Distributor swapped-more surprises...

[Cal_Gary]

As many of you know, I run a 12 volt system on my M37, to include a civilian distributor and oil pump. Well my wife finally talked me into getting a new distributor because the old one was completely worn out. The new distributor (civvy) arrived late last week, is an exact match, and I installed it exactly as the old one came out, noting the rotor position, plug wires-to-cap, etc. To my great surprise, after install it wouldn't start or even try to start- hmm....

Anyway, I decided to recheck my work and all was confirmed so I gave it another try and still nothing. Hot spark at the plugs-yes; gas in the carb-yes, air thru the intake-yes. So, ok, I set #1 on TDC on the compression stroke, aligned the rotor on #1 on the cap, and checked the front pulley and pointer for the timing marks-no timing marks?

Hmm, what now? So I spun the fan around and found the timing marks on the pulley roughly 140 degrees from where they should be-that can't be right?!

Anyway, I am happy to report that by moving all the plug wires sequentially around on the cap, I finally ended up with a running engine again, with #1 wire positioned where the #3 wire is supposed to sit, according to TM9-8030. So I have two questions for the group:

1. Isn't there a specific pair of marks on the oil pump and camshaft gears in order to properly align the distributor tang for timing purposes?
2. Is it possible that someone just removed the front pulley then bolted it back on in a different position-hence throwing off my timing marks?

I must say this one challenged all of my mechanical knowledge, and has worked out on a positive note for the short term, but I may have to go in an redo the oil pump if, indeed, there are alignment marks that my predecessor missed. That will be down the road-I still have to finish stripping and painting my cab interior.

Any and all replies are welcome-what do you think?
Thanks!
Gary

[Lifer]

No marks that I'm aware of. The "secret" is to make sure the engine is at TDC on the compression stroke, remove the cap and watch the rotor turn as you pull the old one out, position the rotor to that position on the new one and watch it turn as you slide it in. If all goes well, it should end up at the 7:00 o'clock position when the pump is all the way in. If it's not, pull it back out, back it up a tooth, and put it back in again. You may have to do this several times to get it right.

[MSeriesRebuild]

As many of you know, I run a 12 volt system on my M37, to include a civilian distributor and oil pump. Well my wife finally talked me into getting a new distributor because the old one was completely worn out. The new distributor (civvy) arrived late last week, is an exact match, and I installed it exactly as the old one came out, noting the rotor position, plug wires-to-cap, etc. To my great surprise, after install it wouldn't start or even try to start- hmm....

Anyway, I decided to recheck my work and all was confirmed so I gave it another try and still nothing. Hot spark at the plugs-yes; gas in the carb-yes, air thru the intake-yes. So, ok, I set #1 on TDC on the compression stroke, aligned the rotor on #1 on the cap, and checked the front pulley and pointer for the timing marks-no timing marks?

Hmm, what now? So I spun the fan around and found the timing marks on the pulley roughly 140 degrees from where they should be-that can't be right?!

Anyway, I am happy to report that by moving all the plug wires sequentially around on the cap, I finally ended up with a running engine again, with #1 wire positioned where the #3 wire is supposed to sit, according to TM9-8030. So I have two questions for the group:

1. Isn't there a specific pair of marks on the oil pump and camshaft gears in order to properly align the distributor tang for timing purposes?
2. Is it possible that someone just removed the front pulley then bolted it back on in a different position-hence throwing off my timing marks?

I must say this one challenged all of my mechanical knowledge, and has worked out on a positive note for the short term, but I may have to go in an redo the oil pump if, indeed, there are alignment marks that my predecessor missed. That will be down the road-I still have to finish stripping and painting my cab interior.

Any and all replies are welcome-what do you think?
Thanks!
Gary

The bolt hole pattern only allows the crank pulley to mount 1 way, no need to take that off. No marks for installing the oil pump either, likely the reason someone installed it off a tooth or 2. You just have to know how to do it, no problem once you get the big picture in your mind. Since you are not using a military distributor, I'd have to see the one you installed in order to explain the process. In your case it may take pushing the pump in a couple of times to hit the correct combination, not a big deal though since it is located outside the oil pan. If you can get the timing set on 4 degrees BEFORE TDC, you will be ok until time permits straightening out the error.

[Captnsim]

That about sums it up Lifer. TDC is key.
Real easy to get the dist in wrong during that initial insertion.

[T. Highway]

I learn a little something every day that I read posts here, but it always leads to more questions.

Please explain, and keep in mind that I am completely new to these engines.

Cal_Gary wrote, As many of you know, I run a 12 volt system on my M37, to include a civilian distributor and oil pump.

My question is about the civilian oil pump.
I want to keep running the military distributor and a 24 volt system. I've read that a higher pressure / volume oil pump was available, but I've been told these are for non-military engines. Why is that and are they misleading me?

[Lifer]

Hmmm! Higher volume/pressure oil pump? News to me, but then, I keep learning stuff all the time, too. If I keep this up, I'll be an idiot savant who doesn't know a durn thing about nuthin' but M37s.

[MSeriesRebuild]

Once upon a time there were high volume oil pumps, may still be some around, never saw a high volume pump with the military spec shaft though.

The reason this whole thing is somewhat confusing, the civilian oil pump shaft is designed with a centered drive groove for the civilian centered distributor shaft drive tang. The military distributor's shaft has an offset drive tang, thus must mate with an oil pump shaft that has an offset groove so it turns on center and true. The offset specs were military only and were designed so the distributor supposidly could not be installed 180 degrees out of time, however it doesn't take but a little pursuation to install a military distributor 180 out in spite of the offset design. Long story short, the offset design only works for installers who use good common sense when doing the installation, otherwise it's easy to still do it wrong.

[T. Highway]

Thanks Charles, Now I understand.

[Cal_Gary]

Thanks for all of the replies, Gents! Your information is most helpful, and I will tackle the oil pump alignment some time down the road. I will say that my scratch-timing has awakened a lot more power in the 230 that I didn't expect (so you can just imagine how totally shot my old distributor was). Anyway, I posted the flag yesterday on the right-front to honor all who have served.

Now, back to the interior stripping and painting....
Gary

[Lifer]

And a heartfelt "Thank you!" from all the veterans in the Lavonia, GA area.