I'm sure some of you have been following this on the 2A and NCFFC sites. But since it is a 3A motor I put in it is with a heavy heart and the humility that only a 65 year-old motor can bring to a man that I ask for your cumulative help. Hillbilly can verify what I have done to date. After the basic install I timed the motor using the GEICO method. After getting my new springs straight (Sharp eye there, BW.) I adjusted the valves on this 3A motor to 16, per the Rule of Nine. Two exhaust and one intake are used replacements as the ones in those positions had been worn by .008. I didn't lap them. I'm running 12V gear with a 12V generator, new unadjusted regulator and old starter solenoid. All connections are solid. Battery and motor are grounded to the frame. To date, I have been through two distributers, three coils, two resistors, three sets of points, countless condensers, a new set of Autolite 306 plugs, new wires and after Ohming them out, the old copper core are back on, a new cap (checked, no streaks inside), and three rotors. I've had four different carburetors and three filters on with no change in performance. I've adjusted and tested, adjusted and tested, and here is the result. When warm it will idle smoothly with an occasional hiccup. I drop it in first gear and off we go, grab second and Its OK up to about 30mph then the hiccups start, lower end of fourth and its ok but give it a little more gas and it bucks, snorts, stumbles, cuts out and in and I can't get above 40 mph. I'm near desperate at this point. I dread going in a third time. Help? Please?

I suspect a vacuum leak. They can do weird stuff to an engine. Spray around your intake with a can of starting fluid or the like and see if it picks up. I had a similar issue with my 225 V6. I rebuilt. Turned out to be a bad intake gasket. I didn't have a loss of power since it was only one cylinder. I would think this would have a bigger impact on the 134.

How is the compression of the engine? I had a 2A with horrible compression and that thing wouldn't get out of its own way.

Here is a real shot in the dark, how is your cam? The previous 225 I had threw an exhaust lobe and that caused it to spit back through the carb at high RPMs and did other weird things. It idled fine because it was opening just a hair, but not enough at high RPMs. Something like this on the 134 would do some very strange things because you only have 60 horses to begin with and when it is working hard, you definitely have a loss of power as you describe.

Scout...

The only time I had similar symptoms, it ended up being a fuel delivery issue.  It only acted that way when I was hard on the throttle, in 3rd, on a soft incline.  I was demanding more fuel than the system could deliver.  Fuel blockage.  Replaced my fuel filter and the hiccup went away.

That's the best I can offer.  You've done everything else...X4.

Tim

That compression sounds low, but that is what my '49 has about, 80 across the board.

On the fuel issue, my '49 had the needle seat in the carb keep on plugging up so very little fuel could get in. It did about the same thing as you describe too. Try replacing the fuel pump too with a brand new one. You said it was rebuilt several years ago. The one on my '49 started to go bad, and that caused problems. I replaced it, and they went away. The old one pumped, but not enough. This ethanol destroys the rubber. I've heard of the rebuild kits not being as great as a new pump for some reason. It could be that when the fuel pump sat dry, the ethanol screwed it up.

As Bob W said, hard to diagnose from a distance. You seem to have ruled out primary and secondary ignition systems with the components you have replaced. Fuel pressure seems OK, but need to double check volume as others have said. Have you installed a vacuum gauge? Look for the obvious, low vacuum or fluctuation under load. Could be a sticking valve, weak valve spring, worn cam as previously mentioned restricted exhaust system.  You have the basics of fuel, compression and spark but they need to be at the correct time. You seem sure that the timing is correct but do you have worn gears or chain? Just a few suggestions that come to mind.

You could try using a temporary electric fuel pump with a pressure regulator fed from a clean gas can. Run it directly to your carb and see if it makes a difference.