1951 Hudson Carburetors

[Deleted User]

1951 Hornet Carburetors

I am wondering if anyone can help me with a problem that a friend of mine is having with his car. When you start it up gas will leak out of one of the carburetors sometimes. If you tap it it stops leaking and all is ok. I took the rear carburetor apart and could not find any signs of what would cause the needle to stick and ther float level was correct. When I went to start up the engine it leaked, I tapped it and no more leaks. A few days later when I started the engine it was the front carb that leaked. I talked to the previous owner and he tells me that it did this when he owned the car and all he did was turn on the electic fuel pump and check to see if either one of the carbs was leaking and if so he would just tap it on he would not have any more problems that day. He also told me that he had had the two carbs rebuilt and it did not make any difference. He also tells me that he was told that Hudson published a bulletin on this problem and how to correct it but he has no other details. I have checked on the web to see if I could find this information but have had no luck. I am wondering if anyone knows what the cure is for this problem. The new owner of this vehicle is looking for me to cure the problem as like he says it is not acceptable the way it is now. My thoughts are if some one already has come up with a cure it sure would save me a lot of time and frustation in trying to solve it.

Also on the plumbing of the fuel lines to the carburetors the main feed line from the mechanical fuel pump goes to a fuel filter assembly which is connected to a vaccuum line to the intake manifold. The discharge line is Teed and plumbed to the two carburetors. What is the purpose of the vaccuum line?


Thanks for any help I can get on this. Len

46HudsonPU

Welcome aboard Len - I am moving your thread to the 'Hudson' category, so it will get more views, and hopefully some assistance. 

Regards,

Park_W

Len, this sticking of the float/needle valve on these carb's is notorious.  You can fiddle around with float settings, but the sure-fire fix is to install a ball-type valve that is an invention of one of our Hudson Club members.  I have these in my Twin-H Hornet and have never had an overflow in the three years they.ve been installed.  Contact Bill Craig at scraig10@q.com.

Frankvintagefullflowcom

Len,
I have used Bill's "Craig Valves" as well and it appears to have eliminated the problem. They're a bit spendy but far cheaper than an engine fire. Depending on the overall condition of your carbs, you may want to get some rebuild kits and do a complete job, substituting the Craig units for the ones in the kit.
The additional line on the pump is the Vacuum booster for the windshield wipers. The pump is a double diaphragm type, an optional but common pump intended to aid in maintaining vacuum under low manifold vac conditions like accelerating or pulling hills. That's the way it was back in the day. It helped, but not much. I just don't drive in the rain.......works every time.
F

RonS

Len, the Craig valve eliminated the leak in my 53 as well. Also you can raise the PSI on the system and I found that I have no flooding issue even to 5.5. This will delay fuel starvation problems( vapor lock) a bit longer. Frank, I believe the dual diaphragm was standard on the hornet.

brumac

Len,  my carbs still had the old steel needle and were not the viton tipped variety, and the brass seat.   I used a small hammer to tap the bottom of the needle and formed a new seat.    It has been 4 years now and no leakage YET!      It has been in storage this winter so who knows what the spring and first start-up will bring?  Bruce

PAULARGETYPE

LEN YOU MAY HAVE TO REBUILD THE CARBS AS THE GASKETS MAY HAVE DRIED UP AND SRUNK UP A BIT IF YOU NEED KITS I HAVE THEM  IN STOCK AND THERE FRESH GASAHALL FRIENDLY KITS THAT IS THE FLOAT NEEDELE WILL NOT STICK CLOSED LET ME KNOW IF I CAN HELP IN ANY WAY 

Frankvintagefullflowcom

Someone will correct me if I'm full of it, but I hypothesize that the flooding wasn't as much of a problem (if at all) in the good ol' days before common use of Viton tipped needles. Although a great idea for most carbs, it seemed to have a detrimental effect on the WA-1s when the float chamber dries up far enough to drop the fuel level a bit (or more). When refilling the chamber at start-up, the float rises and pushes the needle up to the closed position.....but, the Viton tip would snag on the edge of the orifice in the brass seat due to slack in the bore. It didn't rise straight enough and so, left a path for leakage. A rap on the carb would shake it enough to make it go all the way in. The original steel needles have a steeper angle to the nose taper and are "slick" so they guide themselves right into the seat, as designed. This may be why brumac hasn't had the same experience as we who have gone "modern" with our Viton tipped inlet needles.
Sometimes better isn't.
F

RonS

I think you may be on to something, Frank. Years ago I switched to a Viton seat in , not only my Hornet, but my Model A as well. The Ford carb( Zenith), does the same thing with a gravity feed on occasions. If the car sits for a few days and I turn on the gas, many times fuel will run right out the vent hole, unless I tap the float bowl prior. The fuel evaporates, leaves a "sticky" coating on the Viton needle. The clean fuel will eventually dissolve the sticky coating, but by that time gas is all over the place. I do put a small loaf pan under the carb to catch the gas. Then, once running, I have no problems with leaks, even when parked with the gas valve open. I guess the WAs have a similar issue when the fuel pump ( either mech or electric) is operating. Any way, the Craig valve ( similar to Ford Gross Jet valves) cured the issue. Ron

Frankvintagefullflowcom

I developed that theory some time ago and modified one of the seats for the Viton tip ass'y by cutting a slight taper at the mouth of the inlet orifice, then lapping it with a steel rod having an end roughly at the angle of the Viton tip. The idea was to get the needle to guide itself into the seat without hanging up on the stock square edge. I did it to one of the two and found that it almost eliminated the problem......almost. Just when I though I'd cured it, it did it once again. In the meantime, the other carb had flooded many times.
I discussed the issue with Bill Craig and found that he'd arrived at the same conclusion, which, of course, is why he created the Craig Valve. Satisfied that I had identified the real problem, I caved and bought two of his valves. Glad he's got 'em.

Frank

RonS

Funny, I never had a leak in the front carb( twin H), only the rear.

[Deleted User]

Thanks to all of you for your replies to my problem I have emailed Bill Craig re his ball type valve availability.
It appears I did not explain the vacuum line on the fuel filter good enough. No it is not a vacuum line from the fuel pump to the intake manifold, I am well aware of the double diaphragm type fuel pumps. What there is on this engine is a glass bowl fuel filter mounted in the fuel line that goes from the fuel pump to the carburetors. On the top part of the filter is what looks like a diaphragm that is held to the filter with 4 screws. From this there is a line that goes to the intake manifold. This filter might not be a original part from Hudson. Could it be some thing that is suppose to prevent vapour lock?

Thanks Len

Frankvintagefullflowcom

Sorry about answering a question you didn't ask. That's the heck of trying to see things from this distance.

Hmmmm. I must admit that in my somewhat limited experience, I've not seen such a device. My wild guess: A vacuum operated valve that senses when the engine is running, the function of which would be to shut off the fuel line when the engine is stopped. The intent would be to prevent flooding after shut-down, as was sometimes a problem.

Just my guess. I'm sure others will have more.
F

RonS

Len, I picked up a part years ago. that sounds from what you described . It was a pressure regulator. I sold it since. It looked like a filter bowl , but it had a glass bottle threaded into the metal base. The glass "bottle" looked like a air brush paint "jar". Maybe that is what you have.

Frankvintagefullflowcom

"Regulator" was my knee-jerk guess at first but the vacuum connection to the manifold says otherwise. A diaphragm operated valve would be sensitive enough to react even to cranking speed manifold pressure drop. I think I'd eliminate it if that's what it is. Imagine the extra fuel entering the manifold in the event of a diaphragm rupture! I assume it's old and likely not friends with ethanol "enhanced" fuels.
Still hypothesizing,
F