Holley Model 59 Diagnosis

Joe KCMO

Joe KCMO

Senior Member
I have a Holley Model 59 mounted on a stock rebuilt 1939 Ford engine. I am having difficulty making the engine idol and accelerate without an occasional backfire. The engine has a stock helmet distributor with points set to 0.16". Top three questions for me?

1. I cannot get to idle slow. Idle screws all the way in do not make much difference for adjusting idle.

2. Is 0.16" optimum for points.

3. For this motor which is the better carburetor 91-99 or a model 59?

Help with any of these would be appreciated. I gave up on searching, sorry.
 
Hi Joe. Last question first, the 91-99 is the correct carb for your car, but the only difference between it and the moel 59 carb is the controls. If you have throttle and choke hooked up, you're good to go.

.016" points is only part of the ignition story. Timing and dwell are each as important as point gap. Tell us how you set up your distributor for advice on that unit.

Idle screws all the way closed indicates a blown or otherwise compromised power valve. Removce the carb from its base, then remove the power valve for testing. As you remove it, note if it was tight, and if the gasket has been effective. new power valves may have a radius on the inner gasket surface that doesn't match up with the flat surface of the carburetor. If this is the case, that issue must be addressed. Now to test the power valve, place it between your lips as you would a whistle, and suck on it to draw a vaccuum to hold your tongue. If that doesn't work, try the opposite direction. One side should hold vaccuum against your tongue, if not, it is garbage and must be replaced.

Let us know how you do.
 
ford38v8 said:
Hi Joe. Last question first, the 91-99 is the correct carb for your car, but the only difference between it and the moel 59 carb is the controls. If you have throttle and choke hooked up, you're good to go.

.016" points is only part of the ignition story. Timing and dwell are each as important as point gap. Tell us how you set up your distributor for advice on that unit.

Idle screws all the way closed indicates a blown or otherwise compromised power valve. Removce the carb from its base, then remove the power valve for testing. As you remove it, note if it was tight, and if the gasket has been effective. new power valves may have a radius on the inner gasket surface that doesn't match up with the flat surface of the carburetor. If this is the case, that issue must be addressed. Now to test the power valve, place it between your lips as you would a whistle, and suck on it to draw a vaccuum to hold your tongue. If that doesn't work, try the opposite direction. One side should hold vaccuum against your tongue, if not, it is garbage and must be replaced.

Let us know how you do.
Click to expand...

Good call on the PV.
 
My car is driven at sea level 33' above. What would be the recommended power valve and jets for the Model 59.
 
I just took out the main jets and they are 51"s. I did find the markings on the PV which were 7.5 and seems to be alright, holds a vacuum with my tongue. Could it still be bad?
 
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Joe, the valve holds to your tongue, but it must also be installed with care to be sure that it will maintain vaccuum. Check the gasket and its relationship to the carb body, and just as important, the gasket between the carb body and the base. It is important to know that the PV will not function correctly if these gaskets are not sealed perfectly.

Apparently, the pv chamber has a vaccuum leak around a gasket, which opens the PV to bring in fuel to the engine, a good thing when at speed, but not good at idle. That's why the idle screws can not shut down the engine when fully closed.
 
What I did find so far is that the float needed adjustment. Also when I close the left mixture screw the engine stalls, not the right one. Getting closer I think.

I noted on my carburetor has a hole in the carburetor power valve chamber. I assume this is where the power valve gets its vacuum. My intake manifold (aluminum) does not have the matching hole. I am wondering if the power valve does not get any vacuum. Can I drill a hole in the manifold? What are the symptoms of no power valve action at all? Thank again.
 
The hole in the vacuum chamber goes straight down and branches off to each bore in the base. If the base is upside down, you will see it.
 
I see some intake manifolds have a separate hole for vacuum on he mounting surface while others do not. Does this make a difference?
 
Joe KCMO said:
I see some intake manifolds have a separate hole for vacuum on he mounting surface while others do not. Does this make a difference?
Click to expand...


I think those holes were for heat, and used with the Strombergs. If you have a manifold with this hole, and use a Holley, I think you would want to plug it.
 
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Thank you, 1952Henry, I think I have my carburetor under control and know a lot more about it. Now on to the ignition.
 
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