The Stovebolt Site Forums The Shop Area Engine Shop Carb Question

I rebuilt my carb and was getting ready to install it when I got stumped. Attached is a picture of what I think they call the insulator block, the bottom of the carb, and the gasket that came with the kit. It looks like the gasket is not right. Can anyone enlighten me on this?:

http://s7.photobucket.com/albums/y2...mp;current=carbandmanifoldinstall023.jpg

Also, I found this piece of screen between the bottom of the carb and the intake manifold. Does anyone know why it might have been there? You can see the gummed up gasoline in it:

http://s7.photobucket.com/albums/y2...mp;current=carbandmanifoldinstall024.jpg

You have the right insulator for your carb, but the wrong gasket for use between the carb and insulator. See how the dimple on the insulator goes under the port on the bottom of the carb.

FWIW - I do not use gaskets on the carb, insulator, and manifold on my '54 3100. My insulator seals against the carb and against the manifold. I tried using a gasket on each side of the insulator, but that made the carb sit too high and the accelerator linkage to the carb too short. If your insulator is a reproduction made from hard plastic, it may need gaskets.

The screen looks like it was cut from Mom's window screen and used to keep out flys (?)

Ha. No idea about the screen. My insulator is hard plastic. Would the correct gasket have a notch for both dimples in the insulator? If so, I can probably just make one.

I take it the screen is not Chevrolet issue, huh?

The "correct" gasket would have four cutouts so that it will fit no matter which way it is installed. You only need one cutout - to fit under the port on the carb. The cutouts don't affect the seal at the insulator to manifold.

I'm sure that others can give you good info re: gaskets.

If it looks like one or two gaskets will elevate your carb to where the throttle rod to the carb will be too short, then ... My uneducated suggestion would be to lap both sides of the insulator with sandpaper glued to a flat surface such as a table saw, jointer, or plate glass. That will make it truly flat so that you will only need a thin gasket(s) to seal.

Joe -

I enlarged the pic of your insulator. It looks like an original bakelite insulator, not a plastic reproduction. You might try mounting the carb and insulator with no gaskets and see if it seals OK. Don't lap it. Use it as is.

>> I may be talking out of my a**, so don't take my advice as gospel. I'm no expert. Others with more experience can give you better info.

I bought my insulator from a forum member. It was an original bakelite insulator, but it had a slightly soft coating on the surface. May have come from the factory that way, or it may be varnish from old fuel. Either way, it sealed the junctions to the carb and to the manifold.

OK, thanks Lonnie. I think I'll try it with a gasket first and see how my throttle linkage winds up.

Other 'Bolters - please give your input. I may be all wrong.

Make sure that the port under the carb is not covered by the gasket. If you use a gasket under the carb, either buy a correct one, or cut out a spot on the one that you have.

I've always used gaskets on my insulators. Underneath the insulator, I've always used one of the really old asbestos gaskets, as I had a bunch of 216 ones. On top of the insulator, there always seems to be a paper gasket in the kit that works fine. I've never actually put my foot to the floor, I just downshift and enjoy the scenery!


The screen looks like a back fire spark arrestor screen.

Or maybe the truck lived where there were lots of those mud dauber wasps!

Found the right gasket for the carb and used gaskets on both sides of the insulator. Started the truck for the first time since I got it a week ago and it will run for a few seconds, then stop. I have a leak at the butterfly valve shaft at the bottom of the carb, for one thing, but don't know if that's related. I looked down the throat of the carb and pumped the throttle once. I saw a jet of gas shoot down the throat. Should there be just one stream or two? The jet was toward one side of the carb and I thought I saw a little dribble coming from the opposite side.

The screen is definitely not original equipment. Some aftermarket places like J.C. Whitney sold similar items as "gas savers" intended to break up the gas/air mixture into finer particles and supposedly improve gas mileage. This one looks like a homemade copy of one of those things. I call those kind of gimmicks P.T. Barnum Specials ("There's a sucker born every minute!")

The accelerator pump only has one outlet, so a single stream is OK. If it's stumbling on acceleration, you might have a vacuum leak somewhere, or the ignition timing might be a few degrees late. Try loosening the clamp around the distributor housing and turning it just a little counterclockwise - - - -don't overdo it, a little adjustment goes a long way.
Jerry

Thanks, Jerry. I discarded the screen. As soon as I get my battery situation sorted out I'll be able to concentrate on the fuel delivery.

If you are dripping gas into the throat after you shut it off, you are flooding. There is probably a piece of dirt in the needle & seat or the float might be full of gas. Too much fuel pressure can also cause this. Gas will not come out the throttle shafts unless it is flooding.