Technical SBF-Use two cork gaskets or just RTV on intake manifold ends?

Dropping the intake on today on ‘62 260.
Not real familiar with the SBF’s, but it looks like the intake manifold end gaskets are a potential leak waiting to happen.
Do you guys use the gaskets or I’m thinking of running a 1/4” bead of gray Permatex instead.
Any preference?
Thanks!
Edit-Oh! What about ports around the water jackets? Felpro makes no mention of using any sealer on the intake gasket there. I figured a little more gray Permatex in the area might help?

 

I use the rubber gaskets supplied in the Felpro kit. One thing I like about the rubber gaskets is they have a lip that fits snugly over edges of the block and they also have dowels that fit inside holes in the block. Makes it tougher to dislodge the gaskets when installing the intake which is an issue on my 57 Ford because of clearance to the firewall. I place a small dab of sealer on each corner where the gaskets meet and that’s it.

As long as the mating surfaces are flat and clean you shouldn’t need anything around the water jackets.

 

I suspect you are likely to get a lot of replies to say use the end gaskets ............they must be good because that is what is supplied, they only leak if you are an idiot and install them incorrectly, silicon is rubbish etc.

BUT for me I have not had much success in maintaining a long term seal with the end gaskets (cork or rubber) so I use the gray Permatex every time with no issues. Just make sure you use a good bead and let it start to partially cure before you drop the manifold on.

 

I use silicone on the end rails. I know you are not supposed to, but I put a very thin smear of silicone around the water ports at the head ends and manifold.
Plus I super clean all surfaces with lacquer thinner first.
I don't have leaks or issues.

 

Some grades of silicone sealer are good to use for this. The silver or red Permatex RTV works well.

You probably know the SBF manifold hold-down bolts are threaded vertically into the head, unlike other makes of small blocks where the mountig bolts are normal to the head faces. That makes it possible to place a bead of sealer on each wall of the block, and using a couple/three pieces of 5/16 NC threaded rod lower the intake perfectly in place atop the sealer. Re torque the bolts occasionally.

 

Use "The Right Stuff" and guide studs as Frenchtown Flyer mentioned... no leaks!

 

Permatex Right Stuff is what I use never had one blow out on the Chevy's and other engines.

Back in the day I used to put center bunch marks in the China rail and the intake and use standard silicone like ultra blue .

 

Edelbrock tells you to use black RTV and not use the rubber strips. To each his own but i have good success with just black RTV. just let it set up for a day.

 

Everyone in the Foxbody community uses a bead off RTV. Nobody bothers with the cork or rubber end gaskets. Guys making 800 to 1000 hp....RTV

 

They have their intakes on and off more than the average driver no? I’d rather have something more permanent.

 

Tried that. Worked great. I was hoping my muscle head teenager would be here to help me drop it straight down on the engine, but he was gone. So I cut some drill rod.
Thanks guys.
Yeah, I just ran a bead on the ends and let it get tacky. I probably could have used a little less, but nothing a blade won’t fix. Put just a smidge of sealer around the water ports. (Valve cover for display only)

 

All of my Mustangs, my brothers SBF's, my friends small blocks, everyone I know tosses the china wall gaskets aside and lays down RTV. I've seen it fail one time. It was on one of my Mustangs for over decade without issue. And it was the standard at my Father's Ford dealership.

Your mileage may vary, but I in know what I will continue doing.

And yes 4 threaded rods to guide your SBF intake down is an awesome trick/tip.

 

Back in the 70's, before they made automotive silicone gasket maker, we used to use bathtub caulk to seal up the Chevy front and rear intake, instead of the rubber pieces. Even THAT worked well!

 

You're welcome. In another life I spent 31 years as an engineer at FoMoCo, mostly in engine development. At the Dearborn Dyno Lab we often had to run several components across the dyno engine, like manifolds, and it was common to just use RTV on the china wall.
Great job. Learned a lot.
Good times.
Behind me now. Just cruisin', racin', buildin', and occasionally relaxin'.

 

Makes you wonder why Felpro even includes the end gaskets in the kit when they’re not needed.

 

What’s an intake end gasket?

 

As usual with a question like this, you've now received every opinion there is, so you'll still have to make up your own mind.

 

By my count eleven of the 13 opinions rendered said the use of sealer in lieu of end gaskets works. That pretty well answered the OP's original question.

 

Nothing permanent about " rubber" gaskets that squeeze out / get hard & are , on their best day , difficult to install . The one piece pan gasket gave us relief from the old cork & rubber 4- piece sets , RTV , & " right stuff" gasket makers have given us better alternatives to the intake gaskets of the past , try & keep up .

 

Glad you went to the trouble to create a spread sheet. He still gets to decide for himself.

 

Does the engine have a properly working PCV system or road draft tube? Having the crankcase properly vented can help cure mysterious oil leak problems. Too much pressure or vacuum in the crankcase can attempt to displace rubber seals and gaskets.

 

One thing I’ve learned about using silicone sealer as a gasket is lay your bead down then put whatever part you’re installing (intake, thermostat housing, etc.) in place finger tighten bolts evenly then apply about half torque and let it sit overnight. The next day finish torquing bolts. Doing this prevents squeezing all the silicon sealer out of the joint and actually forms a gasket that when torqued has a squeeze and won’t leak. Your mileage may vary!

 

I put the manifold on the day I posted this-Monday. Decided that all by myself.

 

What’s an “rtv”

is that the blue stuff I find in oil pans?

 

RTV is "room temperature vulcanizing"; It has nothing to do with Mr. Spock though. It cures in the presence of oxygen at room temperature. GM has used both orange and blue RTV sealers over the years. Actually I think most, if not all silicone sealants are considered to be RTV.

 

The blue stuff I find in oil pans?

 

yeah, it room temperature vulcanizes in the oil pan, in the carb passages, all kinds of places folks put it.

hint: use it sparingly, and only for things like the ends of intake manifolds

 

So one tube per end

or one tube per intake

 

I've seen a few good ones...like using half a tube to install the oil pump gaskets on a flatty mopar 6, it wiped out the bearings. And the RTV plug in the gas tank pickup tube, from when someone installed the sender gasket with about half a tube.

 

I only ever use rtv regardless of engine. Many modern versions of older engines don't even have end gaskets in their intake gasket sets. For example every vortec sbc I've ever put an intake on only came with the actual intake gaskets and a small tube of rtv. As for rtv around coolant ports I've done countless engines dry. But every once in awhile one will decide to seep.....the 350 with performer intake in my 53 is one that seeped. Pulled the intake and smeared some rtv in a thin layer on both sides of the gaskets on all coolant ports and no more seep. If iron intake that hasn't been overly overheated you're likely fine dry