Stuck valve....I'd guess??

M

mndodge

Member
This past weekend I fired up the new project I brought home a week ago.
I cleaned the points, changed out the condenser, replaced the coil and also timed the motor. I changed the condenser after getting it running the first time and "seemed" to make a difference after starting it the second.
The carb was said to be rebuilt 10 years ago and never ran, I took it apart after starting and cleaned jets and reset.
When it starts it starts good, but when I go to rev it up a little it seems to go up a bit and then it's like it hits a dead spot and doesn't want to do any more. When I timed it it seemed dead on, but I know with the cap off the rotor seems to strike just before the pin rather than dead on or on the down side....so with that info, can anyone help pick my brain??
Thanks for any ideas......
And I also did change the plugs and I believe correct gap is .025?
 
Yep I did, I double checked that twice......but as your post mentioned, it sure seems like the timing is somewhat retarded with the lack of power.
But it fires right up when starting with spark advance lever all the way down.
 
mndodge said:
Yep I did, I double checked that twice......but as your post mentioned, it sure seems like the timing is somewhat retarded with the lack of power.
But it fires right up when starting with spark advance lever all the way down.
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Remember the rotor turns counterclockwise, so the points should be just ready to open when the trailing edge of the rotor is at the edge of the cap contact, with the spark lever all the way up.

Marco has posted some good pictures of this, and maybe they are also on his website.
 
I did check my other 29 that runs like a top and the rotor is as spot on as it can be in comparison.....just scratching my head on this one???
 
700rpm said:
Gap should be .035.
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I will have to pull and re-gap the plugs, at .025 wouldn't the spark just be a little hotter or is the difference enough to make a big difference?
I also looked at Marco's chart and that's where my rotor is, same as picture he has on his site.
 
Don't get confused fellas. Point gap is .018" to .022". The spark plug gap is .035". Did you richen the fuel mixture with the choke rod for a cold start and warm up? A lean mixture will make it sluggish. When it doesn't accelerate like you think it should open the choke a quarter turn or so and see if that helps. These carbs are all different after 80 yrs. and many rebuilds. If richening the mixture doesn't help, go back and check the timing again after looking at Marco's information.
 
You guys have great info, I thought I had done all of the above but will have to gap the plugs again, it also seems that when turning the adjustment rod, it doesn't seem to change much and I did check to make sure it is turning the adjustment in and out and it is....it's just like hitting a wall and running out of power.
And the more I think about the stuck valve.....if that was the case, wouldn't it be a little tougher to start?
 
Have someone press the gas pedal all the way down. While you are watching the carburetor. Check to see if the butterfly is opening all the way. Adjust as needed. Tony
 
If you had a stuck valve, you would lose compression on the cylinder that the valve was stuck on and you would get a dead miss. It could be that you are tightening the cam screw with the backlash on the wrong side of the rotor. The distributor turns in the counter clockwise direction when the engine runs. When the cam screw is tightened, there should be no clockwise backlash. There will usually be up to 1/2 inch of backlash in the distributor shaft. Let all of the backlash be in the counter clockwise direction when the cam screw is tightened or the timing will be way retarded. If it cranks with the spark fully advanced, the initial timing is retarded!!!!! If the points gap is too small, this will have a retarding effect. The points gap should be .018 t0 .022 . I set mine at .022. Another thing to look at is the movement of the upper plate in the window of the distributor cap body. The lever on the upper plate needs to move all the way to the passenger side of the cap window when the spark lever is all the way up as when fully retarded and all the way to the drivers side of the cap window when the spark lever is fully advanced. The two tooth steering column tube is adjustable to correct this condition.
 
I will just keep putzing on it and look over the steps a few guys mentioned on here, sometimes a guy thinks to much and maybe overlooks something simple that could be the cause.
 
I've said this before but sometimes you need to step away from a problem for a while and then revisit it. Many times the answer will appear when you least expect it.
 
The compression test is my next step.....and I probably should of dis that first off to see what I was really working with.
But with the flat spot it has, it very could be a weak cylinder or more.
 
Just to give you guys a good laugh on a Friday......the odometer only shows "6" miles on it, so it should virtually be a new motor right.....hahaaaa:D
 
Is it skipping/misfiring? Or does it just have a flat spot ? The sparklers gapped at .025" isn't going to hurt anything and I seriously doubt will be part of your problem.
The left hand lever needs to be fully retarded/up when the timing is set and remain up during starting. Once running the lever should be able to be moved thru full travel without anything happening other than the engine picking up speed and running a bit rough at full advance while at idle. Once started the lever should be pulled to about the 9:00 position.
The engine should then be able to be accelerated. A stumble or flat-spot leads me to think you have a carburetor problem[ leak or dirt/varnish] if the engine idles smoothly. Where is the idle mixture set ? It should be roughly .5 to 1.5 turns out and set to best idle, every engine is different.
You can get some kind of idea of the compression just by sticking your thumb over the hole while cranking.
 
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