1927 Dodge Brothers Four Screen

Hello all! Quick question and help on a small problem.

Our Four Screen seems to be having a problem missing and back firing. Not real bad, but especially when first starting up and driving it. We have done a complete tune-up, changed everything, plugs, points condenser, adjusted the timing, new plug wires etc, etc. and the problem seems to persist. Not sure of the point adjustment, since the manual shows more than one for that era.

The drive train, according to the numbers was assembled in 1926, but the truck came off the assembly line in Oct of 1927. Any ideas or help would be appreciated.

Thanks.

Backfiring is often caused by a lean fuel condition.

Backfiring is often caused by a lean fuel condition.

Is there a quick fix? we have tried adjusting the timing and can't seem to find the proper setting. Still missing and back firing. We have the distributer adjustment lever locked down ad can't adjust from the steering column anymore.

I don't know of a quick fix for lean other than taking the carburetor apart and looking at the jets and such.

One may check the filters and supply line to see if there may be air entering the system.

From your description it would seem that you should have enough spark.

Sounds like bad gas, to me.

Sorry for asking what to some will seem an obvious question but when you say "backfiring" do you mean "popping" in the carb? or explosion occurring in the exhaust?

Ray.

By definition I would say that backfiring would be back thru the carb. Although I have heard explosions thru the tail pipe called backfiring as well. Thru the exhaust would be different problem than running lean.

This problem could be a points adjustment, however it was implied that this was addressed already.

Any cracks in your distributor housing?

By definition I would say that backfiring would be back thru the carb. Although I have heard explosions thru the tail pipe called backfiring as well. Thru the exhaust would be different problem than running lean.

This problem could be a points adjustment, however it was implied that this was addressed already.

Thanks Jack. I have heard people say they thought it was a car "backfiring" in the exhaust when they have in fact heard a gunshot. I am in full agreement with you that by definition a true backfire noise would be coming from the carb and imply a lean mixture or a timing issue. I have to admit being guilty of misusing the term myself in the past and causing some confusion. Hence my question. My apologies.:mad:

Here's a good discussion on the difference between "backfire" and "afterfire" and several of their potential causes:

http://en.wikipedia.org/wiki/Back-fire

Here's a good discussion on the difference between "backfire" and "afterfire" and several of their potential causes:

http://en.wikipedia.org/wiki/Back-fire

That is a good explanation Phil.

Sounds like bad gas, to me.

Me too.

Sorry for asking what to some will seem an obvious question but when you say "backfiring" do you mean "popping" in the carb? or explosion occurring in the exhaust?

Ray.

It's backfiring thru the muffler / exhaust. Loud bangs. Don't think we have a cracked Distributor and as for dirty gas, I don't know. Have not changed the fuel or checked the tank for some time (since it was restored, 25 years ago). Don't have any filters in the gas line, that I know of, but will check.

I think we will try Electronic Ignition. The mechanic seems to think that this may take care of the problem. I'll mention the gas lines and dirty gas to them.

I would be sure the gas was fresh before spending cash on fancy electronics. It's more than likely your gas has gone off.

If the problem persists with fresh gas you might have a problem with the vacuum tank. On my car (same year as yours) fuel was being drawn down the vacuum line due to a faulty valve in the top. This problem was temporarily solved by fitting an electric fuel pump.

In my opinion, the chances are that your problem is just bad gas.

Ray.

Your mechanic or restorer should have installed at least two filters. Not so much for when the restoration was done (except for any residuals in the system) but for now, 25 years later.

You may have some junk in the carburetor causing problems. But if it is coming from the exhaust I would be more inclined to check ignition. If the engine turns without spark and gets fuel in the exhaust then gets spark again it would cause what you are describing.

When I was a kid I remember turning the ignition off and pumping the throttle going down a hill. When I turned the key back on I would get a big explosion (that ultimately cost me a muffler). Same theory of the flame throwers that the rodders use today.

Is there a quick fix? we have tried adjusting the timing and can't seem to find the proper setting. Still missing and back firing. We have the distributer adjustment lever locked down ad can't adjust from the steering column anymore.

You need to be able to use the steering wheel adjuster to advance and retard the ignition. If the engine starts easily the timing is likely sufficiently retarded for starting. You will then need to advance the ignition when on the move to get the best from the car. Failure to advance the timing manually at speed can cause overheating and eventual exhaust valve failure.

There is a degree of automatic adjustment by spring controlled centrifugal bob weights within the distributor but further manual adjustment is provided for. This extra adjustment would normally be taken care of automatically by vacuum control in a later system. As you know, an electronic system could be used to obtain more accuracy, however no system can fully compensate for a worn distributor or backlash in the drive gear.

Ray.