Carburetor Leak - Warped Cover or Float Setting Wrong?

[AACA Library]

I am getting a leak from my carburetor bowl cover where it meets the bowl. I have the screws very tight but I dont know if the leak is from a bad gasket, warped cover or bad float setting. Any tips on telling the difference?

I did check the cover with a straight-edge and it was flat when I had it off.

Thanks,

-Chris

[Guest Grant Magrath]

Combination of float set too high and over-tightened air horn screws. On the Rochester Q-Jet, over tightening the air horn can warp it quite badly and ruin it.

Cheers

Grant

[Mark Shaw]

Chris,

You didn't mention what year or if you have a Marvel updraft carb, but it is common for the casting to warp. If this is your carb., I suggest you check the flatness on top of the bowl to see where you may need to file down some high spots to get a good seal. Also, as Grant suggested, make sure the float is adjusted. I have the fuel level about 1/8" below the jets on my cars.

[AACA Library]

It is on a '37 Buick, it is a Marvel CD1B

[Guest outlaw car man]

Sounds like your lid is OK and straight and all, as Mark says, get it flat and clean as possible.

Float is critical as is the needle & seat, not in range but critical.

My Marvel book for the CD-1B : " Remove bowl cover and float assembly and turn it upside down. Proper setting of the two floats on the assembly should measure 1/4 "from bowl cover gasket to closest surface of each cork float. Be sure to check both floats to this dimension"

I'd get this done, adjusted 3 times to make sure you are on target.

I then take a toothpick and run a small flat bead of gasket cement & sealer around the inside edge where it is going to meet. In other words where it will join away from as much gas exposure as possible. Use your gasket too of course. Let get tacky and join. I thighten it hard but not like as hard as I've ever done on anything ( hope that makes sense ) Wire off any excess that is squeezed out.

Let it sit overnight- This should seal the bowl & cover, assuming warpage isn't critical. I assume you don't have a top vent on it like the 33. Pictures don't show that.

Give it a shot.

[Mark Shaw]

Chris,

One more tip... Use gasket sealer only between the bowl and the gasket. This will compensate for irregularities in the mating surface & slightly raise the depth of the bowl. The gasket should seal by itself to the lid & allow the lid to be removed without distroying the gasket.

This works well on cork rocker cover gaskets to create a shallow basin to keep oil from running down the sides of the engine when the cover is removed....

[AACA Library]

Thanks guys! I spent all weekend bending, flaring & installing new brake lines (no leaks there!!!) so I didn't get to address the carb. I will try early this week.

[Pete K.]

Chris, If you still have a problem with the carb spilling out and mating surface/gasket is verified good, it is your old cork float. Over time, they shrink and rot and become non-buoyant. A NOS cork float is expensive and you're still getting a 74 year old piece of cork. Try locating a "composite" material float that some parts vendors sell for other cars. It may be adaptable to your carb.

[AACA Library]

I made new floats (and covered them with POR-15) and my leaking issue was a result of my float settings.

Now my carburetor doesn't leak at the bowl cover but I am having trouble keeping it running at low RPM after the car warms up. She starts right up and idles fine. Then, after a few minutes, a hear what sounds like a sucking sound out of the top of the carburetor and the engine slowly bogs down until it stops altogether. If I press the accelerator and keep the RPMs high the engine runs fine

Perhaps I have my floats too far the other way now and the fuel pump can't keep up at low RPM?

Anyone have a Carter WDO for sale? :-)

[Mark Shaw]

Chris,

If you can keep it going by pressing the accellerator, it probably is not your float setting. It sounds like a choke problem.

[Pete K.]

Or can be an idle bypass orifice clogging up.

[Guest Grant Magrath]

Yeah, if it was leaning out, the revs would increase most likely. Take the air cleaner off and observe what happens. Mark could be onto something with that choke idea.

Cheers

Grant

[Guest outlaw car man]

Just throwing this out as I'm not that into the 37 40, but, I;ve experienced the same with my 33 ( in the past ) . Low, intermediate or high speed jet gummed up.

Vodka gas evaporating leaving gum-

Starts back firing like it's running out of gas and laboring. Hate to see you pull it off, check the choke first.

Warms up, then stops- sounds like you are using up the gas in the float bowl, then chokes out. Float/needle/seat.

Keep at it.

[carbking]

Chris - is the choke butterfly completely vertical once the engine warms? If not, the engine may be running too rich rather than too lean.

Jon.

[AACA Library]

Well, last night I started the Buick up and after a few seconds it died again as described. I was looking in the engine compartment when it died and gas started coming out the accelerator pump shaft and also a little port next to it. So, thinking I had too much gas I really set my floats low.........then the same thing. Since I had new floats with POR-15 I didn't think that was the issue, but it was. I guess I didn't seal them well enough because they didn't float and when I squeezed them I could see that gasoline had penetrated them. Now I will try super glue on new cork and hope for the best.

Thanks for the suggestions, they are all quite helpful for a newbie like me.

Chris

[Mark Shaw]

Make that Krazy Glue brand... I know that stuff works...

And you can gt it in a fingernail polish size with an applicator brush.

[AACA Library]

Thats exactly what I am using Mark. Goes on purple and dries clear. I think I am going to make an extra set and throw them in the glove box just in case the current set fails miles away from home.

[Mark Shaw]

You got it...

Good luck,

[carbking]

Chris - the seal must be made after the float pontoons are attached to the arm; otherwise, the seal will be broken at this point. Sealing up a couple of spares would be futile, unless you also have a spare arm with which to attach them.

While we use only the new foam, we used cork back when we could still get natural cork (the ground and glued "composite" cork is heavier than fuel and won't float before it is sealed).

A tip on sealing cork:

Lightly heat the cork (125 degrees in a toaster oven or sit outsite in the sun in the summer) prior to dipping in the sealant. Then since the sealer is cooler than the cork, the sealer will be pulled into crevices and thus minimize air bubbles. And DON'T use your wife/girlfriend's toaster over, or you may end up being toast!

Jon.