1929 Chrysler missing at higher RPM

The ongoing saga with my Orange 1929 has taken a new turn. After eliminating a defect condenser, a coil not able to take heat, a plugged pipe in the tank, an overhauled carb with two missing parts, an incorrectly put together vacuum-tank (my own fault) and several gas leaks the car now runs fairly well. and starts every time with a nice idle.

However at RPM above roughly 2500 the engine starts to miss and appear to run on 4 to 5 cylinders and there is almost like a engine speed limiter denying me getting above 40 MPH in top. Anyone got a clue for where to start looking on this issue, could it be electric or fuel related - or both? (The fuel consumption is also horrendous, like 5-6 mpg)

Just a thought if you have checked all the obvious things. If you can get a dwell meter somewhere check that. The points might be open a bit too far not letting the coil charge enough for proper spark. Or you might try closing the point gap just a little and see what happens. I don't know what the dwell meter should read.

Hi Narve,

Have you an owners' manual to reference? Under Engine Misses my Plymouth manual lists the following:

1. Broken or disconnected wiring

2. Fouled spark plugs

3. Spark plug gap improperly set

4. Loss of compression in any cylinder

5. Water in fuel

6. Overheating

7. Carburetor adjustment should be checked

99% of my engine problems have been fuel related and most of those have been the carburetor. I usually have to disassemble and clean all the jets. This carb is a Carter RT-08 and fairly simple with few adjustments that can be made.

You have a great looking car and need to get it reliable and on the road! Good luck!

frank

Hi Narve-Could be either fuel or electrical. Try running up the engine speed in your garage with a tachometer on the engine speed. If it doesn't begin to miss at up to 3,000 rpm then the problem might be fuel starvation and look to your vacuum tank fuel delivery to the vacuum tank from the gas tank. If it does then put an engine timing light on each spark plug wire in succession when the engine is missing. If you don't see a steady flash on 1 or 2 plug wires then you have a distributor to plug wire or point problems or a worn distributor shaft bushing..

If your don't have 19-20 inches of vacuum on the vacuum line running to the vacuum tank then you might not have enough suck to keep the tank level full.

The other problems involve point gap, condenser, and spark plug function. Don't rule out a bad plug.

You should always have 18-20 inches vacuum with a healthy engine which is properly timed. 20" is ideal. In your case good vacuum is critical for fuel delivery to the vacuum tank.

Marty Lum

1930 Desoto

The ongoing saga with my Orange 1929 has taken a new turn. After eliminating a defect condenser, a coil not able to take heat, a plugged pipe in the tank, an overhauled carb with two missing parts, an incorrectly put together vacuum-tank (my own fault) and several gas leaks the car now runs fairly well. and starts every time with a nice idle.

[ATTACH=CONFIG]204377[/ATTACH]

However at RPM above roughly 2500 the engine starts to miss and appear to run on 4 to 5 cylinders and there is almost like a engine speed limiter denying me getting above 40 MPH in top. Anyone got a clue for where to start looking on this issue, could it be electric or fuel related - or both? (The fuel consumption is also horrendous, like 5-6 mpg)

With such poor fuel consumption and inability to get beyond 40mph, I would be curious to see what state the plugs are in after you have experienced the missing episodes. If you are able to quickly shut it down having encountered the problem (dont let it idle) then pull the plugs, you may well find they are sooted up which obviously points to over fueling at higher throtlle settings. Even if the plugs are not sooted their colour may tell you something.

It sounds like it may be choked.

It sounds like it may be choked.

That was my thought.

That was my thought.

Great minds thinking alike.

Sooting might be a key-word here. I pulled the plugs and they all looked like this one:

After a round with wire-brush and sandpaper I put them back in and tried once again to set the carburetor according to the old Carter BB-1 receipt. It was however difficult to find an idle setting giving a peak vacuum reading (17-18" whatever I did), so I choose the lowest with a steady idle (1/2 turn out). I was also able to back off the high speed mixture setting from 1 2/3 turns to 5/6 turns roughly.

Then off for a test-run in the nice Norwegian summer night and hey, now 52 mph was obtainable before the pilot did run out of courage and no missing cylinders heard! Will have to test again tomorrow if the plugs again are sooting, and in a few days if the fuel consumption has normalized.

If the plugs are too cold as could be one cause for sooting, do anyone have recommendation for a higher heat range replacement?

Sooting might be a key-word here. I pulled the plugs and they all looked like this one:

[ATTACH=CONFIG]204838[/ATTACH]

After a round with wire-brush and sandpaper I put them back in and tried once again to set the carburetor according to the old Carter BB-1 receipt. It was however difficult to find an idle setting giving a peak vacuum reading (17-18" whatever I did), so I choose the lowest with a steady idle (1/2 turn out). I was also able to back off the high speed mixture setting from 1 2/3 turns to 5/6 turns roughly.

Then off for a test-run in the nice Norwegian summer night and hey, now 52 mph was obtainable before the pilot did run out of courage and no missing cylinders heard! Will have to test again tomorrow if the plugs again are sooting, and in a few days if the fuel consumption has normalized.

If the plugs are too cold as could be one cause for sooting, do anyone have recommendation for a higher heat range replacement?

Great progress, I would not mess with the hot / cold plug issue just yet as you have definitely made an improvement with your mixture settings by the sound of it.

As others have said it could be that the choke mechanism is at fault, however the fact that you had a good idle makes it unlikely; if it occurs again then its still worth checking that the choke is fully open.

You have made a rather large high speed mixture change so that may well be the root cause of your problem, and getting back to the plugs, if they look clean after your next run then leave well enough alone.

As to the vac reading, if you are really concerned then have another go at getting it up to about 18" - 20" after your run when the engine is at normal operating temps, not sure if you are aware but the timing will affect this setting also. If you cant achieve this number dont be too concerned particularly if you have an older engine, its more about getting the highest stable reading at idle.

So looks like you are heading in the right direction, keep us informed on your progress

I find that if plugs have been soaked in oil and gas they get a glaze that conducts electricity, and cannot be removed with a wire brush. The plug will misfire unless cleaned by sandblasting.

I have a small hand held blaster called a "spot blaster" used for doing small areas of rusty bodywork. It is like a small paint spray gun with a cloth bag to catch the used sand. It cost $12 at an auto flea market. If you can get one, and if you have a small air compressor they are a very handy thing to have.

Be sure to inspect the plugs carefully after sand blasting and use a needle to remove any bits of sand stuck between the insulator and shell.

Narve I had this problem, above 40 it would breakup stay at 40 or below it ran great, checked everything over and over to find everything was set right, what I found was the clip that holds the points down, was missing and one set of points would ride up the post, put the clip on and it ran great.

Narve I had this problem, above 40 it would breakup stay at 40 or below it ran great, checked everything over and over to find everything was set right, what I found was the clip that holds the points down, was missing and one set of points would ride up the post, put the clip on and it ran great.

Good point. I was working on a flatty recently that the owner had installed the points incorrectly. One of the pieces is a spring that pushes the points closed, he had it in the wrong position so at any speed that would be considered high RPM would float the points.