williambillig

I have a 1934 Plymouth PE Sedan. It has a '34 flathead 6. Last year, I began having starting and running problems. Since the engine is relatively simple, I have tried to determine the possible problem. I have rebuilt the carburetor, the plugs, wires, condensor, points, cap and coil. After none of these changed the performance, I took a look at the timing chain. It was loose, so I got a new one and also replaced the crank gear. The cam gear didn't look bad, so I didn't change it.

Well, after all of this, it starts but misses, backfires, and is not generally road-worthy. The other night, a friend and I waited until dark to see if we could see any arcing. Didn't see anything.

I am not much of a mechanic and don't know where to go next. Anyone have any other ideas?

Bill

67 GTX

Does the car run worse once it heats up?
Have you checked for any vacuum leaks?

williambillig

Thanks for your reply. It doesn't seem to make a difference whether it's hot or cold. In order to get it hot, I have to play with the choke and accelerator. I have looked for vaccum leaks. Located a potential but it didn't seem to make a difference. An special locations you would suggest for vacuum problems?

Bill

78doubleR

are you sure you put the tchain on right and that the motor stayed in time? sounds like its out of time to me.

67 GTX

Carb. to manifold is the spot that jumps out to me the most.

cbroeders

sounds like a timing issue to me as well

440roadrunner

My old Motor's Manual, which covers 35/ newer, shows a fairly common "dot to dot" alignment of the timing drive, you you recall any troubles there?

Also the tuneup guide shows the following:

35-40, intake valve opens 6* ATDC, exhaust valve closes 8* ATDC

They show operating clearance, .006H for intake, .008H for exhaust

Tuneup for 35-38 engines, shows a plug gap of only .025

Breaker gap .020, dwell angle 35-38*,

timing "fourth line after "DC or "0" mark on crankshaft pulley.

Positive ground.

Unless you recall being fuzzy on the cam drive, I'd suspect ignition and carb/ vacuum leaks.

Leave no stone unturned. You can squirt about anything, including water, around the various connections on the intake manifold, the carb base, etc to look for vacuum leaks.

I would not assume ANYTHING about ignition. Could be a bad ground, for example, at the breaker plate in the distributor.

A "new" condenser does not mean a "good" condenser.

Suspect the coil.

Check all the high tension wires, and measure coil operating voltage at the coil "hot" terminal.

How about wear in the distributor?

Find a buddy with an old tune up machine, or even and astute electronics experimenter or amateur radio operator who has AND KNOWS HOW TO USE an oscilloscope.

What does the spark look like?

Does it seem to be one or two specific cylinders, or "erratic?"

You can do a quick and dirty cylinder balance, or load test, by rigging a probe (like your 12V test lamp) and ground one plug at a time. The engine should drop equally and "sound the same" on each cylinder as you short one plug at a time.

Coronet 500

I would do a compression test and look carefully at the distributor bearings for wear. Mounting it say in a vice and use a dial indicator on the top and bottom will be more work but a for sure answer.

williambillig

I've got it running, however, it won't run smoothly unless it is 1/2 or more choked. The timing is set correctly. The wires are good. I have not located any leaks and don't believe there are any. Any more thoughts. Don't think it is electrical...this it is gas. Tried a '33 carb that I know is in good shape. Runs the same as with the '34 carb. Any further help? Appreciate any ideas.

Bill

440roadrunner

If you have to choke it, it's most certainly either a carb problem or vacuum leak.

What did you use to try and locate the leak?

Does the idle mixture screw have "good effect?"

TVLynn

Have you done a compression test ? How much vacuum at idle ?

pitbull

you can spray carb cleaner or brake cleaner around the intake & vaccum lines to check for vacuum leaks..just be sure the area isnt to hot it will light up....if the engine picks up or stumble you have found it... but I would run a compression test ..them maybe a leak down test... have you checked plugs,wires,dist cap.ect?