I finally got sick of it taking 20 seconds for the vette to start up everyday, so I puled the carb and have it torn apart and am going to epoxy the well plugs.

ANybody have a picture of which plugs to epoxy? I am pretty sure I know which ones but I only want to have the carb torn down once.

 

Mike -
A couple of rambling thoughts and opinions on this subject:

First, the plugs are actually seldom the problem. The following issues can cause the problem you're having:

1. Bad fuel pump, allowing leak-back through the pump. If the checkvalve in your fuel pump is not sealing right, the standing fuel in the fuel line between the pump and the carb will start to leak back down through the pump. As this happens, it will actually siphon the fuel right out of your fuel bowl swince the needle/seat on a Q-Jet sits in the bottom of the bowl. To prevent this, you can do one of 3 things:
- replace the fuel pump
- Install a fuel filter with a checkvalve in it (available at NAPA)
- Install a needle/seat assembly that does not have the "vent" holes in the lower part of the seat - this prevents the fuel from leaking out of the bowl.

2. Oxygenated fuels. Many fuels around the country have ethanol (alchohol) added to them. This increases the vapor pressure of the fuel, and contributes to the fuel evaporating out of the bowl. If you have ethanol "enhanced" fuel in your area, you may be stuck with the dry-up problem.

3. Bad float. If you have a fuel-soaked float in your carb, it may drop down too low after shutdown and pull the needle off the seat. This will allow the fuel to drain back and siphon out of the carb. To correct this, you can replace the float and remove the clip between the float and the needle to prevent the float from pulling the needle off the seat.

4. Last, the leaking fuel plugs. In 25 years of building Q-Jets, I have seen 1 (ONE) Q-Jet with leaking plugs. The plugs in question are the primary well plugs and the secondary well plugs. With the throttle plate removed off the bottom of the carb, these are the two big silver plugs in the middle of the carb (secondary well plugs) and the two smaller plugs right at the bottom of the protruding casting slightly forward of the secondary plugs. You can test these very easily: Just pour a little gasoline or lacquer thinner into the float boal and set the float bowl up level on your work bench. After an hour or so, check the well plugs to see if they're wet. If they're not wet, the plugs don't need to be sealed. If they're wet, you need to seal them.

If you need to seal them:
The secondary plugs are best sealed by simply using the well gasket seal found in any Echlin brand carb kit. Echlin provides a rubber gasket that drops into the well recess in the throttle plate, and this will seal the secondaries.

Sealing the primary plugs by simply coating them with epoxy is a waste of time: The epoxy will quickly leak, and simply doesn't work. If you want to permanently seal the plugs, drill the plugs and tap them for a 10-32 screw. Buy a couple of 10-32 x 1/4" countersunk allen-head scews from a good hardware store. Coat the screws with JB-Weld, and screw them into the drilled plugs. This will positively seal the wells, and they will never start leaking again.

Good luck!!

 

Great info Lars! I have a similar problem with my 73 Olds 442 and was planning on replacing the fuel pump first (in line with your advice). As far as fuel filters, mine is the bronze stone - in the carb, and I have a solid metal line between the fuel pump and carb. Any suggestions/recommendations as to how I should install a fuel filter with a check valve?

 

Thanks for the help Lars,

First off, The primary well plugs are gasoline soaked drying them off and letting the carb sit with some fuel in the bowl. W
hen I try and start the car every day, I hit the pedal to actuate the accel pump and there is no fuel coming out of the carb like normal.

I beleive the problem started after I made a steel fuel ine for it, I used the fuel filter from a TBI chev truck. maybe one of my flared ends or the o-ring gaskets on the fuel filter fittings is leaking air?

I have epoxied up the primary well plugs for now to see if that is the problem if so I'll probably go back and tap in a set of 10-32 screws like you said.

 

Denney -
The fuel filters with the check valves are available as stock, in-carb filters, replacing the bronze unit you cirrently have - no need to break into your steel fuel line. Just tell the NAPA counterperson you want a Q-Jet "shorty filter with check valve."

MikeC -
If you have observed the plugs turning wet, you certainly have a well plug problem. The filter you installed would not have affected this in any way. You can try the epoxy thing first, but if the problem persists, do the drill-and-tap procedure I outlined: it's very permenent....

 

 

Thanks for the pic Turbo-Jet. I only did the primaries as the secondaries seems to be fine. I am going out to put the carb back on.... I love being on holidays!

I also have a stock quadrajet filter with the check valve that I'll use if my leakdown problem persists.

Thanks for all of the help guys!