VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Vacuum Tank grrrrrrr

Lessons learned. For the past month the FB50 would start and run great for several miles then began to cough and sputter and backfire and barley run at full throttle. I cleaned the carburetor every time the problem occurred, and cleaned the plugs and set the points and the timing nothing cured the problem. Some times it would run two or three miles some times it would not get out of the drive way. A very frustrating situation. Because I couldn’t think of any thing else to do I checked the oil level out of boredom. I found the crank case was over full and very thin. It had gasoline in the oil. Disconnecting the vacuum line from the vacuum tank the engine would run fine, hook up the vacuum line to the tank and instantly it would start to cough and sputter. I removed the top of the tank and found the vacuum valve was not shutting off. A good cleaning and we went for a 15 mile drive and it didn’t miss a lick. I think Louie Chevrolet has been up there laughing at me all this time.
Hutch

Good to hear you are motoring along well now Hutch. And yes, old Louie Chevrolet would have a good laugh at some of the things I've done too.
My 27 won't go at all now because I can't stop the carburetor from flooding everywhere. The needle valve is not shutting off the fuel supply. Can't be my electric pump as the same one has been in there for 28 years without a hassle. Float may be getting stuck on the fuel bowl maybe. More experimenting. Old Louie would be hysterical by now.

If you find no problem with the float in the carby, you make have a bit of muck in between your needle and seat. I once removed and did a mini lap in like a valve grind, but made sure it was 100% clean before I re-installed. Fixed the problem . Worst case you make need to replace them.

No chance your elec pump has gone crazy and uped the pressure?

Regards

Ray

Hey Thutch7244. Your lucky it did not detonate in the sump, which happened to me a few years ago. Car was running very rough during final stages of restoration after I fitted a carby had been purchased as a supposed reco. My friend had been under the bonnet all day, playing with the carby settings, no luck. He went home, I started the engine once more, ALL MIGHTY BANG AND BONNET LIFTED AND ENGINE STOPPED, SMOKE EVERYWHERE.
The sump had detonated and blown the oil filler cap off so hard it struck the underside of the bonnet and made a dent 3 inches wide by 1/2 inch deep right where my friends head would have been, not to mention damaging my new paint work. Would you believe no other damage to engine, which is still going strong over 30 years later. I have heard of detonations blowing the sump right off. As for the carby, pulled it off threw it in the corner never to be spoken about again. Fitted another carby with new jets etc, ran perfectly first time and 25 years on.

SO AS I SAY YOU ARE LUCKY.

Regards

Ray

1928isgreat, Yes, I know how lucky I am. I have heard of engins blowing up because of fule in the oil. It just didn't dawn on me that an up draft carburetor could leak fuel into the cylenders. Of course I now know that the fuel was being sucked into the intake manifold through the fule pump.

Ausiechev, I stopped the needle and seat from leaking using car polish with a very fine grit (it was all I had handy). Put the needle in an electric drill applied polish to the tip of the needle, removed the seat from the carbuerator, stuck the needle into the seat and holding the seat in my hand began a power laping of the two. Replacing the polish on the tip of the needle every minute or so for about ten minutes. Cleaned the pieces and put it back together. stopped 98% of the leak. Sounds like the same thing that 1928isgreat did to his carb. I would say great mindes think alike but Louie and I are woried about mine. Hutch

Hutch your idea of lapping the needle valve sounds like it's worth a try. The needle does have some score marks on it. I'm told that in the absence of grinding compound, toothpaste works pretty well too. I'll try that using slow speed in the cordless drill. A new needle and seat might be the go ... if one can be sourced.

If you read my other post, i just had my carb experience the same, where fuel flow would not stop. I thought it was the needle valve, but in fact it was just a loose seat, so gas was seeping past the threads.

Thanks Shawn, but the seat is really firm and no fuel is coming out there. It's flowing out the top of the float bowl and even into the air inlet if I don't turn it off quick enough. In all the years I have had the car it has never done that. I don't think the float is lifting at all to shut off the needle valve but I can't see anywhere is could be binding. Tried a new float bowl with no difference.

aussiechev,

Have you checked to make sure there is no petrol in the float? It is not unknown for old brass floats to develop pinhole leaks which allow petrol to be drawn into the float, which then floats lower than usual and may not be high enough to cut off the fuel supply when the float bowl is full.

If fuel has got into the float, submerge it in near boiling water, which will vapourise the fuel and show the location of the leak. When no more fuel comes out, remove from the hot water and let it cool. When cold seal the leak with a dab of ordinary tin/lead solder.

Frank.

Frank,
Thanks for your suggestion. There was a miniscule hole in the float but the float was so light there could be no fuel inside. I guess you could feel the weight and the fuel moving inside if it had any in it at all.I didn't put the float in hot water but did seal it with a light covering of solder.

By not purging the float you may have sealed fuel inside. If you still have problems you may look at the float again.