weber troubles

[turabaka]

Well I noticed today that I have fuel leaking from the base of the carb. I thought I'd solved that problem awhile back, but apparently not. So my question to all of you is, how do you get the weber to seal down properly? I've tried using just the gaskets, just formagasket, and the gaskets with formagasket on both sides.

[itzdave]

if uve tried some rtv and it still leaks, id imagine ya got somthin in the way. id take off the carb and see whats up, then ensure a smooth mounting surface, then rtv/gasket/rtv.

[turabaka]

which color is the right rtv formagasket to use?

[itzdave]

ive always used black. and thats all ive heard of people using unless ur doin super-high-temp stuff, then its some other color.

[88Accord-DX]

I used high temp., like 1500 or something. It's orange.

(which reminds me, I still need to tweek on some tuning with my weber)

[2ndGenGuy]

Are you sure it's leaking fuel from the base gasket? I would think that if it was leaking fuel badly, it would be leaking vacuum first and causing all sorts of other issues. I've got spots on my Webers where fuel kinda soaks through the gaskets, and leaves some nasty stuff on the manifold... but I've kindof accepted that as part of their charm. How much is it leaking?

[turabaka]

enough that you can smell it with the hood closed.

[2ndGenGuy]

You sure it's the base gasket leaking fuel? Not the top hat gasket? Maybe the float is flooding or something? Have you eliminated those as possibilities?

[2oodoor]

NEVER ever use RTV sealant anyhere near a carburator !!


I am about to find out what causes this when my 38/38 gets here, it is doing the same thing (buying it used)
I think it could be the fuel spilling over into the venturi on hard cornering, but the jury is still out.

[turabaka]

You sure it's the base gasket leaking fuel? Not the top hat gasket? Maybe the float is flooding or something? Have you eliminated those as possibilities?

considering I'm getting less than 3psi of fuel pressure, I think my fuel pump is dying, I highly doubt that it's the float bowl flooding.

[2ndGenGuy]

If the needle valve is going bad, then it could still be doing that regardless of fuel pressure. But typically if that's happening you'll have other driving issues. Like roodoo said, you shouldn't ever need any goop on your carb anywhere.

Maybe you need your adapter plates machined or perhaps it's time for some new gaskets.

[turabaka]

I doubt the adapter plates need machining since both the adapters, and the carb have only been on my car since late January. Maybe I'll just try cleaning the adapters off and reinstalling everything again.

[2ndGenGuy]

Yeah, I would make sure you bolt down the carb with the criss-cross pattern like when you do your wheels. You'll find that when you get the last bolts snug, the first two will be loose again as it squishes the gaskets. Also, make sure that the carb studs that went into the lower adapter plate aren't pushing through and lifting against the lower adapter plate.

[cygnus x-1]

With those adapter plates, always use thin gaskets between them. Otherwise they have a tendency to warp when the bolts are tightened. And don't crank them down massively tight either. Fairly snug is fine.

C|

[itzdave]

so why is rtv such a bad idea?

[2oodoor]

Yes the only thing I use is very little permatex hi tack to hold the gaskets in place, not even enough to squeeze out or build any layer.
It is strange how these can leak gas yet not leak vacuum. It has to be dripping down or possibly the base gasket protruding thru below the throttle plates and blocking some of the mixture and holding it till it is liquid again. It could be chruning up some in th bowl too, foaming up from the blends of gas we got now. The sealing surface between the bowl and venturi is not that big either.

[2oodoor]

so why is rtv such a bad idea?

Hard to write it down to explain the science about silicone molecules and those mixed with butyl solids blah blah blah, but it is a mess and gets everywhere including inside your carb and motor.

I think these 38/38 carbs have a lot of turbulence in the venturi area, considering the manifold being cut out too. Ok call me crazy but if you ever been to a car wash that used the turbo blasting fans to dry off the car, watch the water as it goes off the car. All of it can't go straight off the car and it will wander around like little squiggly ameoba :nuts:and some gather back into larger forms until it is dispersed. OK that is what is going on inside the venturi. That must be how it is able to seep into these areas around the carb base, again. I am thinking the gasket is protuding some and thick gaskets will make the situation worse as well.