willysmjeeps.com

Help guys.
After a rebuild, pistons, rebore, shells etc I built the engine up, it's now in the jeep but I think I've made a mistake with the timing.

Setting the front pulley to 5 degrees before TDC at the top of the compression stroke, my rotor arm is at cylinder 3 and is way past cylinder 1. Going anti-clockwise.

Obviously it won't start.

I put the oil pump and distributor in while I was building the engine up with the head off so I could see TDC.

I wondering if I might have put the oil pump and distributor in with the engine 360 degrees out?

Any ideas greatly accepted.

Thanl you,
Dave.

Had fun with this about a year ago. Choices are pull the distributor and oil pump again, or move the spark plug wire on the cap to see if you were one off.

Update.
Sorted. At 5 degrees BTDC dropped oil pump off, pulled distributor, reinstalled at No1 and re set points.

Still won't bloody start though. Grrr.
Cheers, Dave.

Timing checks are so simple most folks forget how hard setting the engine's internal timing up really was.

The engine timing has to start with cam to crank timing. Then ensuring that #1 is TDC ON COMPRESSION Not Exhaust (180 deg's out). Then comes where is the mark. Early M38's were on the flywheel but the flywheel could be installed in two positions 180 deg's away from each other. Then came the late M38 with the front timing marks on the crank pulley and timing gear cover. Then came the interchanging of crank pulleys and timing covers which had their timing marks in several different places. Finally you have all the timing marks at their correct locations and #1 piston TDC ON COMPRESSION! Now comes the oil pump indexing and finally the distributor installation. Then you must be sure the plug wires are arranged correctly and the Army managed to get that wrong in at least one of the manual illustrations which frustrated a lot of folks.

As you can see there are a dozen stumbling blocks tossed in front of you to get the the simple task of checking ignition timing.

HI Wes,
thank you for the reply. I figured what I'd done was when I was building it up I got the bare block and No1 to top to TDC and looked at the valves, thinking if they were both closed I was on TDC compression.
I'd had a pig of a job getting the distributor tang to align with the slot in the oil pump so I was deading doing it in the frame.
In the end it turned out not to be too much of an issue.

So in the end I think what I had done is put the distributor in 1 rotation of the crank out. Given the rotor was 1 quater of a turn too far ahead would that sound right?

Anyway, we've had a couple of 'spits'back througn the carb while trying to start it so that's some progress. We'll have another go before we put it away as it's bloody cold here tonight and no fun on the drive.

All the best, stay safe, Dave.

I never thought about moving the wire on the cap!

Hi David,
Wes said "The engine timing has to start with cam to crank timing."

Only because I didn't see your reply to that anywhere, when the engine was assembled were the timing marks on the crankshaft and camshaft gears aligned as shown on Figure 77, page 93 of TM9-1804A?

Thought I'd ask just in case.

And you're positive the firing order is correct?

Good luck!

Hi,
yeap, that was the easy bit,
Ta, Dave.

HI Dave how are you ?
Is your M38 back on the road.
I set the timing with max vacuum on idle, bit more than 5 degrees i think.
Setting, change and testdriving until you get the best power, that's was my way years ago. I have made no changes for many years and the jeep is still driving well. I restored the jeep 15 years ago, and i need new tires (cracks).

All the best during this corona times..

gr Erik

Hi Eric,
it's fine now, it was actually an M201 engine I was building up. It's been years since I put one of these engines together and I was 'running on autopilot'. Doing, but not thinking.

1. I forgot the bolt under the back of the distributor. So when I put the disributor hold down bolt in, the distributor was still moving. A head scratching monent.

2. Then I forgot that the French move the HT leads anti-clockwise 90 degrees. So you time the engine up exactly as an M38 but the rotor in the distributor points at Number 3 instead of Number 1. Things you forget and have to re-learn every ten years!
I was just going to move the leads round but then I thought about the next person that might look under the bonnet and it's always better to build to the manual.

Hope you are all well in these strange days we are living through right now,
stay safe, good health,
Dave.