the biggest secret ??

ericlb · Oct 10, 2016

im working on a 1928 or 9 caterpillar 20, gas engine, mag style ignition, i cant get it to fire, and i cant find the actual firing order anyplace, my manual doesnt have it, tractor data doesnt have it, and
several web searches dont have it, does anybody here know? what the tractor has wired up is 1-3-2-4, with ccw rotation of the assessory shaft, engine is hand crank only, ive primed it with no results, rebuilt
carb, ect the mag should be hot enough as it zaps the heck out of anybody holding a wire, i can also hear the mag click on impulse, but not even a puff,

Adirondack case guy · Oct 10, 2016

The only other fireing order on a 4cyl that I know of is 1-3-4-2. It should fire on 1 and 3 though, if you are in time. Are you sure you are not 180* out??? or the impuls on the mag has alread snapped over center at TDC.
Loren

retired farmer · Oct 10, 2016

Supposed to be 1-3-4-2.

Dune Country · Oct 10, 2016

you could pull the plugs and valve cover and roll it over and see which intake valve goes down 1st 2nd etc.

oldtanker · Oct 10, 2016

Take this over to the ACMOC site. Lot of old cat guys there.

Rick

Janicholson · Oct 10, 2016

With the plugs out, put a chicken feather in each with the quill out (keeps the feather from being sucked in) then have someone watch as they are blown out. marking down the sequence. It doesn't matter which one blows out first just put them in order from One. Jim

Steve@Advance · Oct 10, 2016

Have you verified spark at the plugs? Try pulling them out, laying the plug on the head and watching for spark as it is cranked.

Try a few squirt of ATF in each cylinder. The rings may be dry or washed down from priming.

Are you sure there are no stuck valves?

rustred · Oct 10, 2016

yes as jim says.. but u could always give it a pull if your tired of cranking, sometime thats what it takes when something has sat a long time it wont build enough compression to fire. good to lube the cyl's first. have had that happen a few times.

pete 23 · Oct 10, 2016

Some 4 cylinder engines fire 1243. Allis Chalmers comes to mind. Most are of course 1342. You can look at the valves to tell or carefully check compression of each cylinder when turning by hand.

guido · Oct 10, 2016

Hello ericb,

Firing order is either 1-3-4-2 or 1-4-2-3. I don't think that 1-3-2-4 is the correct firing order. Double check timing is correct, You did not say if it is popping throught either the intake or the exhaust? That would indicate a spark is there,

Guido.

ditchwitch · Oct 10, 2016

OK i am going to ask a dumb question. Are you rotating it the correct way with the hand crank??? If you say it has spark and gas it should do something.

Royse · Oct 10, 2016

"Some 4 cylinder engines fire 1243."

Yep. Fords for example. Some of them CW, some CCW.

I wish I had more to offer to help you Eric, but I don't.
If it were anywhere near close, it should at least fire on one
cylinder. You said "not even a puff". I assume that means no
cylinder is firing at all. Have you verified rotation direction?

T.R.K. · Oct 10, 2016

If it was me, I would start with #1 cylinder (Front). Remove all the sparkplugs, Hold a finger over the plug hole and have a helper roll the engine over with the crank. When it starts up on compression it will blow your finger off the hole.

Then look at the magneto. Which plug wire is the rotor pointing to? That is #1. Then remove the valve cover or covers, The rocker arms for #1 cylinder should both indicate the valves are closed and have some 'clearance' meaning the rocker has a tiny bit of play with no pressure on it.

Then roll the engine 180 degrees with the crank. Which pair of rocker arms for which cylinder are both closed now? This is the cylinder that is now ready to fire. Where is the rotor on the magneto pointed? The wire from that post on the magneto needs to go to whichever cylinder is now ready to fire.

And so forth until you have all 4 cylinders.

Like the other guy said, If the engine has been sitting, you may have to squirt some oil into the spark plug hole to get enough compression for it to fire.

37chief · Oct 10, 2016

What ever you just be careful cranking that thing by hand with timing problems. A good place to get a broken arm. Stan

ericlb · Oct 10, 2016

the hand crank only catches one way, the crank has the notches designed to kick the crank out when it does fire , hopefully, and with help from the big spring on the shaft so no problem there

ericlb · Oct 10, 2016

thats whats bothering me the most ,by having a hot mag, and no attempt to fire at all, it could fire at any time

Bob · Oct 10, 2016

From the Caterpillar Gas Tractor Restoration and Interchange Manual: "With the exception of the 2-Ton, all of the gas Caterpillar tractors have a firing order of 1-3-4-2." .

Now that that's solved, let's think outside the box and use some sort of non-human spark tester, and see if it has a hot blue spark.

Shocking a human and firing a sparkplug under compression are two different things!

ericlb · Oct 10, 2016

no pop at all, even with new plugs and new solid core wires, thats what is most odd it should have something somewhere ,even if the previous work done was not right

ericlb · Oct 10, 2016

i thought about that but the last old crawler we tried to pull start had so much gear reduction that even in high gear it just slid on the ground and would turn not the engine over

ericlb · Oct 10, 2016

thanks bob

4wdtom · Oct 11, 2016

Briggs and Straton used to make a nice little spark tester. You put the spark plug wire on it and clipped it to ground and inside was the proper space between conductors for a good spark to jump and you could see whether or not you had a nice spark. No holding the wire and trying to maintain a gap and maybe getting zapped while doing it. I don't know whether they still offer it, 25 years ago when I bought mine it was only $10 or $15. Worth it. You know about the spark after using it.

tractorguy2 · Oct 11, 2016

I have one of those spark testers. You can also adjust the gap.

the biggest secret ??

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Similar threads