59 A/B surges at speed

Walton Feep

Walton Feep

Member
Hello folks!

I have a lot to learn about my early Ford V8 so please excuse my novice questions.

I purchased a 1941 Super Deluxe over the summer. It is a solid enough car, complete and, after some extensive mechanical work, drivable. It has a replacement 59 A/B.

I had extensive work done to it at a local shop - new carb, entire fuel system was replaced including the pump and tank and a pressure regulator was installed. They rebuilt the brake system, did suspension work, and replaced plugs, wires, points, caps, rotor, capacitor and coil. It runs, shifts and stops well but for one issue. After a few minutes driving the engine seems to start "surging". It isn't effecting drivability and it will still idle fine at stops. But I am just not confident that this is "normal".

I am wondering if I am just holding it too long in 2nd gear as when I upshift it seems to be better. I have had no experience with a car like this before so I am not sure what is normal.

The temperature gauge indicates the cool side of "normal". I do intend on calling the shop that did the work about it next week.

Any ideas on a place to start? Temp? Timing? Fuel supply?

Thanks in advance!

Feep
 
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Likeliest cause...slightly lean.
Quick test for that...while driving along in surge mode, slowly pull out the choke and see if it improves things...
If it does prove lean, there are multiple causes, mostly simple, and we can put together a diagnostc attack.
Air leak, wrong jets, restriction or pup problem in fuel delivery, bad regulator...
Upshift slows down engine, cutting demand slightly and possibly suggesting that problem is in fuel system and not carb.
 
Thanks Bruce! I think the choke does have an impact but I will test this weekend if the weather cooperates and get back to you.
 
If it idles good - (You are on the idle jets)

If it accelerates strong - ( You are on the accelerator pump and power valve)

If it surges/stumbles running along at the same speed - (You are on the main jets)

I vote for dirt in the main jets. I would take the top off the carb, look for dirt in the bowl and remove and blow out the main jets. Also report on their size.

Is your gas supply clean?

John
 
John,

The carb is brand new as are the fuel lines, pump, regulator and tank. Obviously the fuel is new too!

Thanks!

Feep
 
The shop that did the work did put a Mr. Gasket Fuel Regulator on the car when they replaced the fuel pump and carb. I now have learned that these regulators are very unreliable and will ask them to replace it. In the mean time, I could adjust the regulator to increase PSI and see if that fixes the surging. It is set at 2.5 but I don't have a gauge so don't know how accurate it is. Any thoughts?
 
Personaly I think 2.5 is a tickle low on a 94. Iv'e had to much advance give a serge at cruise.
What pump was installed? I'm sure that some of the regulator setups do drop the pump psi but also impede good flow of fuel. This is why I like the idea of a sized return fuel line rather than regulator with a lectric pump. Havent yet tryed to build one as don't have the need at the moment.
Keep us posted.
Good luck.
Martin.
 
I am with the blocked jets boys .Get ride of the regulator and rebuild a stock pump ,2.5 PSI is the minimum needed according to A/C
 

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I had the same problem and backed off on the pressure regulator and it smoothed out. You might want to try that?
 
Ask your rebuilder what size the carburetor jets are. They may be sized as if it were to be installed in a multi-carb setup. Depending on your elevation, you need .050 or .051 jets.
 
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Thanks all. I will call the restorer on Tuesday as there are a few things to talk about. The carb is a new Holly 94 (Made in USA tag and stamped "H" and "94"). The pump is new too. They initially had an issue with the motor surging after they replaced the carb which is why they put the regulator on. Maybe they need to check the size of the jets. I don't want to take it apart myself because then they will be off the hook on making it right.
 
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Thxs Walton - but I can't take credit for her, my Grandpa hopped her up right before and just after WWII , but she is a treat.
Btw good choice of Ford yourself!
 
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