Inlet Gasket sealer and gaskets

[karter13]

Hi all

Why do you put gasket sealer/cement onto the carburettor to manafold joining face when there is already a gasket there.

Does not the gasket alone not do the job of stopping leaks, why do you need a sealer also

[SupStk]

Where did you hear that was a recommended practice?
Sealers of any type have no business near a carb.

[karter13]

A graham bells book, tonight I will take a photo of the chapter concerned.

[karter13]

Supstk
I took a photo but it says photo is too large so I'll do it the old school way

In a graham bells book he says
Manafold air leaks
The mixture ratio is also affected if there is any air leaks, so you must be very careful to seal the manafold to the head, and the carburettor to the manafold, using the correct gasket and the right type of gasket cement

[Schurkey]

The "right type" of gasket cement (sealer) can be "none".

[SupStk]

If the mounting surfaces are flat, I haven't had any issues using nitrofill gaskets (Mr. Gasket or such).

[peejay]

Once I started using my smoke tester on things besides evaporative emissions systems, I stopped trusting any paper/cardboard type gasket to seal air.

You don't need to necessarily use a kind of sealant, a thin wipe of grease will work just as well. The part will come off more easily in the future as a bonus.

We're not necessarily talking about vacuum leaks large enough to affect carburetor metering, but if you're diligent about making sure all air going into the engine is filtered, it's absolutely critical.

(Addendum: I absolutely WILL use a smear of silicone inside the WATER JACKET connection, to keep coolant from contacting the gasket, so that inside the cutout there is a direct head-silicone-manifold barrier. I have been burned by way too many "Mr. G" gaskets that weeped coolant THROUGH the gasket!)

[SupStk]

We're not necessarily talking about vacuum leaks large enough to affect carburetor metering, but if you're diligent about making sure all air going into the engine is filtered, it's absolutely critical.

Dirt passing through the base gasket? Thats something I never considered.
If thats the case how much do suppose is going through the filter media, between the filter to air cleaner to airhorn connections?

[CharlieB53]

I don't trust paper gaskets to seal much at all. I am a very firm Believer in silicone sealer.

HOWEVER, silicone is only to be used as absolutely thin as you can smear it, and you must allow it time to almost dry before assembly.

It only takes a little dab which can be smeared out to cover quite a lot of gasket area.

[peejay]

Dirt passing through the base gasket? Thats something I never considered.

Once you have to tools to quantify something, the tendency is to push the turd-polishing as far as you can

I will allow that a Holley 4150/4160 carb leaks air like a colander. It seems like almost all accessory holes in the sides (choke mechanism mount holes, etc) go through to the venturi area. And of course the giant hole up top where the choke rod goes through.

Fun was the time I smoke tested the intake on a tri-power GTO. Stuck rubber gloves over the air horns and sat the air cleaner bases on top to hold them in place. Found out that the carbs had been rebuilt with the wrong gaskets, and while the rear carb's glove stayed down, the front carb's glove inflated, proof that the throttle plates weren't airtight. (On the GTOs the end carbs had no idle circuitry at all and needed to be SHUT at idle so they didn't pass air)

If thats the case how much do suppose is going through the filter media, between the filter to air cleaner to airhorn connections?

Stick a blob of Vaseline or other clear greasy substance somewhere downstream of the filter media and observe it. If your filter ain't filterin', you'll see the evidence.

[Schurkey]

I don't trust paper gaskets to seal much at all. I am a very firm Believer in silicone sealer.

HOWEVER, silicone is only to be used as absolutely thin as you can smear it, and you must allow it time to almost dry before assembly.

It only takes a little dab which can be smeared out to cover quite a lot of gasket area.

I used to "rubber-coat" paper and cork gasket material. I quit when I realized that the problems I had with gaskets squeezing out-of-position was due to the slippery nature of RTV silicone.

Now I use any one of several gasket adhesives--Gasgacinch, Copper Coat, High Tack, and similar. On a particularly difficult intake manifold, I even used plumber's Teflon paste. Holy crap, that worked well. Very difficult getting the manifold back off, though.

Everyone here already knows this, but just to say the words...CLEAN and FLAT gasket surfaces are essential.

[CharlieB53]

I always allow time for a thin layer of silicone to 'dry' before assembly to prevent, or at least minimize the possibility of a gasket squeezing out. Adhesives also have to dry to a 'high tack' state prior to assembly as used to soon came also still be to 'slippery' to adhere will and can slide and tear.

Practice. Too thick a coating, too soon assembly, both not so good.