Set Timing M38

lee12 · Post by **lee12** » Wed Jan 27, 2016 10:43 am

I am having trouble getting my M38 timed. I am following the instructions that Wes has written that are floating around on here in several discussions. I set the points, found timing marks, set to 5 degrees, the rotor was in the correct # 1 position close to a high point. and then this is were I'm confused, when I try to advance the housing so the follower tab is in the middle of the next flat of the cam, my housing hits the engine block before the tab ever comes off the high point. Engine will start and idle but will not run well with acceleration, misses and low power.

Also, when checking advance, when I grab the rotor and twist clockwise it does not move, but if I twist it counterclockwise its will move a bit then snap back. In the instructions it says it should be twisting clockwise.

Any advice?

4x4M38 · Post by **4x4M38** » Wed Jan 27, 2016 1:11 pm

I remember a post here where somebody was having the same
problem with the distributor. Something is out in the installation.
Maybe clocking the distributor?

I'll go look in the search stuff. I'd start there and fix it first.

4x4M38 · Post by **4x4M38** » Wed Jan 27, 2016 3:01 pm

I PM'd this to Lee, then figured it would be helpful over here.

"Did you pull or adjust the oil pump?

If the oil pump is not indexed correctly it will not let you adjust the distributor properly. The distributor is tied into it.

http://www.willysmjeeps.com/v2/modules. ... p+indexing

Don't know if you read this post but it is the one I was thinking of."

lee12 · Post by **lee12** » Thu Jan 28, 2016 8:32 am

Thanks for the suggestion. And thank you too Wes for your help. I believe Ill reindex. I had the engine rebuilt and it was installed when I got it back. Now Im thinking I should just pull the timing cover and make for sure my marks are correct as well.

This maybe dumb, but do you think its worth pulling the engine again or just do it with engine installed, that being timing cover to check cam and TDC and reindexing oil pump.

Post by **wesk** » Thu Jan 28, 2016 10:52 am

Re-indexing the oil pump to the cam without observing the front gear timing marks can be done but you always risk up to a 5 degree error since the only choice to confirm valve and piston position are mechanically by bringing #1 piston TDC on compression. These engines will not offer you a fixed TDC point for the piston because there is a flat spot of about 5 degrees at the top during rotation of the crank where there is no perceptable piston movement. You can reduce the error incurred using this method by doing the rotation very slowly with a dial indicator recording actual piston movement. You stop rotating the crank the instant piston movement stops on the way up then mark a reference point on the pulley and block. Then continue rotating until the instant the piston movement starts again. Now make a second reference mark on the pulley. Divide that distance between the first and second mark in half and you will be as close to actual TDC as is humanly possible without a visual angle reference on the front gears.

Before I jumped in to this issue with both feet I would first confirm my timing marks on the pulley using the method above. Then with the #1 piston properly set at 5 degrees BTDC per current timing marks remove the distributor and observe the indexing of the oil pump tang. There is a very good illustration of this in the M38A1's engine manual TM 9-8015-1 that is not in the M38's engine manual.

With #1 at 5 degrees BTDC, if your pump is already in this position then most likely your plug wires are not indexed correctly in the cap. If your pump shaft is not in this position then you will need to remove and re-install the pump. Since it is a fresh rebuild the pump should remove partially without tearing the gasket for the re-indexing. If you tear the gasket then make sure you install a new one.

Another point seldom covered in these discussions is the big difference between WWII chain drive camshaft L134 engines vs post WWII gear driven camshaft engines. The camshaft turns the opposite direction and this in turn rotates the oil pump and distributor in the opposite direction.

The helical cut drive gears on the camshafts and the helical cut driven gears on the oil pump are reversed.

lee12 · Post by **lee12** » Thu Jan 28, 2016 11:19 am

So one would just pull the head to use dial indicator on #1 in order to make the two crayon marks?

Post by **wesk** » Thu Jan 28, 2016 11:43 am

Yes. Some folks have fabricated a wigler for the L134 that will pass through the spark plug hole and reach over to the edge of the top of the piston and use the wiggler to actuate their dial indicator. If a quality fabrication process ends in a wiggler with firm movement indications it can work accurately enough.

4x4M38 · Post by **4x4M38** » Thu Jan 28, 2016 2:01 pm

Wes, I have a dial indicator that has a separate magnetic base and attachment.

It has about 2" between the tip of the pointer and the bottom edge of the dial.

Is that enough to stick in the spark plug hole and get TDC?

Post by **wesk** » Thu Jan 28, 2016 2:19 pm

Take a plug out and look in the hole! You will not see the top of the piston! That is why you need a wigler to take care of the 90 degree turn needed inside the plug hole.

4x4M38 · Post by **4x4M38** » Thu Jan 28, 2016 2:27 pm

Sorry, Wes.

Brain fart. Eating way too much Bondo lately.

Lee, I can get this dial indicator to you if you don't have one and can come up with a wiggler. Let me know.

lee12 · Post by **lee12** » Tue Feb 09, 2016 3:41 pm

Thanks Brian, Ive been out the last week and just got back in town, I'm going to fiddle with it this evening for a while and I'll see what I come up with. May give you a shout.

4x4M38 · Post by **4x4M38** » Tue Feb 09, 2016 4:40 pm

I'm headed to Priddy in the morning. I can meet you in town
with that dial indicator if you need it. I don't have a wiggled though.

lee12 · Post by **lee12** » Wed Feb 10, 2016 9:46 am

I constructed a wiggler, if you will out of copper wire, and found that my timing marks (TDC) are indeed lined up with my pulley mark. I bent the wire so that it fit down to the cylinder and then made a holder for it that connected to the rod that goes from the radiator to the crowl so I could see and mark movement. I followed wes's timing instructions and I now have it fired up and idling well. Tonight ill finish up with it and hopefully take it out for a test drive.
Thanks for the offer on the dial indicator.

4x4M38 · Post by **4x4M38** » Wed Feb 10, 2016 10:08 am

Congrats Buddy!
Might see you tooling around when I head home this evening!

lee12 · Post by **lee12** » Fri Feb 12, 2016 8:13 pm

Update:
I have got timing set now. I was burning up points after driving about a mile down the road. I had the distributor advance weights and cam bushings redone. Which work great now, by AJP. I couldn't figure out the burning points. Then I pulled the coil replaced it with new coil and now no more points burning, at the same time I put a new cap on and condenser. It runs great now down the road, but when at idle now it fluctuate idle and almost wants to die then it will level out and idle fine, repeat over and over.
Am I looking at carb float problems? I already sprayed the base of carb and no changes in idle so I feel like I have a good seal.
Any thoughts?

Set Timing M38

Set Timing M38

More issues