setting the cold timing 420C

BLS · Post by **BLS** » Sun Jun 17, 2012 12:47 pm

I know this is a dumb question for people that work on these machines all the time, but I can't figure it out so i have to ask.

I'm trying to set the cold timing and was wondering how to do that.
this is what i'v done so far:
Step 1: front cylinder (#1) on compression stroke and TDC (both rocker arms are loose).
Step 2: I can see the TDC mark in the timing window.
Step 3: the rotor is pointing to the back of the machine and is aligned up with the contact that is going to # 1 cylinder.
Step 4: ask for help!

is this right so far?
how do i set the points. I can't find anything in the manual that make sence.

Thank you
Brian

Willyr · Post by **Willyr** » Sun Jun 17, 2012 2:32 pm

the way you time my 60 is.....

Bring the flywheel around to the timing mark.

remove the #1 plug

Turn on the switch

loosen cap screws that hold your distributor locked.

rotate the distributor in the block till you see the spark.

Shut off the switch

tighten the cap screws for the distributor.

tighten the plug.

done!

foxd · Post by **foxd** » Mon Jun 18, 2012 2:09 pm

It seems strange to me that your rotor is pointing towards the rear of the crawler. If I remember correctly, when I put my engine together and timed the oil pump my rotor was pointing more towards the front of the crawler. Maybe it does not matter, but is different.

BLS · Post by **BLS** » Mon Jun 18, 2012 6:56 pm

looking in the manual, all the pictures that i have found show the spark plug leads on the front part of the cap.

I am not using the electrical system at this time, just a battery, a wire from the coil to the battery, and the wire between the coil and the distributor. I bought the tractor not running and am not sure of the conditon of the engine.

I'm just trying to get spark to see if it will run.

is the timing 180° out?

foxd · Post by **foxd** » Mon Jun 18, 2012 7:30 pm

I am wondering if the oil pump has been removed at some point and not timed with the engine when reinstalled. Do you have a service manual? It describes how to time the pump properly.

BLS · Post by **BLS** » Mon Jun 18, 2012 9:29 pm

yes i have a manual. I did not intend to go into the engine if i do not have to.

the previous owner stated that the crawler ran before they parked it in the barn and disassembled it to fix the reverser.

if the oil pump is out of time, then the rotor could be pointing backwards and still be correct for timing?

does it matter which way the rotor is pointing, the cap can only go on one way, and the rotor is pointing to the #1 spark plug contact on the cap when the #1 cylinder is at TDC, and the 'spark' is visible in the timing window.

Pammark · Post by **Pammark** » Tue Jun 19, 2012 9:40 am

Timing an engine can be done manually.

It really doesn't matter where the rotor is pointing, as long as the spark plug wires coorespond to the right location and firing order. On a four cylinder engine, normally pistons #1 and #4 are both up or down, in the same position. So TDC on the flywheel might be right for #1 cylinder or one turn out of phase.

It is good to try the rocker arms. When the cylinder is in the firing position, both rocker arms should be loose. In the opposite location, they will be tight because there is a short time, both valves are slightly open, the exhaust is almost closed and the intake is starting to open.

The spark occurs when the points just open. That is when the magnetic field in the coil collapses, and the high voltage is induced to the spark plug. The points make and break the ground. If the dozer is pos (+) grnd, like mine, the wire to the dist will connect to the (+) side of the coil and the (-) to the battery/ignition switch.

It takes a finite amount of time for gasoline to ignite, so set the flywheel a few degrees before TDC, and set the points just to open. By time the spark hits and the gasoline ignites, the cylinder will be at TDC and slightly after for the most power.

Octane of gasoline is the inverse of speed to ignite. The lower the octane the faster it burns and vice versa. So with a low octane gasoline (cheap gas), if the spark is too early, it will ping or try to run the engine backwards.

After the engine is running and warmed up, loosen the distributor and rotate it advanced or retarded to the best performance. Do this with the throttle as low as possible, to reduce the centrifugal force spark advance mechanism (if any). Too early will ping, too late will be a power loss (and extra hot exhaust).

Mark

BLS · Post by **BLS** » Sat Jun 23, 2012 8:16 pm

Thank you to all who responded with adivce.

I set the timing cold (the rotor facing the back of the tractor), it started for the first time (in about 8 years) this morning.

it is a good feeling to finally hear it running.
Brian

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setting the cold timing 420C

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