AC model B

Bobby F. · Jul 19, 2012

HELP !!!!! I just purchased a 1946 model B it starts good when COLD but will not start HOT. It has to cool off completly before starting. I can pull it & it will start but I want it to start with the starter. Any ideas or suggestion"s would be greatly appreciated !!!
Thanks Bob

Janicholson · Jul 19, 2012

Check the size of the Battery cables, and their condition. They can be as small as "O" gauge if more than 3 feet long, or as small as 2 gauge if shorter. The battery must maintain 80% of voltage when cranking measured across the terminals. The ignition should see at least 70% of full battery voltage during cranking.
Timing is also important and cannot be advanced or it will turn slow or stop at the top of each compression stroke. Best of luck, Jim

Tony in Mass. · Jul 19, 2012

Coils and condensors act dumb in hot weather, probably the coil.

Bobby F. · Jul 19, 2012

Thanks, It seems to turn over fast but i'll check the voltage tomorrow. When trying to start HOT you can smell gas like it's flooding. start's good when cold though. my neighbor suggested putting another carb gasket on top of the old one. He seems to think it might be vapor locking ... Bobby

Paul from MI · Jul 19, 2012

Magneto or battery ignition? If mag, then battery cable size is not so critical, but timing of mag must be spot on. Either a coil or a condenser can cause your problem, so replace one or the other, or both and see how it works. My bet gues from here, could be impulse problems on the mag.

old · Jul 19, 2012

6 or 12 volts??? Battery ignition or mag?? Things like that is need for use to be able to help you help your self. With the lack of info do this. When hot check for a good blue/white spark that jumps a 1/4 inch gap or more. Also does it spin over as well hot as cold?? Starter could be dragging when hot

Bobby F. · Jul 19, 2012

If the coil is bad wouldn't the tractor die after the coil got hot.

Bobby F. · Jul 19, 2012

It's 6 volt with mag. Battery is very good or seems to be !! It spins very good hot or cold I dont think the starter is draging- spins over good

Bobby F. · Jul 19, 2012

Where is the coil in the mag or elsewhere ?

Tony in Mass. · Jul 19, 2012

Condensors yes, always. Coils are weird and getting weirder as quality goes down. Do you have an extra coil to try? 46? Hey is this run by magneto? All bets are off!

Bobby F. · Jul 19, 2012

Yes run with a mag !!

JMS/.MN · Jul 19, 2012

Pull starts when warm, but not with the starter- get the mag rebuilt. BTDT with WC and C years ago.

RalphWD45 · Jul 20, 2012

I hope I am wrong, because all the other suggestions are cheaper and quicker. However I have had that problem, and had to have the valves ground, to cure it.

ralph1111 · Jul 20, 2012

When you are shuting tractor off leave it running and turn off gas and leave it run out of gas then turn gas back on and try starting right away if it start you found your problem.
carb. will need attention let us know what you find and good luck
Ralph

doubleN · Jul 20, 2012

Bingo!
Getting a good coil any more is a "roll of the dice."
Based on our experiences, go to a NAPA store and run away from Tractor Supply coils.

My guess is a new condenser would help too.

But-I've seen some AC B's that were hard starters no matter what.

Dick L · Jul 20, 2012

First off do a compression check. They will start hot or cold (IF) they have compression, spark and fuel. If it starts cold and runs as long as you want until you shut it off, it most likely is not a fuel problem. Could be spark or compression. The quickest way to check for spark when hot is to pull the plug wire off, hold it a 1/8" away from the plug while cranking it over. Should be a strong blue look. When outside in bright light I use my index finger and thumb, which most will not do, but it will tell you how strong the spark is.

old · Jul 20, 2012

With a mag again how is the spark?? Has to be blue/white and jump that 1/4 inch gap. Almost bet the mag coil is getting bad and you have a poor spark

jackinok · Jul 20, 2012

no,probably not vapor locking...try this, as soon as you get off the tractor shut the fuel off.when restarting leave it off and see if it will start. it should start because the carb bowl is full.if it does you have a carb problem,maybe a needle seeping through or simply fuel level too high.probably a problem with the needle and seat.it may run perfect while running a little rich,but as soon as you shut it off carb overfills and it floods.I have a "N" ford that does this very thing. till i get time to repair it,i simply shut the fuel off every time i shut the key off. check the spark and all,as the others say but try this,it may help you find your problem.

Bobby F. · Jul 20, 2012

I checked the spark after it gets hot & I dont have blue spark. I can feel slight voltage going thru my gloves but cant get it too jump to the plug.I also unpluged it from the dist.cap but wouldn't jump there either.

AC model B

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