Tricks to sealing the intake Cheap wize!!

S

SavageBlunts904

New Member
I am running a cns carb on a small intake tube and i think i am having a problem with vacuum leaks. What is the most reliable way to seal off the intake without buying a new intake manifold. Which is what i am going to eventually do in the long run.

Thanks for your replies.
 
I tried useing gasket seal II on the nylon bushing- it works for a little while. If you don't mind periodically taking it off and re-applying, it's not too bad. As it is, I am experimenting with an aluminum bushing that others find to their likeing- mount it and forget it.
PM me if you are interested
 
I have never had any problem with leaks on my CNS carb. When I installed the intake manifold I used gasket sealer on the motor and manifold, I don't use any sealer on the junction of the intake and the carb. The rubber grommet in the throat of the carb seals just fine for me, the white spacer is just that, a spacer, not a seal. I replaced the original screw and nut on the throat of the carb with one that I can tighten better and that pretty much did the trick. When I install the carb I push it back until it bottoms out, then wiggle it a bit until it slips into the divot in the black seal, then while pushing it firmly on toward the intake I tighten the screw. (pull the black seal out of the carb once and fit it on the end of the intake to get a feel for what you are dealing with) I have never had it come loose or leak on me so far in 1000+ miles...
 
Nightcruiser's advice is right on when it comes to the 'O' ring. Just because there's an 'O' ring there doesn't give you a positive seal. The carburetor must be pressed tightly against it, not just pushed on before tightening the clamp.

As for sealers, you must read the label on any product you plan to use. MOST silicone based gasket sealers are NOT compatible with gasoline. Yes, they'll seal, for a while, until the gas attacks it and it turns to goo.

The SealAll product is unbeatable. It is formulated especially to work when in contact with gasoline, even gas with ethanol. Use the RTV stuff for other things but don't expect it to last long if gasoline, or gas fumes are present.
Tom
 
I've had a leak problem with a 66 speed carb- the "o" ring seems to help, but the real source seems to be that the slots cut in the carb intake sleeve extend back too far- past the clamp-

It started when I switched from the original longer billet intake to the newer shorter one, which doesn't seem to then extend up the sleeve to cover the long slots as well. If I had a soldering iron (Lost mine in the flood and never replced- I might try to put some flux behind the clamp and over the slots- an o ring inside and an electrical tape wrap under the clamp on the outer carb sleeve seems to be doing a good job. The tape bunch up when I put the carb on, but still covers the long slots.

I guess you could use JB Weld or that stuff above or maybe just gasket goo, but that would be sloppy. A rubber OUTER O ring woyuld be good behind the clamp. I had put a nylon tie on it but that didn't work- one with some rubber under it probably would-

If the tape fails, that's what I'll try next.
 
You are correct about some of the slots being machined too deep. I've seen this on several NT style carburetors. When this happens you have a built in vacuum leak. I always fill those slots with sealant making sure they are completely filled front to back.
Another helpful hint is to sand, or rough up the intake manifold where the carb will attach. The older aluminum manifolds weren't bad but the chrome plated steel ones need to be roughed up some to give whatever sealer you use a better 'bite'.

Tom
 
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