1972 Thermoquad (340) Main Jet Well Inspection Question?

[dibbons]

When I rebuilt the Thermoquad I was pleased to find the main jet wells had not become unattached so I did not service them in any way.

Now with carb installed and vacuum leak (idle increase with hand placed over air horn) I removed the carb for inspection. I find the main jet wells are still attached as before. However, I did find little puddles of gasoline in the little depressions they sit in (where the green handle is pointing). Is that normal or a problem? Thank you.

 

[dibbons]

Update: After removing the gaskets, I thought for a moment I found a second gasket stuck onto the plastic body, but even with a razor blade it won't budge. Looks maybe it was made that way where the body is not even all the way around. The large hole near my finger is lower than the adjacent small hole where I suspected the gasket (or gasket remnant) was still stuck on there. Still not sure. (see photo)

 

[Bewy]

Could be normal......if there was fuel in the bowl when you separated the bowl from the base. Fuel could have sloshed out into those cavities. To test: set bowl up on bench so that you can see the jet wells. Carefully poor fuel into the float bowls to just cover the wells; an eye dropper or syringe is a good idea, as too much fuel will run over the edge making it seem like you have a leak...when you haven't; look for fuel weeping from the wells.
Carb looks to be in EXCELLENT cond.
Leaking wells do not affect idle, but can make the main system rich.
To fix leaking wells: use a hacksaw blade or triangular file to remove the old epoxy. Re-fill with fresh fuel resistant epoxy. Do NOT put too much epoxy on or you will break the gasket going over the epoxy 'lump'.

 

[RustyRatRod]

Update: After removing the gaskets, I thought for a moment I found a second gasket stuck onto the plastic body, but even with a razor blade it won't budge. Looks maybe it was made that way where the body is not even all the way around. The large hole near my finger is lower than the adjacent small hole where I suspected the gasket (or gasket remnant) was still stuck on there. Still not sure. (see photo)

View attachment 1716490266

The gasket does not seal that area. That's normal. That's the hole for the air cleaner stud.

 

[dibbons]

Carefully poor fuel into the float bowls to just cover the wells; an eye dropper or syringe is a good idea, as too much fuel will run over the edge making it seem like you have a leak...when you haven't; look for fuel weeping from the wells.

I used gasoline and it took forever but finally was able to find a tiny damp spot on a toilet tissue on the passenger side. On the driver side either nothing or it took forever to find any damp spot.

I used alcohol for another check afterward. Same results but it took even longer to find anything.

Since I turned the carb upside down a few times before disassembly to drain fuel out through the three carb vents, I don't really know how much fuel had collected in the two little wells. Now that I find how small the seepage is, I might not go to the trouble of tearing them off and re-attaching (might make things worse).

I did order a product RustyRatRod recommended in his Thermoquad rebuild article called "Seal All". I don't normally believe coating things on the outside are effective, but in this case I might just put a thin coat of the Seal All around the existing epoxy.

 

[RustyRatRod]

Get you a tube of this.

https://www.amazon.com/Seal-All-380113-Adhesive-2-Ounce/dp/B0015AE0AU?tag=fabo03-20

It works GOOD. It's runny, so get you a little brush and brush a coat or three on the seam where the main jet wells are glued on. It's also impervious to gasoline, which JB Weld is NOT. So it will last. No need to remove the main jet wells. Just clean them up good with isopropol alcohol, let that dry good and apply the Seal All.

 

[Bewy]

You do not remove the wells!! Procedure in post #3 cleans out the joint ready for fresh epoxy. I do this procedure to every carb that I am going to use these days because the epoxy is so old. I doubt what you have found is causing a problem.

 

[dibbons]

You do not remove the wells!! Procedure in post #3 cleans out the joint ready for fresh epoxy.

Thanks for the clarification.

 

[Bewy]

If you have JB weld, you can use it. It is fuel resistant.

 

[RustyRatRod]

If you have JB weld, you can use it. It is fuel resistant.

No, it's not. You're mistaken there. I've seen it let go a lot.