I just had a Q-Jet returned to me for leaking fuel. The main metering well plugs were leaking, which is not at all unusual. The disturbing part is that I had recently rebuilt it, and epoxied over the main and secondary well plugs. No, I didn't miss, but the fuel dissolved the epoxy. I'm guessing it may have something to do with the ethanol and/or fuel additives, since this is the same epoxy I've been using forever (Conap E-Z-Poxy) and it has always survived heat and fuel.

What are you all using to seal against fuel? The epoxy I applied had turned clear, then to a goo, It's still in a gelled state, and had even dripped onto the gasket/spacer and was soft enough to wipe off with a cloth. I know it was cured when I assembled it. Beware!

 

I have never used epoxy on carbs, but I have only rebuilt holly's

later

rick

 

The Q-Jet was replacing a Holley. The Holley replaced an Edelbrock AFB. The AFB dogged at low RPM (14" Hg. vacuum). The Holley wouldn't idle despite several metering changes. It ran best by far with the Rochester until the plug leaks started fattening up the idle. Looks like I'm still hunting for a new type epoxy.

 

what about edelbrocks epoxy? they claim it's fuel resistant, and i'm guessing of all companies that would actually test that, edelbrock would be one..

 

jb weld has been working good in my modded holley dp for a long time

 

Thanks. I'll check into those. Obviously, my old standard isn't going to cut it any more.

 

hello
how much fuel presure are you using? I would sugest a regulator just incase your fuel pump is spiking on you? I would try that elderbrock epoxy like stated before . I talked to the guy who dose carbs in this aera and he said that he dose not use epoxy--I guess to each his own

later and

GB

rk

 

The only "pressures" that affects the well plugs are the delta-pressure between the manifold and atmosphere, and the fuel column height - i.e., gravity.

I've used JB Weld with 10% ethanol with no problems, but I don't know about some of the latest stuff out there.

 

I think I many have found a suitable replacement. The package claims fuel and additive resistance. I've got about 50/50 gasoline and ethanol soaking in the bowl now (yes, the brass float has been changed out for plastic).

The old epoxy just let go:

 

I usually use JB weld. It seems resistant to fuel, but it doesn't seem to like EGR gasses.

 

newer gasohols are more prone to breaking down expoxies, in fact those using clear sight plugs should note that mr. gasket and holley both came out stating that they should NOT be used when gasohol fuels aka 10% ethanol or more are being used.

 

while I don't doubt that changing fuel mixtures are are a very likely culprit, you may still want to mix up a another batch of your old reliable epoxy and do a test just to see if it dissolves again. this could rule out any inconsistenty in the mixture of the plugs that did dissolve (maybe that batch didn't get enough hardner or resin?)

 

I think you've identified the problem. The old Conap has always worked well. I either didn't mix correctly or the shelf life has long since passed. I used a different product and soaked it in 50-50 ethanol/gasoline and had no softening.

I think perhaps the original coat of epoxy never fully cured. Either way, the problem is solved.