My 53 Hornet Won't start when its a warm day and the engine is warmed up. Please Help!

Rob Fayette

I have this great old 53 Hornet sedan and would like to drive it more in the nice weather but have never been able to because of this problem.

Here are the symptoms:

It always starts great when the engine is cold

If the engine is warmed up and it is a hot day, if I shut the engine off and immediately try to start it up again it starts up instantly

If the engine is warmed up and its a hot day, if I shut the engine off and wait a few minutes and try to start it up again it won't start. 

Fuel system set up:

Carter electric rotary fuel pump installed in fuel line back near gas tank

In line fuel filter between electric pump and gas tank

Stock combination mechanical fuel pump

WGD dual down draft carburetor

Original stock 308 engine in good condition. 64000 miles on car.

Hydramatic trans

A few years ago I was trying to figure out what was going on so I did a check that went like this:

It was a nice warm day (maybe 75 to 80 deg F, warm for washington state )

I took the car out for about a 20 mile drive on the freeway at about 70 mph

I brought it home, immediately shut the engine off, opened the hood, pulled off the air cleaner, and started looking down the throat of the carburetor.

At first nothing happened but I was determined to find something so I just kept watching.

I was timing it, and to my amazement, after 12 minutes I heard this faint squealing or hissing sound and about 30 seconds later 2 strong streams of gasoline started shooting out of the accelerator pump jets.  It shot out for what seemed like a long time as I remember.  Maybe 10 seconds or even longer maybe.

I have never been able to figure out what caused this or how to fix it.

Things I have thought it might be:

1. Heat soak is causing the fuel between the discharge of the mechanical fuel pump and the inlet needle valve in the carb to become so pressurized that it can push past the inlet needle ,totally fill the carb, push fuel into the engine and flood the engine.

2.  Heat soak is somehow causing the fuel in the carburetor to boil and that is causing fuel to be flooded into the engine

I know that the WGD carb has a different antipercolating system than the WA-1.

  The WA-1 has a "saxophone key" that vents the fuel bowl on the carb to atmosphere when the throttle is brought to idle position. 

 I can find very little info about the WGD antipercolating system.  In the 48-52 shop manual, on the specs page for the WGD, it has a notation that reads "Anti-percolating well; jet size No. 66 drill."

I wonder what the Anti-percolating well is and how it works.  Could it be that this system  has never really worked very well and could be causing the problem?

Last night I did some web surfing on WGD carbs and I found several cases where guys were having trouble with their WGDs starting well when engine was cold but not when it was hot.  They didn't really seem to find any solutions though.

Possible solution?:

If the problem were #1 above could I possibly solve it with a 3 port fuel filter downstream of the outlet of the mechanical fuel pump?  I have a setup like this on my pacemaker convertible.  The 3rd port on the fuel filter is smaller and you route a separate small fuel line from this port back to the gas tank.  This way you have a constant flow of fuel through the fuel system to help keep it cooler.  It also provides a way to bleed off the pressure that builds up between the mechanical pump and the carb due to heat soak when the hot engine is shut off. The 3 port fuel filter is what the AMC pacer used and is still available if I remember correctly.

What do you guys think?  Please help.  The old girl needs to be driven!

Park_W

I think you've nailed it with Cause #1 and the potential solution.  This is indeed a common problem.  To confirm it further, next time the occasion arises give it the tried and true treatment for a flooded engine:  accelerator to the floor, hold it there while you crank it.  It should start soon after a few revolutions.

TOM-WA-

ROB:

YOU MIGHT ALSO WANT TO TAKE A LOOK AT THE HEAT RISER IN THE EXHAUST MANIFOLD.

I HAD THE SAME EXACT ISSUES YOU DESCRIBED AND DISCOVERED THAT THE HEAT RISER WAS BROKEN AND THE HOT EXHAUST WOULD BOIL OR PERCOLATE THE GAS FROM THE OVER HEATED CARB.


EASY CHECK AND WHO KNOWS?..... MIGHT HELP COULDN'T HURT

onerare39

I think you are on the right track.

John Forkner

TwinH

To verify #1 throw an old sock with ice in it over the fuel pump after a hot shutdown. Should start easy if the pump (heat) is the source of the problem.

Jon B

The problem might be due to a "combination of ingredients", as opposed to just one cause.

For example, how many gaskets do you have under the carb?  I have four, plus the metal heat shield, then four more.  A lack of spacers might be one of several reasons that the carb is heating up.  And, together with some of the other potential problems, this might be causing your woes.

Rob Fayette

Thanks for the thoughts and tips.

I have checked the heat riser and it is working properly.  There is the proper number of gaskets and heat shield under the carb.

I am curious to find out how the anti percolator circuit works in the WGD carb.

I will have to try the ice test and see how it does.

I am thinking about putting the 3 port filter on after the fuel pump and running a line back to the gas tank.  I am thinking of tying in back at the tank ,by teeing  into the short piece of rubber hose that is part of the vent line. The vent line goes from the top of the tank to the fill pipe.  Where the vent line crosses above the frame rail it is rubber tubing.

Rob Fayette

Tim,

Thanks for your effort.  I read the write up at the link you sent.  The WDO carb, described at that web site, has a valve type anti percolator design.  The Hudson WGD carburetor doesn't use a valve.  Somehow it does the anti percolation without a valve but I don't know how it works.

Park_W

The '51 shop manual, WGD carb section, in the spec's makes reference to "Anti-percolating well; jet size No. 66 drill."  Maybe that'll give you a clue.  Couldn't find any other reference to that device.

Rob Fayette

Thanks for looking into this issue Park.  I noticed that same reference in the manual.  Somehow it seems there must be a circuit in the WGD that accomplishes the anti percolation without the use of any moving parts. Hopefully some carb guru will chime in at some point and shed more light on this.  The write up in the link that Tim ,(DocHubler) posted gives a really good description of what anti percolation is.  It says "The anti-percolator prevents bubbles of vapor from forcing gasoline out of the nozzle when a hot motor stops."   This seems like what could be happening with my Hudson.  I do feel though , that it is more likely  that its the pressurizing of the fuel line between the fuel pump and the carb.

[Deleted User]

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Rob Fayette

Sydd,  thanks for your input.  The wa-1 carter carb uses the saxophone key type anti-percolator so it doesn't really explain the carter wgd carb I'm trying to figure out.

  I
just found some info on this in a 55 motors manual.  First of all it says the WDO,WCD, and WGD carter carbs are very similar to each other; Then ,where it is talking
about WDO carbs, it says in part:
"Prior to 1939 these carburetors used valve type anti-percolators. During
1939 , also some models were equipped with an anti-percolator in the form of a
tube, Fig 1 WDO.

 

Here
hopefully will be a pic of Fig1  WDO I will try to upload to this thread:

 

Then a little further in the Carter Carb section of this Motors manual,when talking about the WCD carb  it says in part "The anti-percolator valves are not used.  A special series of vent passages in the high speed circuit act as the anti-percolator without the need for mechanical valves.

This info does help some but I still don't see how it works. lol

Rob

Hudson Grandpa

Rob:You didn't say that you have the gas line from the fuel pump to the carb covered. I took some rubber gas line, split it lengthwise and wrapped it around the line to insulate it. I did have a 2115S on the car, but after Methanol gas stuck the arm that goes to the jets, I bought a 776S from Al in Tucson, overhauled it with a Dayton Methanol kit. A real learning curve for me as I didn't know a carb from you know what. When I would go to the gas station and turn off the engine to install gas, the car would not start. 2115S.. Once you turn off that engine it becomes a blast furnace. I like the ice idea from Twin H. In the 40's & 50's we had to deal with hard starts, no starts, quick starts until 12 volts, Alternators, and the percolator problem was figured out. Even with the new carb & Ethanol kit, it's a guessing game to start. "Push the accel pedal once to set the choke". rr.rr.rr. nothing.. Oh Hold the pedal to the floor. Ok. rr.rr. rr.rr. Sit and wait a couple of minutes, hit the key, rr.rr.rr. bahroom....Whats the trick? Somebody let me know if they find it out, OK. And this with a 6 volt alternator, electronic ignition, twoOptima Batteries in Series, and a Starter overhauled and boosted to more cranking power. Plus a new carb overhauled with a new kit. Once started it runs fantastic...That's of course starting cold and above all owning a Hudson......

Rob Fayette

Thanks for your ideas Hudson Grandpa, no I don't have my gas line from the fuel pump to carb insulated; I may have to try that.

I think I have located the anti-percolater well that is referred on the WGD carb spec. page in the Hudson manual.

I think it is actually two wells with small holes venting them to atmosphere.  They are located about 1/2 to 3/4 inch before the end of the each  main jet . The small holes stick straight up and you can clearly see them when you open the choke plate wide open and look down into the carb.  The spec sheet says they are drill size #66 and sure enough when I put a #66 drill into the holes it just fit.  A #65 bit was too large to fit so I am pretty sure this is the holes they are talking about.  I wish I could find a drawing that shows the internals of the WGD carb but I'm not sure one exists.

Here is a pic looking down into the throat of a WGD carb.  The two wells are at the bottom side of the opening in the pic.  One on each side of the accelerator pump jets. ( I was trying to modify the picture showing the parts identified with arrows but I wasn't successful.  I was trying to use Microsoft word to do it but I couldn't attach the completed Word document) 

Park_W

By George, I think you've got it !!

befishers1

Thanks for the post, having the same issue and Walt pointed me to the anti-percolation idea. I found this link for the inside of the WGD, choose the 6b download page 4.

www.pontiacsafari.com/55/shopmanual

Rob Fayette

Thanks befishers1, it's great to finally see a an internal view sketch of what the anti-percolating circuit on a WGD carb actually looks like.  I think I will try to take a pic of the sketch and post it here to help with the continuity of this thread.

Since I last posted to this thread I have installed the 3 port fuel filter with the 3rd port going back to the gas tank.  At first this seemed to cause more problems .  Now when I took the car out onto the freeway and accelerated hard the engine would cut out.  It was like the new bypass line going back to the tank was taking so much fuel that the mechanical fuel pump couldn't supply both it and the carburetor.

I ended up doing 2 more things and so far it seems to be working with no flooding problems with the hot engine and no cutting out on acceleration.

This is what I did:

1.  I took a 5/8 inch long piece of 1/4" diameter steel rod.   I then drilled a 3/32 inch through hole in the center of the end of the rod.  I used this as a restriction in the line going back to the fuel tank from the 3rd port of the fuel filter.  Since the 3 port fuel filter is installed with short lengths of rubber fuel line and hose clamps I just inserted the restrictor in the the middle of the short rubber fuel line that connects the 3rd port of the  filter to the fuel line that goes back to the fuel tank.  This restrictor reduces the amount of flow going back to the tank.

2. I had learned from guys on this forum that sometimes you need to have a bypass check valve installed around the Carter Electric Rotary Vane fuel pump.  This check valve is used to reduce the restriction that is created when the electric fuel pump isn't in use.  I was still having trouble so I added this check valve.

I found a great check valve on ebay.  It takes very little pressure to open it and it can handle a good volume of flow.  I used the 8mm size for 5/16" fuel line.  Here is the link to it on Ebay http://www.ebay.com/itm/390801413623?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT

There is also something that I forgot to mention that I should probably have mentioned much earlier in this thread :  Back when I was checking the size of the anti-peroclating ports with the #66 sized drill bit I found that one of the anti-percolating ports was at least partially plugged .  It was probably old gasoline residue that had built up over the many years.  I also think  that when someone boils out one of these carbs during a rebuild it probably makes these antipercolating ports even more plugged.  This could be a significant part of what is going with these wgd carburetors.

I have driven the Hudson a few times this summer on pretty warm days with no problems.

Rob

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