Jeep prestolite distributor problems

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sccachallenger

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Ok, not a Mopar at birth, but many of us aren't either:)!
My wife inherited a '69 CJ5 with a V6.
I got the engine unstuck, after 30 years of slumber.
Got the engine running but no spark to cylinder number one.
Swapped wires around but still no spark, compression good in all cylinders.
Timing light confirms nothing coming from the distributor.
The cam that operates the points doesn't look symmetric.
Wondering where to get a good new or used one?
Anyone ever have a similar problem with a points distributor?
 
You may have a worn out lobe on the distributor cam. If so, get another distributor, or, if possible, the cam section. Check with a local Jeep club, Ebay, Craigslist, etc. Remember to properly lube the replacement.
 
Depending what you mean by the dist cam looking "symmetric", remember if this is the old odd-fire Buick V6, it isn't made to fire the plugs at even intervals...
Sounds more like a bad cap if you're not getting fire out of #1 terminal, but the rest fire...
 
sccachallenger said:
The cam that operates the points doesn't look symmetric.
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Crank the engine with the cap off watching the rotor, to see if it appears to wobble, which probably indicates a bent shaft.
Also watch to see if each of the corners on the hexagonal point-cam has to open the points a similar nearly identical amount.
Also if the #1 plug is shorted, the timing light may not strobe. So replace the plug or swap in one from another hole, and see what happens.
I know nothing about Buick V6s except that the very early 3800s ran like crap. By crap, I mean very rough.
The much later 3.8s are miles different engines. Smooth as silk,powerful,quiet, and my 2008 Allure/LaCrosse occasionally got 40 plus mpgs on the hiway. That was probably the single most reliable car I ever had; too bad it got written off by some texting-while-driving ................. person.
 
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Some random comments:

1...Points are easy. Make certain the points are electrically opening and closing, in other words check them with a dwell meter with a "points resistance" scale, or check them with a multimeter

2...Breaker points systems MUST have a good "condenser." (Capacitor). New does not mean good.

3...Check for obvious wear and slop and out of true with the cam and shaft

4...BE CAREFUL. Those old girls had a special dist. setup for the odd-fire V6. If you look at the points cam, you will see the cam is NOT symmetrical. Every other pair is shorter or longer depending on how you want to look at it. If you have the correct cap---and there were several----the towers are also paired---two closer together and two further apart. YOU CAN NOT rotate the plug wires one hole to get it in time. The thing MUST be installed "as per" to get the pairings correct.

5...Of course don't discount it could be a bad coil. You can check it by rigging it up with clip leads so:

"Rig the coil with clip leads so you have power to coil + and at coil - connect the dist. condenser, and clip the ground side of the condenser to battery ground. "Rig" a coil wire and test gap to battery ground---not the coil case. It is wise tho, to ground the coil case to battery.

Now take another clip lead connected to coil - and tap it onto the battery ground post. Each time should produce a "snap" single spark Of course the condenser must be good, as well
 
Professor Fate said:
Depending what you mean by the dist cam looking "symmetric", remember if this is the old odd-fire Buick V6, it isn't made to fire the plugs at even intervals...
Sounds more like a bad cap if you're not getting fire out of #1 terminal, but the rest fire...
Click to expand...

EXACTLY this
 
The old style 225's use to rattle apart dist. advance mechanisms and tear up cam drives. This was back in the day many engines had the much hated nylon top sprocket---they are not gears. They were a great Jeeper engine, tho, lots and LOTS of bottom end

"Back in the day" when we had "real" parts guys working in real parts houses.......we had REAL paper catalogs, one was a "numerical interchange." You could take the tag on one of these dist's and look up all the internal parts right out of the interchange--and KNOW that you had the correct cap

We once had a customer come in with one of these, had the cap on there with rubber bands. I said "why?" "Can't find the right cap" says he. I told him next time he was doing something in there, get the tag no. and come back in. He thought I was a hero. I was just doing my job. I AMAZED ME THAT WITH COMPUTERS that parts stores of today can not do this. Oh'really's has no clue.
 
Many thanks for helping me think through this!
I'll report back what happens. The replacement cap matched the fit and post spacing of the one I took off.
Never occurred to me the weird looking cam might be the way it was made!
 
Not to steal info time from original poster but what makes it an “odd fire” v6? I’ve heard the term but never got to work on one in my 50 years.
 
Because of the way the crank is made, they did not fire at exact 60 degrees. The newer "even fire" had the crank rod throws offset. The old crank had paired rod throws just like a V8, the odd fire has the rod paired throws ground offset.........see if I can find a photo...........here we go...........

main-qimg-fb5c0576c699c96a6025a4320a01951f.png
 
67Dart273 said:
Because of the way the crank is made, they did not fire at exact 60 degrees. The newer "even fire" had the crank rod throws offset. The old crank had paired rod throws just like a V8, the odd fire has the rod paired throws ground offset.........see if I can find a photo...........here we go...........

View attachment 1715591809
Click to expand...
Thanks!
 
At idle they shook pretty bad. I had a guy come into the shop one day in the early 2000s to have the idle-shake checked out. That's when I learned about the 3.8.. My boss lost money on me that morning,lol. But they do have an interesting idle out the tailpipes.
 
The best way to fix a Prestolite distributor on a Jeep Dauntless is to replace with either a window-cap Delco or an Odd-fire HEI.
Have you been to the www.earlycj5.com forums?
 
C130 Chief said:
The best way to fix a Prestolite distributor on a Jeep Dauntless is to replace with either a window-cap Delco or an Odd-fire HEI.
Have you been to the www.earlycj5.com forums?
Click to expand...

A Delco is not much better. The 225's rattle the hell out of advance mechanisms, and the cap availability on the Delcos is not much better than Prestolite. I will say, it is likely parts are a bit more available.
 
67Dart273 said:
A Delco is not much better. The 225's rattle the hell out of advance mechanisms, and the cap availability on the Delcos is not much better than Prestolite. I will say, it is likely parts are a bit more available.
Click to expand...
The HEI choice, makes me wonder how tight it'll get up there. Looks like I may have to move a fuel line, not sure what else. I haven't even checked to see if the vacuum advance works on the prestolite.
 
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AJ/FormS said:
Also if the #1 plug is shorted, the timing light may not strobe. So replace the plug or swap in one from another hole, and see what happens.
Click to expand...

Well I tried swapping plugs first, cause it was the easiest thing to do, and Bingo, that's what it was!
I didn't realize the timing light wouldn't flash if the plug was bad. So thank you AJ!
It still seemed a little rough so i lowered the idle speed, and adjusted the mixture screws.
Wow what a difference! Still got a long list but great to hear it run!
 
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