Jerky Runner

I had a similar problem on one of mine (was not running smoothly), but was not backfiring. I tried a number of things, and what finely worked for me was to reset the valve clearance on all the valves.
 
Ben, this also could be my problem. I did try to adjust the valves awhile back. But I was having a problem with one of the adjustable valves and I may have messed it up. So I may need to try adjusting them again.
 
BILL WILLIAMSON said:
I once saw some "JERKY RUNNERS", while running, they were talkin' to one another, on their CELL PHONES!
Bill Babble
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I see them (cell phones) in my living room. They aren't jerky in their actions but they are "Jerks". Forgot how to communicate in this environment.
 
Well back in Aug of 2018, I started this post about my jerky 29 coupe. Guess what, here it is Sept 2019 and I have the same problem. Same situation, ran it is 4th of July parade, let it set until now (sept) and the same problem started again. The problem was that when I would start to go, press on the gas it would jerk and backfire in the carb.


So I did some thinking about the situation as to what it was doing--- would "miss" when pressing on the gas starting out from a stop. Well so many people recommended Marvel Mystery Oil so I got carried away. A few days ago I took the plugs out, dumped in a bunch of MMO in each cylinder, and let it set for a few days. Today I got in it, started it up(and it did start) and I had a concern that the neighbors would call the fire department. So I backed outside and let it run for awhile blowing smoke all over the neighborhood. Then I got in it and drove it around the block a few times in 1st and 2nd. At first it still had the problem. Then after a few rounds it all cleared up-smoke and the jerk (not me).

After parking it after a few miles, I turned it off and let it set for while. They I tried to start it. I had spark up, gas lever up and just a touch of the starter, it was up and running! Wow! This start was better that it had done for years. I also pulled one of the spark plugs and looked at it. Before the MMO, when I took them out they were covered with black junk. This time the electro look nice and brown and no black stuff.


Anyway to sum up all these comments- it does look like I had a stuck valve. Putting the MMO in the cylinders and running it after that did clear up the problem of a jerky start where it would jerk and backfire in the carb.


Hope this helps someone.
 
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Thanks for the come back and final report. MMO seems to be a common cure and should always be the first step in solving performance problems. Go drive it like you stole it !!
 
Glad it worked out for you Fred. :) This tells me that you need to start looking for more parades during the year. :D And for what it is worth, i always add about 4 oz of MMO every time i fill up on both of my A's. Mark.
 
zzlegend said:
Glad it worked out for you Fred. :) This tells me that you need to start looking for more parades during the year. :D And for what it is worth, i always add about 4 oz of MMO every time i fill up on both of my A's. Mark.
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Mark, the MMO idea sounds good. Will have to do. But I think the parades may go. Hard on the old rig, clutch etc. So think I will watch parades instead of being in them!
 
Fred K-OR said:
Mark, the MMO idea sounds good. Will have to do. But I think the parades may go. Hard on the old rig, clutch etc. So think I will watch parades instead of being in them!
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I am with you on that Fred. I use to do two different Christmas parades for a few years, but now i find a fold out chair and a cup of coffee just seems to fit me better. ;) Mark.
 
Fred K-OR said:
Well back in Aug of 2018, I started this post about my jerky 29 coupe. Guess what, here it is Sept 2019 and I have the same problem. Same situation, ran it is 4th of July parade, let it set until now (sept) and the same problem started again. The problem was that when I would start to go, press on the gas it would jerk and backfire in the carb.


So I did some thinking about the situation as to what it was doing--- would "miss" when pressing on the gas starting out from a stop. Well so many people recommended Marvel Mystery Oil so I got carried away. A few days ago I took the plugs out, dumped in a bunch of MMO in each cylinder, and let it set for a few days. Today I got in it, started it up(and it did start) and I had a concern that the neighbors would call the fire department. So I backed outside and let it run for awhile blowing smoke all over the neighborhood. Then I got in it and drove it around the block a few times in 1st and 2nd. At first it still had the problem. Then after a few rounds it all cleared up-smoke and the jerk (not me).

After parking it after a few miles, I turned it off and let it set for while. They I tried to start it. I had spark up, gas lever up and just a touch of the starter, it was up and running! Wow! This start was better that it had done for years. I also pulled one of the spark plugs and looked at it. Before the MMO, when I took them out they were covered with black junk. This time the electro look nice and brown and no black stuff.


Anyway to sum up all these comments- it does look like I had a stuck valve. Putting the MMO in the cylinders and running it after that did clear up the problem of a jerky start where it would jerk and backfire in the carb.


Hope this helps someone.
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I also think I need to change the engine oil after this situation because I did put a liberal amount of MMO in the spark holes. I am sure a lot of it got in the engine oil. Maybe that is good for the oil but it is about time to change the engine oil anyway.
 
Is the ignition cable an original one ? I had a very similar experience recently with my car, and finally diagnosed the problem as an intermittent short inside the cable conduit. the wire inside was almost 90 years old and the insulation was badly cracked and falling off. Found this only after rebuilding the distributor and replacing the coil.....all the parts I replaced were working just find. Checking the ignition cable never occurred to me.
 
Well I took the old jerky runner out for a drive today. About 2 weeks after the MMO treatment in the cylinders. It started better than it ever did, after warming up (46 degrees around here today) and ran like it should. No jerks and good pickup. So I again would guess that I had a stuck valve or it may have be very sooty spark plugs that cleared up with the MMO. But I am no experts on this type of thing but this is what it seemed like to me.
 
Good to hear Fred. Depending on the weather, you just might have to get it out and drive it a little more often. Take the wife out to breakfast or lunch or dinner. Or maybe all three. :) Good luck with it and have a great weekend. Mark.
 
The two most common problems that can happen after a car sets for a time is fuel deterioration and sticking valves.

Fuel doesn't last very long unless it is a higher quality formula like 93 octane premium. Avgas last a lot longer but it's overkill on a model A and it's not legal to run it in cars. Draining the fuel is a PITA but sometimes it's the only way to insure a clean fuel system.

MMO and running the engine regularly are the best way to prevent sticking valves. I wouldn't use any more MMO than is necessary. This isn't a 2-stroke engine and they generally get enough blow by to keep the piston rings lubed up. They don't run well on oil and solvent alone. It doesn't take all that much MMO to do the intended job.

We run the aircraft engines every 2-weeks if they are in flyable storage. This is considered the minimum interval for safe flight. Even 2 months is too long.
 
rotorwrench said:
The two most common problems that can happen after a car sets for a time is fuel deterioration and sticking valves.

Fuel doesn't last very long unless it is a higher quality formula like 93 octane premium. Avgas last a lot longer but it's overkill on a model A and it's not legal to run it in cars. Draining the fuel is a PITA but sometimes it's the only way to insure a clean fuel system.

MMO and running the engine regularly are the best way to prevent sticking valves. I wouldn't use any more MMO than is necessary. This isn't a 2-stroke engine and they generally get enough blow by to keep the piston rings lubed up. They don't run well on oil and solvent alone. It doesn't take all that much MMO to do the intended job.

We run the aircraft engines every 2-weeks if they are in flyable storage. This is considered the minimum interval for safe flight. Even 2 months is too long.
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Thanks, good information.
I use no crap gas in my rigs and that seems to work out great. So I think in the future I do need to use the MMO as you mentioned. Because I do leave my rigs in the shop for long periods of time and don't run them enough.
 
Don't feel alone about that. Folks don't always have time or weather that coincides with opportunity. I have helicopter customers that let them set far too long. It's what keeps money in my pocket though but I worry about them too.
 
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