My Willys 3A and 3B Community

TECH FAQ SECTIONS => Engine compartment => Topic started by: MikeS on April 19, 2018, 05:27:21 PM

Title: Timing Question
Post by: MikeS on April 19, 2018, 05:27:21 PM: So I have no inspection hole or timing marks on the front of the engine. What's the next best way to find TDC or 5* before ? Help! L head 4 cyl.
Title: Re: Timing Question
Post by: 1955CJ-5 on April 19, 2018, 10:39:52 PM: Do you have a notch in the crank pulley?

Do you have a timing light? Some have a knob that allow you to dial in the 5ï¿½ BTDC

There were at least three timing gear covers. One with T and 5ï¿½ grooves, one with a slight hump/bump and one with no marks.

You can find a close TDC by removing the #1 spark plug, (the engine is easier to turn if you remove all the spark plugs) placing your finger tightly over the #1 plug hole, and turning the engine until you feel the pressure of the compression stroke. This pressure will change to vacuum as you continue to turn the engine. TDC is near where that pressure changes to vacuum.

You then might be able to see the top of the piston in the bore, looking through the plug hole.

There is an add-on timing indicator but it needs a little tweak as it's for the M-38 with a larger pulley..

https://www.ebay.com/itm/Jeep-M38-M38A1-Timing-Indicator-NOS-G-740-G-758-/173130861535

I bought one and modified it...I had the un-marked timing cover..

http://www.cj3apage.com/cgi-bin/3Ayabb26/YaBB.pl?num=1372878148

Once you find TDC your rotor should be near the position shown in the picture...
Title: Re: Timing Question
Post by: athawk11 on April 19, 2018, 10:58:47 PM: Not completely fool proof, but should get you close...

Remove #1 spark plug.ï¿½ Hand crank the motor with a wrench on the front engine pulley.ï¿½ Cover the spark plug hole with your thumb.ï¿½ Turn the engine clockwise until you feel pressure pushing your thumb out of the spark plug hole.ï¿½ Once the pressure stops pushing on your thumb, turn the engine counter-clock-wise a small amount. This should get you close enough to start the engine.ï¿½

Check the position of the distributor rotter.ï¿½ If still in the stock position, it should be pointing at about 4 o'clock.

Hook up a vacuum gauge at the intake port, then start the engine.ï¿½ Let it warm up, then loosen the distributor.ï¿½ Slowly turn it back and forth to find the position where your vacuum gauge shows maximum vacuum.ï¿½ Now turn the distributor counter-clock-wise a few degrees, then lock it back down.ï¿½ You will will be very close to perfect timing for your engine.ï¿½ At this point, you will probably need to make some minor adjustments to your carburetor. Or maybe not.

Edit: Randy types faster than I do. 8-)
Title: Re: Timing Question
Post by: MikeS on April 23, 2018, 03:18:35 PM: I think I can work with most of that other than looking through the plug hole cause its a flat head and the piston is off set.