Car doesn't want to run after carb rebuild

[Charlie ny]

Ralph,
It sure seems like there's a couple things not happy with your carb. 94's are
very sensitive to vacuum leaks especially between the base and bowl AND excessive
clearance between the base an throttle shaft. From bitter experience I have found
the most reliable source for power valves is Daytona parts. This is only my opinion
but I would establish for sure your pump puts out no more than 2 1/2 psi. I'd obtain
a Daytona 6.5 power valve and while I was waiting for the power valve to arrive I'd

make sure there was no more than .0035 clearance between the throttle shaft and

the base....if more I'd fit an oversize shaft. Lastly establish that the bottom face

of the bowl is flat. Every 94 I build requires some degree of machine work on the bottom face of the bowl. It is not uncommon to find that face twisted or warped
.015 or more out of flat. Again this is only my opinion, I certainly respect any and all other opinions.
Charlie ny

[flatjack9]

Originally Posted by fortyfords

I thought 42 Merc engines ran a Stromberg 48 carb? Once you get it running, unhook the vacuum hose to the wiper motor, hook up a vacuum gauge to the fitting where the wiper hose was and set the idle screws to get the highest vacuum reading for each one, then the idle screws are set correctly. This isn't your problem but needs to be done when you get the rich mixture figured out as everyone suggested.

42 Mercs used a Holley 94 marked 21/29.

[Ralph S.]

Ford38v8
Following advice from here I did get a new machined power valve from Vintage Speed along with a proper gasket. That was one of the first things I went with. At this point I'm thinking it's the fuel pump pushing too much fuel in, overpowering the needle valve and the float. May be why I see little bit of fuel leaking out of the top of the carb. Now I just have to find a proper fuel pump, somewhere other than Mac's.
@Fortyfords
Originally my wife's grandfather built the car with a Ford motor, later on I think the block developed a crack. He found this Merc motor and swapped it out using most of the parts from the original motor including the carb.

[Ralph S.]

As far as fuel pumps go. Does anyone know where I can get one that will work like it's suppose to? Or someone that properly rebuilds them.

[ford38v8]

Originally Posted by Ralph S.

As far as fuel pumps go. Does anyone know where I can get one that will work like it's suppose to? Or someone that properly rebuilds them.

Ralph, if gas is leaking out the top of your carb, then yes, it may be coming from a pump delivering too much pressure. If you still have the old pump, dismantle it to salvage the spring, and swap the old spring for the new one in the MACS pump. New pumps are known to have high pressure due to springs being too strong.

[Charlie ny]

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I can certainly supply you with a rebuilt and tested fuel pump if the suggested spring

swap does not work out. My pumps are ethanol proof, e mail me if you wish.
Charlie ny
[email protected]

[Ralph S.]

@Charlie NY


Email sent

[fortyfords]

Originally Posted by flatjack9

42 Mercs used a Holley 94 marked 21/29.

You are correct, I read that but hated to believe it when there was a Stromberg 48 on my engine, Thanks

[cajunfirehawk]

Interested to hear the outcome...

[Charlie ny]

Guys,
Ralph is sending me his original pump and the Mac's pump and I hope his
carb. I have assured Ralph that when his parts arrive I'll get on them pronto. I will
repair/rebuild as required and get the parts back to him as quick as possible. He and
I will keep everyone posted on how things work out.
I do hope this thread remains on page one.
Charlie ny

[grumppyoldman]

My 41 did not run smooth before rebuild of carb. installed a Mr. Gasket fuel regulator and pressure gauge down stream of regulator. Set pressure at 2 1/2 # and runs great, problem solved. BTW the regulator will not work by it's self, the markings on it are way off. That's why I use a pressure gauge ahead of carb. Al

[deuce_roadster]

Have you determined that the float level is correct and that the float itself infact floats and does not bind up? Bad needle or seat and or bad float could be also causing this over rich problem.

[Ralph S.]

@ deuce roadster

Checked and tested the float, it's operation and setting. I'm fairly confident it was the pump pushing too much pressure. Charlie NY will be doing his magic on my pumps. I'm fairly confident the issue will be corrected once I get the pumps back. I will post an update once fixed.

[Flathead Fever]

You will need to adjust the air fuel mixture once you get the correct fuel delivery and float leavel. When it was running rich I did not see you mention that you tried turning the air fuel mixtures screws in all the way (gently seat them). That should completely shut off the fuel at idle. If it doesn't, your getting fuel from another source.. Once you have the correct float level and fuel pump pressure you will need to adjust the fuel mixture at idle. Turn both screws in until they "gently" bottom out and back them out 1 1/2 turns. Start the engine. The goal is to turn the screws to achieve the highest possible idle. You must turn both screws the same amount to "balance" the carbureto . You can try a 1 /4 turn at a time. Turn them both in a 1/4 turn at a time until the idle starts to drop. Then back them off a 1/4 turn at a time until it reaches its fastest idle. Now your getting pretty close. Set your idle speed with the idle adjustment screw. Now take one of those small propane bottles and pass it over the carb, or give it a very small shot of starting fluid . If the idle goes up your set to the lean side and you need to back the air fuel mixtures screws out another 1/8 to a 1/4 turn at a time. You keep going back and forth until the propane does not have any effect on it. If you give it propane and the idle drops the engine is already getting too much fuel. Turn the screws in a little at a time. When the mixture starts to go lean again adding propane will make the idle go up. Then you back the screws out until the propane does not have any effect it. It helps to bottom out the air fuel mixture screws and then make a little white dot at the top of the screw heads, to help count the turns evenly. You get to be a master at this you can move on to choosing correct size power valves and main jets.

A carburetor will never operate the same two days in a row because of barometric pressure changes. Most of the time you will never even notice it. Every once in a while your car will fill slightly sluggish or it seems like its running better. You almost chock it up to your imagination. Sometimes it is the weather affecting the carburetor. Its always a good idea to set the air fuel ratio just slightly to the rich side for better all around driving. Its better too run the engine "slightly" rich than it is lean.

[Flathead Fever]

Originally Posted by Ralph S.

@ deuce roadster

Checked and tested the float, it's operation and setting. I'm fairly confident it was the pump pushing too much pressure. Charlie NY will be doing his magic on my pumps. I'm fairly confident the issue will be corrected once I get the pumps back. I will post an update once fixed.

If its pumping too much fuel, with the air cleaner removed and engine running you should see fuel overflowing into the venturi from the float bowl vent. You might wear goggles for this. Its designed like this on purpose so if the float bowl overfills it floods out the engine and it quits running. Better that the engine quits than if it overflows all over the outside of your engine and those arcing cloth covered plug wires burn your car to the ground while the engine continues to pump even more fuel onto the fire.

[Charlie ny]

Guys,
The fuel pumps arrived @ 6pm today, Thurs 1/24. Both are off shore made.
The older of the two was jammed up solid.....diaphragm hard as a rock. The newer
pump ( last one on Ralph's motor ) put out slightly less than 3 psi.....so......I hope

to get the carb soon.

Charlie ny

[Blastfromthepast]

I had this problem once. What happened after I rebuilt the carb the float wasn’t pushing the needle against the seat and was actually flooding the carb. When you take it apart again check waythe needle connects to the float. Pick the float up to where it hits the needle against the seat. See if the tab hitting the needle is to low. This would cause more gas to enter the carb and flood it making it to rich.

[Charlie ny]

Guys,
I'm sending 2 pumps back to Ralph as soon as they air out....either Sat morning or Monday AM. I installed my own diaphragms in both and each tested slightly less than 3 psi. As promised I freshened one of his China pumps & I rebuilt a second pump using a USA core with the pet cock and replaceable phenolic valves. No carb yet, that will be down the road perhaps.
Charlie ny7

[Flathead Fever]

Originally Posted by Blastfromthepast

I had this problem once. What happened after I rebuilt the carb the float wasn’t pushing the needle against the seat and was actually flooding the carb. When you take it apart again check waythe needle connects to the float. Pick the float up to where it hits the needle against the seat. See if the tab hitting the needle is to low. This would cause more gas to enter the carb and flood it making it to rich.

Any time you rebuild a carb before you install it blow into the fuel inlet with your mouth to make sure fuel will flow through the needle and seat. As your blowing on it flip the carb upside down and the float should shut the needle and seat and you won't be able blow through it. I di this on every carb I rebuilt at work.

Also when you remove a carb that you suspect has a needle and seat problem blow into it before you disassemble it to verify if the needle and seat are working properly. I suggest draining the fuel out of the carb first otherwise don't be blowing out any birthday candles for at least a day.

Never blow air from a compressor through the needle and seat or anywhere else that leads into the float bowl while the carb is assembled I did it once on the carb on my 8N Ford tractor. The 120 lbs. of air pressure going inside the float bowl crushed the brass float as flat as if you had hit it with a sledge hammer.

[mike42]

Ralph ………..we’re you able to resolve your issue here. I have the same one with my ‘40 94 Carb.

Thx…..Mike