1958 Rochester 4GC Question

[Jon S]

I re-built a friends Rochester 4GC which was leaking gasoline between the throttle body and the bowl assembly.  Upon re-installing it on the car and priming it with a small cup of gasoline, it immediately leaked from the same area despite a new gasket.  We took it off the car again and since the rebuilding kit had multiple throttle body to bowl gaskets, replaced it with a gasket that had material 360 degrees around each barrel whereas the original gasket had four elongated cutouts like the original one and the one illustrated in the shop manual.  Reinstalling it and priming it again, the leakage was less; but nevertheless still present.

Am I missing something?  the four bottom screws are torqued very tight and there doesn't appear to be any warpage of the assemblies.  Anyone else had this problem?

[Jon S]

Maybe a porous bowl or hair line crack?

[Coupe Deville]

Hello Jon. I had the same problem with my 57 4GC. I took it off again after the rebuild and changed to the gasket that seals al the way around the barrels. It still leaked a little. I have sorta gone under the assumption that if you prime the carb with enough gas(pouring it in through the top) it will leak out. The same thing happens to me when I manually prime my carb. But when the engine runs it doesn't leak at all. I would start by priming the carb just a little and see if it will run. It shouldn't leak when its running.
This is just from my experience.   

-Gavin

[Jon S]

Gavin -

That was my thought, but coming from Carter AFB's I was a little concerned.  I much prefer the two piece design of the Carters!  Thanks for your reply!

[Dave Burke]

Hi Jon,

Have you been using gasket shellac?  It adds a chemical seal to the mechanical one given by the gasket.  Auto parts places carry it.  I shellacked my carb gaskets when I did the rebuild on my '57 4GC and that pretty much did the trick. 

HTH,

Dave Burke

[Jon S]

Dave -

I'm told shellac will not do anymore. The alcohol they put in the gas will dissolve the shellac.  I've rebuild over 50 carburetors and always installed the gaskets dry with no problems.  (This is my 1st 4GC in quite some time).  If it will run dry and hold gas when not in use, I will be happy.  I do not want any leaks to a hot manifold.  I'm told maybe a RTV might help, but am leary about using that on a carburetor.

[Dave Burke]

RTV might help, and I agree about the hot manifold.  Here in Alabama, I can still get alcohol-free high-test gasoline and I try to use it. 

Here is another thought, though you might hesitate to try it for cosmetic reasons: how about using fuel tank lining compound on the outsides or even on the gaskets themselves as a mating compound?  I lined my motorcycle's tank with it and use regular gas with 10% corn squeezins all of the time and it used to leak pretty badly.  I would think that if you coated the gasket with that and they did the assembly, it might be an idea. 

The only other thing that I can think of is very delicate work involving a vise and a bastard file...

Good luck!

Dave

[Dave Shepherd]

Check for warpage across the mating surfaces of each part?    No sealing compound should be used on any part of the carb, if needed it is a patch for what is really wrong.

[Jon S]

If I "prime" the 4GC with the throttle open, it does not leak.  I've tried priming this friends car several times but at best it runs for 2 -3 seconds and dies.  The fuel pump "appears" to be working as I can feel it pump air with a popping sound, but I believe he ran out of gas and there may be plenty of air in the gas line.  The glass bowl is dry.

My question - How to properly prime the car to get it started and hopefully the pump will draw gasoline from the tank that now has gas in it. 

[Coupe Deville]

I was in the same situation as you a few times. On my 365ci with the 4gc I had to replace the fuel pump. In this case I got a short pice of fuel line and a hose clamp. I slid the hose onto the pipe that is the vent for the float bowl and attached a funnel to the other end of the hose. Then poured gas in. It worked quite well to prime it. On my dads 390ci I did it a little differently. The car sat for years in the garage so all the fuel in the lines drained back to the tank. I had the original glass sediment bowl/filter set up. I removed the bowl filled it with gasoline and reinstalled it. I spilled a little fuel but it still worked well to prime the carb. But in both of these instances the fuel pumps were bad to begin with. I would say if your fuel pump is good and the float level in the carb is set right you should just be able to crank the engine over for about 15 to 20 seconds and it should fill and start.

Best of luck

-Gavin

[D.Yaros]

I routinely use the vent tubes to fill the fuel bowls in my carb when I start the car for the first time after it has been sitting all winter.  A ketchup squeeze bottle works quite well for this!

[Jon S]

Thanks Gavin & Dave - Good ideas!

[cadman49]

onge
I noticed nobody suggested setting the floats..for float level and float drop. the neddle and seats are  most likely "glued shut".first thing id do especially since it's been sitting all winter! this new gas is the worst thing for carbureted cars there ever was! the 10% or higher gas we have nowdays is corn alcohol. not good. alcohol absorbs water like a sponge and hangs on to it for a while,goes up stream to your fuel pump,carb. etc  guess what happens when that alcohol evaporates (as in real quick"?? it leaves behind the water,to make a gooy mess does the same thing to your gas tank and filters,especially a hot carb.,fuel lines etc. it gums up everything! especially the neddle and seats and mettering rods. look inside the bowl next time. it might have white  powdery stuff in there.  not good! most parts houses have an "antidote" for this condition,sorta!     r king cadman49