NO START JUST PUFF

tddiller

New User
Hi folks....just registered as a new member.... i inheritted a 1950 8N/B that i cannot get started....i am a shade tree mechanic with good basic knowledge.....my new to me tractor has been sitting for a year and used infrequently prior to that.....in a nutshell, the engine just "puffs" like a train when cranking.....the spark jumps 1/4 inch.....installed new autolite plugs...timing set anywhere from 4 degrees to TDC via the static method trying to start the engine...carburator visually looks fine upon teardown with the float set correctly........and finally the air hose is disconnected at the carburator to complete the trifecta of air, fuel and spark??? observations are: more fuel than I would of expected sitting at the bottom of the air horn area but not excessive...seems to "puff" more at about 3/4 choke setting....and I am NOT sitting in the seat with cluctch depressed while cranking.... finally it appears to have a 12 volt battery with a resistor installed prior to the ignition system, and the spark looks fine????

Any help would be appreciated.......dave
 
Is your fuel fresh? Do the plugs seem wet after you try starting or are they dry? If they are dry try priming 2 or 3 cylinders with a little shot of gas.
 
Have a helper make a start while you hold your hand over the throat of the carburetor to see if there's good suction. If there's very poor suction is an indication of low intake manifold vacuum. Do a compression check and post the readings. Hal
 
(quoted from post at 13:08:14 04/22/14) Have a helper make a start while you hold your hand over the throat of the carburetor to see if there's good suction. If there's very poor suction is an indication of low intake manifold vacuum. Do a compression check and post the readings. Hal

thank you all for the your replies......forgot on first post to list all cylinders read 95-100 during compression check, I will check out the hand test on the carb.... but note even fresh spray start directly into the cylinders would only result is a couple of puffs??? No diesel is involved......I put fresh 91 octane unleaded in the tank..........cheers
 

Yes the plugs are wet (but not dripping wet) and I also put spray start directly into each cylinder, got only a few puffs
 
I would pull the spark plugs and squirt engine oil on top of the pistons. Then bump the engine over easily and install the plugs. Then see if it will start. Hal
 
Make sure your plug wires are in the correct firing order on your cap to your plugs as the rotor rotates CW. Hal
1-2-4-3
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Put a new set of spark plugs in it. Go as hot as you can get. I personaly would not use champions. High octain fuel is more prone to wet fouling than low octain. The higher the octain the colder the flame. Once a set of plugs is wet fouled it is next to imposible to make them fire under compression.
 
Firing order is right but the N's turn CCW. 2 and 3 need to swap places.

Gas at the carb throat is too much choke. Remove plugs and clean with a propane torch.

AL437's are prefered.

Charge the battery good. Starters pull lots of amps and can leave little juice for ignition if low. Give it a shot of ether in the carb and don't use any choke.
 
(quoted from post at 20:14:55 04/23/14) Firing order is right but the N's turn CCW. 2 and 3 need to swap places.

Gas at the carb throat is too much choke. Remove plugs and clean with a propane torch.

AL437's are prefered.

Charge the battery good. Starters pull lots of amps and can leave little juice for ignition if low. Give it a shot of ether in the carb and don't use any choke.

Thanks for your response.....i did buy the autolite 437s and will use the torch to dry them out.......ether sounds like a good idea....
 
If you can get it to hit a lick or two on ether, it will run. You may not be out of the woods yet, but at least you know you are moving in the right direction.

Your compression test numbers are OK, but 90 is the minimum spec. Remember, ether does not require compression to fire.

Gas fouling your plugs is more than likely the issue. Do what was posted and put a little oil in the cylinders to up compression. DONT put any gas in the cylinders since this is what cause the problem to begin with.

Maybe a two second shot of ether in the carb throat and crank with no choke.

On firing order, if your plugs wires are in the tube on top of the engine, make very sure that where they connect on the cap match the plug they are running to. Cylinders are 1-4 front, nearest the rad, to rear. Easy to mix up 3 and 4.
 
Sorry about not following up till now, but I finally solved the problem and the engine runs like a champ! The actual plug wires were 90 degrees off from where I expected them to be. The dist cap is farely old and if it has a "1" molded into it I can't see it. Somewhere I thought I saw a picture of the firing order depicted just like on this thread ( the distibutor listed is not the side dist. I have, but the positioning of the wires is what i had in my mind. ie. No. 1 is in the 10-11 oclock position. I had to pull the valve cover off to match the valve action with the rotor position and in fact as my distributor is installed, the no. 1 is in the 7 to 8 oclock position. I know if my distributor is 90 degrees off I can easily fix the problem by pulling it out and turning it, but I am not sure what clock position the rotor is supposed to be when firing the no. 1 cyclinder??? Early on I did try the thumb over the spark plug hole while watching the rotor but obviously I missed it by 90 degrees.

THANK YOU EVERYONE
 
Good deal. Glad you finally got it going.

The photo posted earlier isn't an N distributor at all, front or side mount. So that did confuse things a bit.

A front mount has #1 at about 11 o'clock. See below... They can only go on one way. No way to clock it differently.

Front mount with CCW rotation. Firing order is 1243.

13
24

Side mounts can be clocked any way you like. As long as #1 at tdc is #1 plug wire. Attach others wherever they fall.

Every engine I do, V8, 6 cyl, or 4 cyl. I clock the distributor so the rotor points at #1 at TDC.
 

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