Vacuum leak

[Mac2Night]

So I have this pesky vacuum leak at my carb base on my '73 Explorer. The truck runs fine when it first starts up but as the choke opens the butterfly, the truck surges and eventually dies. I've checked everything but it still does this once the choke starts opening. But, when I spray carb cleaner at the base of the spacer, it levels off and runs smoother. Today I bought a new base gasket but when I looked at the spacer and the thin top carb-to-spacer gasket, it looks like there may be an issue. Any thoughts as to the spacer and gasket I have? What could be causing the manifold to carb vacuum leak?

Thanks for the help!

 

[twisted 66]

I would take a straight edge across the surfaces to see if anything is warped. Also you could use a gasket sealer like the one edelbrock made or gasgacinch or something like that.

 

[DJs74]

I'm not too familiar with the 2 bbl carburetors but assuming you have a factory Ford model, you might check or maybe you know if a Holley 2 bbl baseplate / gasket is the same configuration? If yes, you can probably get a thicker gasket and also in a broader offering of materials like rubber/composite type blends that might help to seal it up better.
As mentioned in the other post, you might have a warp problem either with the plate or the carburetor base.
You might also check to make sure the screws that secure the base to the body are tight - a leak between these two could be mistaken for a lower leak.
You mentioned "spraying"... (assuming its carburetor spray) and that it smoothed out or sped up - with a vacuum leak, the spray and mist will find and draw to the vacuum leak anywhere in the general area so it could be above the intake/spacer/base level and appear to be the base... not likely but probable.
As suggested, a good starting place would be the straight edge across the plate and base to check for flatness. I find that using this method with a light bulb in the background works good. If you have good flat table top or maybe a ceramic kitchen counter top, you could also lay your parts out and try to rock them on the flat surface... my wife really appreciates that approach!

You might also check any vacuum lines and fittings around the base as well as a cracked carburetor base plate.


Good luck, hope you are able to find the problem.


DJs74

 

[jckkys]

The imprint pattern in the gasket tells me you have a 2100 Motorcraft carburetor, and there's good contact over the whole surface. These carbs can be easily bent when the mounting nuts are over tightened. Yours doesn't look like that's happened. How's the spacer to manifold gasket look? The heat insulating thick carb to spacer gasket made for your engine looks like this;http://www.carparts.com/details/Ford/LTD/Felpro/Carburetor_Base_Gasket/1980/FP60716.html?TID=ecncse.

 

[Glass Pony]

Take a large flat honing stone, squirt a little oil on it and gently rub it on the gasket surfaces in a small circular motion. After a couple minutes you will be able to feel/see any high spots without distorting the surface.

 

[broncnaz]

Or you can use sand paper on a good flat surface and do the same thing something like 220 grit would be fine and help flatten it out. If its flat then new gaskets should do the trick.

 

[Rymadd]

Or you can use sand paper on a good flat surface and do the same thing something like 220 grit would be fine and help flatten it out. If its flat then new gaskets should do the trick.

A thick piece of glass works good for those without a surface plate

 

[Mac2Night]

Problem solved! I put a new remanufactured carb on yesterday that I got from a board member and shazam, the smoothest running Bronco I could wish for! Must have been a vacuum leak associated with the carb itself but I'll have to figure that out another day!

 

[Justafordguy]

Glad you got it fixed. Fixing your original and keeping it for a spare would be a good idea for sure.

 

[stevenson44]

Happy that carb is working for you Mac!


Sent from my iPad using Tapatalk

 

[Viperwolf1]

You need to get a bottle of compressed, liquefied vacuum to replace vacuum lost from those pesky leaks.