Building a 1923 T and got it started but the timing advance lever doesn't smooth out the rough idle. Didn't seem to do much when I moved the timing lever. How do I get it to idle smoothly? Thank you
A couple places to look first would be confirming all plugs are firing, good (enough) compression on all cylinders, and playing with the carb needle.
Try a little wider gap on the plugs.
First try shorting to the head each spark plug with an insulated handle screwdriver one at a time. If you notice shorting one or more plugs does not change the way it runs, that plug is not firing. If shorting a plug causes a noticeable slow down of the engine, that one is firing. If they all seem to be firing, try rotating the carburetor needle valve clockwise until the engine slows down. Then rotate counter clockwise until it starts to run rough. Set it about half way between those two positions. That should be the smoothest idle.
If you find that one spark plug is not firing, you can try another plug. If that fixes the problem you have found that plug was bad. If it still misfires, try switching the coil with another one which is firing. If the misfire moves with the coil, you have a bad coil. If it is still in the same place, you have a problem in one of 3 places: the timer, the wiring, or the coil box.
Before you go too too crazy, make a quick check to make sure there is no slop anywhere in the timing lever and it's rod.
Thank you everyone
Could one of the contacts in the roller timer not work? Just figured if one works they would all work? Thanks
Roller timers are traditionally pretty hardy. There are two things that can mess them up, however.
One is for the timer to be severely off of center with the cam shaft. Not likely if your problem is at idle speed.
The other is dirt, rust, oil, or other 'stuff' in the timer case, causing the roller to make no or bad contact with the segments. Most brands of timers require an occasional wipe-out.
I built this car from scratch. Timer is clean and the coils were rebuilt by Brent Mize The Coil Doctor so its not that. Spark plugs are new from Langs. Could be possible that one is bad. I will try carburetor adjustment and make sure all spark plugs are firing.
You may have already done this, but just in case...
James, Another possibility that can cause rough engine performance is coil box arcing. Wooden coil boxes can develop carbon tracks that divert the spark's intended destination or diminish the spark intensity. Replacement plastic coil box conversion kits are available to help ensure the full spark energy gets to its intended destination.
A comment on properly adjusted coils; Coil point adjustment is far more sensitive to physical handling than many realize. An accidental bump or difficulty installing or removing them from the coil box can result in de-tuning the point adjustment. NEVER push on the coil point elements to install or use a screwdriver to pry the coil point elements to remove the coils from the coil box! Recommend coils be checked for equal and consistent firing time OR try a set of known good coils to rule out coil misadjustment.
A good check is to stop TWO coils at once; the centre pair so the engine runs on just 1 and 4, then the outer pair to leave 2 and 3 working. Just gently press on the lower contacts to stop them moving.
This test will show if one cylinder is not working; the engine should run slower, but evenly on 2 cylinders.
If one of the tests leaves it very rough, then speed up the engine a little, and stop a third coil. If the engine stops, the remaining cylinder is bad.
Is the roller track around the inside of the timer smooth? This usually shows up more at higher speed, but could still be a problem.
Also, yes, one contact in a roller timer can be bad. I had one once that one of the contacts was grounded to the case. This will cause that one coil to fire continuously on battery.