I'm back again with a new question, after many hours of diagnosis and thinking I might know what my problem was/is. I originally posted a question about whether my distributor was the problem because I had an erratic dwell. https://www.stovebolt.com/ubbthread...-need-a-new-distributor.html#Post1422088 I'm starting a new thread because that one strayed well away from the original question.
I'm working with a 1949 216 that I believe is 100% stock (still 6V) and has a Carter W-1 carb. After looking more closely (and using my brain!) I realized my distributor is just fine. The shaft internal to the distributor has almost no play. The distributor moves around in the engine block a little, but not much. That was definitely not the problem causing my erratic dwell. As I was in the process of diagnosis, the truck got to where it wouldn't even start. So with the help of my son, who's a Peterbuilt certified diesel mechanic, we diagnosed everything possible related to the ignition system and concluded it must be the condenser. I was very reluctant to believe that could be the problem because I had one of Jon's new design condensers installed. Today I went and bought a "Blue Streak" condenser at the FLAPS and after installation, she started right up with absolutely no other changes. It ran great for about 15 minutes while I adjusted the timing, checked the dwell and adjusted the idle. I went to clear everything from around the truck so I could take my victory lap around the neighborhood, and it died before I could get back in the driver's seat. It won't start again. This is now the second time I've had the truck running really well, and it just dies after about 15 minutes and won't start again. Almost exactly the same scenario each time, months apart. I assume it must be the condenser yet again.
Is there anything that could be damaging my condensers? It wouldn't seem so, but it's hard to believe I've now had 2 condensers that only lasted about 15 minutes out of the box, including Jon's.
Heat and/or overvoltage will kill a capacitor. I would rule out engine heat for now. The condenser and coil work hand-in-hand. Talk to your son and see if he can get access to a diagnostic scope. Install another new capacitor. See what the primary and secondary coil voltages look like.
Last edited by buoymaker; 09/10/202111:31 PM.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
I’ve experienced heat sensitive bad coil before and it took a lot of careful observation to diagnose but once observed was so obvious in hindsight Good luck and let us know your testing progress -S
Change the coil. If there's a short circuit between the primary and secondary windings, the condenser will get hit with tens of thousands of volts every time the points break. That will blow holes in the dielectric of the condenser, and short it out in a matter of minutes, causing the engine to stop. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Thank you guys for all the great suggestions. You wouldn't believe how frustrating this has been... or maybe some of you would.
I've asked my son about the diagnostic scope. He was actually telling me about the capability to graph voltages the other day. Not sure if he'll be able to swing that.
I didn't mention this before, but when I first had engine problems 6+ months ago, the first thing I did was replace the coil with a new 6V coil from Napa. When that didn't fix the problem, I did the full tune-up, using the condenser from Jon, and the new coil. That was when the truck ran great for 15 minutes the first time.
My son tested the primary/secondary resistance of both coils the other day and they were pretty close to the same. This was on the workbench, not while in use or in a warm/hot environment. Short of having the scope, is there a better way to test a coil?
Now I'm wondering if my original condenser went bad, causing my initial problems. And the new coil I installed is also bad, killing both condensers I've used since putting it in.
If I can't get the scope, I'm thinking I may go back to using the original coil with another new condenser and see what happens.
A resistance check will not show up a high voltage pathway between the primary and secondary windings. It's basically a hole in the insulation that allows a spark to jump beteween the two windings. Early HEI systems for the odd-fire Buick V6 were notorious for burning a hole in the distributor cap under one of the coil attaching screws and making one cylinder miss intermittently. It was impossible to duplicate on a scope unless the car was on a chassis dyno so the engine could be loaded in the shop. The repeated flashover would cause frequent failures of HEI ignition modules. GM solved the problem by making the cap thicker in the area that was prone to burn-through. One cause of burn through on a conventional coil is a dangling plug wire that allows the secondary voltage to go to 25-30 KV or more without firing a plug. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
I totally forgot the basic first step. With an analog meter, do a resistance check, at X1 scale, to see if you have a sweeping deflection (meter movement) as the condensor charges. If the condensor is open, no deflection.
Last edited by buoymaker; 09/11/20212:57 PM.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
I totally forgot the basic first step. With an analog meter, do a resistance check, at X1 scale, to see if you have a sweeping deflection (meter movement) as the condensor charges. If the condensor is open, no deflection.
Unfortunately I don't have an analog meter. I found a procedure for testing with a digital multimeter, but I'm not confident it actually works.
Regardless, I figured out what the problem was this time, without any doubt. I was about to say $#!= it, after installing yet another new condenser and getting no start, when I decided to re-check a few things with my meter. I immediately discovered that the hot side of the points were grounded. What the heck?? I had used a piece of rubber to insulate the stud coming thru the side of the distributor and apparently after it got hot, it allowed the stud to short to the base of the distributor. Obviously no fire with this situation. I put a nylon spacer on the stud outside of the distributor and re-checked everything. All good and the truck fired right up. I took my victory lap around the neighborhood successfully, came home, shut it off then restarted. It's going to take a few successful runs before I'm confident, given what I've been thru, but it all seems good.
The question now is whether this was my problem all along. There was a cracked bakelight washer on that stud that I replaced with the rubber. It looked like it would have worked as an insulator, but now I'm not so sure. Was it shorting after getting warm? After my frustration wears off, I may go back and try the 2 condensers, and the old coil, all one at a time, to see if in fact any of them are bad. I'm not so sure now.
That distributor housing insulator is available, but you'll need to search some antique farm tractor websites. Farmall, Oliver, and a few othes used Delco-Remy distributors, and the insulators are identical to the ones used on stovebolts. Our local "Tractor Supply Co. " in middle Tennessee has them on the shelf, in kits that include the threaded studs as well, along with points and condensers that are a direct swap with stovebolt sixes. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Just closing this thread out... Finally got a chance to re-check things. Truck has fired right up each time I've tried it with the 2nd Blue Streak condenser I installed, after I fixed the distributor short. Today - after starting it first as a baseline - I re-installed Jon's condenser to test it. No start. I checked with the meter to verify I had no shorts. So apparently that condenser is bad. I reinstalled the Blue Streak condenser and she fired right up again.
That distributor housing insulator is available, but you'll need to search some antique farm tractor websites. Farmall, Oliver, and a few othes used Delco-Remy distributors, and the insulators are identical to the ones used on stovebolts. Our local "Tractor Supply Co. " in middle Tennessee has them on the shelf, in kits that include the threaded studs as well, along with points and condensers that are a direct swap with stovebolt sixes. Jerry
I’m glad I stumbled on this thread. Jerry, thanks for the info, I had read that these were not available.
Is this the correct one in his link? It looks like it to me but wanted to be sure.
The eBay link works. You just have to copy it and drop it into your browser. It just doesn't work if you try clicking on it. Also, glad to hear these are available. Mine on my 54 is a little questionable. It is sloppy/loose from wear. I might proactively replace it before I have a problem.
2 things are going to kill your condenser (which is really just a capacitor)...too much heat or too much voltage (really common with a bad coil). If you run one above its intended temp range, it will degrade rapidly and failure will be guaranteed. If you feed it too much voltage, you'll ruin it by damaging the dielectric layer. A dead short with high voltage will also kill one, but that's not so common in a distributor (although by no means impossible). The other two things can happen, however. That's why I worked so hard to find components that were rated for high temp and a higher voltage. But any electrical component can fail.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
