Timing notch

[Horst]

The 9-2320-218-20 I have is from May 1982 and covers non-emission and emission type engines. No reference to 2 notches. Do you have an even newer version of the TM?
Honestly was too lazy to walk down in the garage the check on my jeep but I am pretty sure there is only one. But I have a 1972 M151, so it is not really relevant. When did they make the last batch?

[Lou]

The other way to resolve this is to simply place #1 at TDC and move the spark plug wires around on the cap so the rotor is giving spark to #1 cylinder. Just keep track of the firing order and keep it the same once #1 is correct.

[Mark]

The 2 marks are line with each other on the dampner, if my memory serves me right.If I am wrong tell me.

[1SGCAV77]

My earlier post was from TM 9-2330-218-20-1-1 May 1982 with change 1, 3 Jun 83 and change 2, 1 Aug 88. Pages 4-72.2 and page 73. The atttached photos are from this manual.

IMG_2502.jpeg

IMG_2503.jpeg

There are soooo many 151 running on daily cruises doing the simple timing methods. I prefer using TM’s that were one book. Prior multi volume TMs. But, that me.
This is best site for knowledge of 151 family jeeps. Keep them rolling.

[Horst]

Appreciate the update. So they must have incorporated that change pretty late.

[rickf]

That is really interesting. Shows how the government never sleeps, also shows how they just have to waste money to pay someone to rewrite a manual and add parts to the system just to do the same exact job the previous manuals did. Note what it tells you to do if it does not advance to that mark, REPLACE distributor. Same as before with a lot less procedural BS. So it took an addition to the manual which I am sure cost millions when all is considered. Plus another couple million for additional parts and distribution and stocking and cataloging.
Government efficiency at it's best.

Sorry for doubting you, I wonder if Ken has the change orders in those manuals?

[m3a1]

Now is a good time to do a double tap on the matter of setting up your engine timing back up if you find you've set it up 180 degrees off plumb. Sure, you can swap wires around and leave the next guy scratching his head (and that next guy may be you, some years down the road) or you can sort it out, one and done.

Did you know that there is a handy little device that resides just below your distributor? It's the connection between distributor and the rest of the engine and like your distributor, at one end it has the offset notch (you DID know your distributor drive was offset, right? RIGHT?!). At the engine end of this crafty little piece is a centered notch. So, if your timing setup is 180 degrees off plumb, the only thing you'd have to do to solve that problem is, pull the distributor and with a small magnet, reach down in, lift the interface component up, turn it 180 degrees and stick it right back in. Then turn your distributor drive 180 degrees and put it back in. You've just returned your timing to where it should be. Easy peasy.

[rickf]

But again, Mark the distributor so you will KNOW it has been modified!!!!

[mike]

Hello everyone,

Im sorry for hijacking your thread but I have a question regarding the notch on the pulley. Mine only has one notch and it looks factory made however when I tried to time it using a timing light so that the notch is in line with the pointer, the engine's power fell on its face. When I took the jeep for a test drive it wouldnt accelerate too well and backfired a lot when letting of the gas pedal. I took out the no 1 spark plug to see the piston move and I believe the notch actually marks the TDC, not the 6 degree mark. Is it possible like that? I assumed it is so I figured out approximately the 6 degrees BTDC and reset the distributor so that the pointer would match my new mark. Now it runs good and accelerates as it should. However I am still not 100 percent confident about this.Thanks for any input.

regards,
Mike

[Sundawg3]

I know I'm new to the M151 thing but wanted to through my two cents in. I read a post by Mutt Guru, on this forum, about your situation. I planned on doing what Rickf recommended after purchasing the Mutt. Valve clearances, points gap, plug gaps and timing. Mutt Guru explains the additional mark being the 6 degree where people used a chisel or hacksaw blade to make the mark. He also explains how to reset the timing when the oil pump is 180 out like your situation. I don't have the link to the thread cause I printed his instructions for static timing then followed them exactly like he said. My engine runs better than ever since doing all as directed. If you search the forum I'm sure you can find it. Maybe search (STATIC TIMING)

[rickf]

The M151 engine needs to be tuned as a complete unit and not just bits and pieces. If you try to do it that way you will be chasing your tail forever.
If you have points they need to be set before the timing since points change will change timing. If the pulley has one mark it IS 6 degrees, There are NO TDC marks. The order of a tune up is as follows, and there are no short cuts. Valve adjustment is done first, Then the points if you have them, then the timing. And the very last thing to get done after verifying all of the above is carburetor adjustment. Everybody wants to blame the carburetor for drivability issues when more than half the time it is one of the other components. And a note on the timing, If you try to time it by ear then yes, it will run better at idle with the timing advanced. BUT, That will cause issues at higher rpm when the centrifugal timing advance comes in and then the timing is too far advanced.

[rickf]

I am going to add in here that with all the 151 engines I have worked on I have never personally seen one with the extra timing mark for total advance on it. But it obviously exists as was shown above. But all other 151 timing marks are at 6 degrees unless someone has added it with a chisel or saw. Either of these will be obviously different rom the factory smooth notch.

[mike]

Thank you for quick replies. Rick, before I touched the ignition timing I did all the other adjustments mentioned (valve clearance, points gap, plug gaps). I will try to line up the original notch with the pointer again and then re adjust the carburetor. To be honest, I didn’t think I needed to mess with the carb at that time since I had my vacuum gauge hooked up and it showed steady reading of 19-20 in - I assumed it must have been the timing which caused the problem so I advanced it back to what I thought to be the actual 6 degrees btdc. I really want to do it by the book, no shortcuts and I didn’t feel comfortable with setting it by ear. Thanks again for the comments. I will keep you posted on this.

[rickf]

If you had 20" of vacuum I am guessing you were advanced on the timing. Have you made any real adjustments to the carb? Is it an emissions carb and has the plug been removed from the idle mixture screw? Is this a new condition for this vehicle? Is this a new condition for this vehicle? Did it run better before?

[mike]

It is the emissions carburetor model 13660 B dated 1981. The plug is removed exposing the adjustment screw. It has been cleaned and rebuilt with a new rebuild kit 3 years ago. I adjusted it accordingly to achieve the highest vacuum reading on the gauge and then adjusted the throttle screw to the lowest smooth idle. The engine ran fine before but since I wanted to perform a complete tune up I also ended up checking the timing as well (which was way too advanced as I now understand). Im a little embarassed to admit but up to recently I never checked the timing before with a timing light. Can you please elaborate on your suspicion about the 20" vacuum resulting from the advance?