drove the t about 40 miles today, 3 trips to town,ran super on last trip was about home and started a miss at 3/4 throttle,full advance, nothing i adjusted made any change, got home ok let it sit, hit starter and it locked was able to free it by rocking car, anyway miss is still there.ideas as to where to look?? and new tailgate sign
Try to isolate the miss to one cylinder by shorting out each spark plug or holding the points open. If you find one that is missing, then check wiring, switch coils and/or spark plugs around.
Other then that just go over the basics of what it needs to run, Compression, Spark at the correct time, and Air and Fuel at about the right mixture.
are you running buzz coils or a distributor?
Don't forget the timer.(if you have one).
buzz coils, and i cleaned it,did not help, will trace it in the morning,,just keep learning about this T stuff.
Mine was missing at any speed. One of my coils had a problem, so I gave all four to a friend to check out. Problem solved.
Ronnie, there's something you said about full advance. I seldom run my model t's on full advance. Unless I'm giving it all she's got like I'm in some kind of race, and I never am, I usually run my advance about half way down or so. Too much advance can make her overheat. Maybe you know all this Ronnie. I'm just wondering. And who's to say I haven't been driving my car wrong all along. I've only been at this a little over a year myself.
coil problems, go see Ron or Brent, When the car is running look at the coils, if you see it sparking real bright and the others are not, there is the problem child!
the location of the advance lever is dependent on many things, the sweet spot varies from vehicle to vehicle, even different timers will effect its location.
one of the easiest methods of miss diagnosis on coils is to turn the key on batt. and hand crank it and listen to the coils as they buzz. if one doesnt buzz, you know theres a bad connection in the coil box, or somthing wrong with the coil, or the timer. if all coils are buzzing, then theres no connection between the sparkplug and the coil.
or you can accoplish the same thing by starting the engine and creating a gap from the top of each plug and the block with a screw driver. you should get a spark, if not you have idendified the missing cylinder.
tip: be carful how you grip the screwdriver. if you are in contact with the shank, you will get a shocking surprize.
Matthew, I found a friend has a screw driver with a shank all the way through the handle to the palm end.......Shocking...That one hit the floor and the miss diagnosis proceeded with a "normal" screw driver.
Over the summer I had a miss that would show up about an hour into my driving... I traced it back to a coil braking down after it got hot, put in another coil problem solved.
As stated above start the car you can push down on the points to find the bad coil or short the spark plugs with a screwdriver, when you find the bad one as your checking it will not change the way the car is running. I'd start with the plugs first to rule out a bad plug.
If your starter is hanging sounds like a bad bendix or broke bendix spring...
A bad plug will probably still show spark from the plug wires. Matthew, I know the "sweet spot" can be in different locations on the advance lever. But I don't believe I've ever seen a Model T where the sweet spot was full advance.
A couple of the Ts I have had needed full spark to run best, and full retard to not backfire. Probably the POJ timer I was running.
Quick advice comment. It sounds as though you will have to pull the starter to check it out. I didn't notice anyone saying to PULL THE BENDEX END APART FIRST!
Drive carefully, and enjoy the holidays! W2
haha, wayne i almost included that in my post,
ive never had a T starter lock up on me, but ive seen an A do it before. and when they lock they LOCK.
Check out the coil box terminals and terminal bolts. If it still has the original bolts still in it they can be the problem. The copper plating gets corroded where you cant see it.
Replace them with new ones and you can tell a big difference even if your T wasent giving you to much trouble.
I think the starter problem is co-incidental. Not related to the miss.
The condition of valves was not mentioned. While the most likely cause of the miss is in the electrical system, the valve could be sticking open or burnt on one cylinder, so a compression check is called for. You should have around 50 PSI on all 4 and they should be nearly even on compression. If one is 0 or considerably lower that could be the cause of your problem. It could even be a blown head gasket between two cylinders. In that case the miss would be on two adjacent cylinders.
As to possibility of electrical problem. When you ground the spark plugs at fast idle notice one plug makes no difference, but the others when grounded cause the engine to slow down, the problem is in the cylinder which made no difference. In that case try switching that coil to another position and if the problem follows the coil, your problem is with the coil. If it is still at the same cylinder, check the spark plug to that cylinder. If you have a spare, try it in that cylinder. Or if no spare swap the plug with another cylinder. If the miss follows the spark plug, you have a fouled spark plug. If that does not fix the problem clean the timer and check continuity of each wire between the timer and the coil box. Eventually you will find the cause. Sometimes it can take a while. You could also have a carbon path burnt in the wood of the coil box. This is especially likely if the car has been run with a wet coil box. I had a bad brush on a new day timer at one time and it would run fine when cold but after it warmed up, the brush would not make contact with all the points inside the timer. Every thing I did to try to find the problem caused the engine to cool off and I thought I had fixed the problem, but as soon as it warmed up again, the trouble would re-appear. Well I did re-wood the coil box, and put new points on the coils and adjust the coils, cleaned the timer, replaced the spark plugs, but the one thing causing the trouble was missed every time until I finally replaced that brush.
Hey, maybe it's a hole in the piston or a broken compression ring. Or a flat lobe on the camshaft. Or... Hey Ronnie, didn't you tell me once that you're actually a mechanic as a profession?
no not a pro, old drag racer small block chevy,i understand them,but i am enjoying learning the T
If your coils have not been setup in an HCCT type coil tester, I would start there. If nobody around you has a tester like that to test your coils for you then contact Ron Patterson (a.k.a. Coilman) because he keeps a set of tested and ready-to-go coils that he often loans to folks to plop in and try which can really help find things like an intermittent ignition problem.
I used to drag race small block (265) chevy's in a '56 sedan at drag strips around IL during the 60's. Fun times but now I like the slow lane ha ha.
Ronnie - You mentioned "full advance". I believe this is the position that can sometimes cause one of the timer terminals to short out on something. Can't remember what the "something is", but might be worth checking the possibility of full advance causing one timer terminal to come too close to something which could cause a short, or rather,...an unintentional grounding of that terminal.
Harold,you are referring to the bolt directly below timer. It should be installed with the head up so timer contact doesn't hit it.
Thanks for the "heads-up" Jack,.....couldn't remember but I knew there was some sort of a not too uncommon problem that could occur in that area........