle bodies don't need to be removed as it's very rare the base gasket leaks. This will avoid resetting the linkage and balancing the TBs.
this would also be a good time to replace the EGR valve. Take your time, take a good amount of pics so you can get the wiring and some bolts are different. You'll have two or three bolts that have brackets and stuff that need to be put back. Also check the Plenum for flatness. I read that some have warped because of the heat from the EGR vent. Mine was fine but I guess it has happened. GM gooped the crap out of the plenum and all leaked at one time or another. I bought my car off my high school teacher and that was the first project we had on this car. It was 1984 and the car barely had 20,000 . The plenum was leaking and GM manual said to add more sealer without scraping off the old sealer. The GM tech did it twice under warrantee. The third time he had us do it in auto shop class. Felpro didn't make a gasket at that time so we had to clean and goop again. 20 years later, I bought the car and had to do it again with the felpro gasket.
It's easy, just keep track of your parts and dropping the manifold straight down is a must! If you get crossed up and it's not feeling right, take it off and start over.

 

replacing this gasket is normal for the crossfire.

 

I gotta replace my 82' intake gasket too. Would it be like replacing any other 350 intake gasket?

 

do you just need to replace the top gasket or the side gaskets too?most manifolds are one piece cross-fire has a top .454luvr has posted a pics of the gasket sides and the top.if you know how to do a normal chevy intake you can do a cross-fire.

 

I was just going to do the whole thing to be sure

 

Although replacing all the gaskets would be best, you don't have to if everything looks good. No oil or coolant leaks. You can just remove the top plenum bolts, clean the area of silicon and reinstall. The torque is fairly light on the plenum bolts. I think it was 25 ft lb. and use a crisscross torque sequence. If it cleans up well, I wouldn't use any silicon, just the gasket. You only need to remove the fuel line feed and return and keep the TBIs bolted to the plenum. Take pics of the throttle linkage, wires, cruise control cable and TV cable. Just to avoid any confusion if you walk away mid project. Good luck and it's a very easy project as long as you take your time.

 

you could check it . find the leak then fix what is needed.

 

I would go with anaerobic sealant. Harder to find but worth its weight in gold. Its sold under Permatex.

 

FWIW, I decided not to replace the intake manifold gaskets, just the plenum lid and TBI gaskets. Once I got in there, the plenum gasket had already been replaced with Felpro, and it didn't look very old. Wasted my time, but no way to know that with no history on the car.

 

As the vacuum holds the lid down with a lot of force the old gasket is more than enough as long as it's not damaged.

 

I would never put sealant on those gaskets, imho you will just "borrow trouble". They are designed to work pretty well dry. I've never had a problem installing gaskets dry.

 

I don't see how putting proper sealant on those gaskets is going to cause trouble...other than being more difficult to remove later. I've never seen one leak due to having [an appropriate type] sealant applied to it.

 

Yeah but the problem is it CAN (doesn't mean it WILL) work it's way into your engine. I HAVE seen that crap find it's way into carbs and clog up the ports. You just generally don't want to put anything in your motor that doesn't belong there. Murphy's law, if it can go wrong, it WILL.

 

If put on properly, it would never leave the sealing joint.

 

OK you guys...I AGREE With BOTH of you.

Excessive application so a sealant can cause internal engine damage if a piece of it breaks off. I have seen it....AND...in the same breath...I apply a thin layer to a gasket to aid it in sealing is something that I do quite often. SO....knowing 'when to say when' is important when applying the sealant to a gasket.

I can 'say' this. I have done NUMEROUS Cross-Fire intakes along with the Tuned Port intake plenum set-ups and I can HONESTLY tell you. DO NOT..at all cost use an air powered Scotch-brite scuff pad or anything like that to remove the gasket material from the gasket surfaces.....BECAUSE.....it actually can damage the aluminum surface and NOT seal when re-installed. I know people do it and have success in doing it...and I also know that some people do not know how to do it.

For those who doubt me...PM me with your phone number and I will call you when I get one in where someone did what I wrote NOT to do...and you can see for yourself the damage.

I normally take the Cross-Fire intakes off so I can verify that the top plate will seal correctly IF someone hacked at it with a scuff pad....BECAUSE ...they more than likely DID not re-install the top with using a torque wrench and proper torque and warped the top lid....which I have seen and had to correct......because...nothing is worse when the intake has a vacuum leak when you are trying to balance the throttle bodies or even get a Tuned Port running correctly and I can tell from my scanner that I have a vacuum leak.

DUB