Technical POSSIBLE IGNITION ISSUE - 235 I6, 6 Volt Pertronix

So on my way back to work today I began having an issue on my 54 Bel Air, that I suspect to be a transmission issue.
I was running 55-60mph, and it began to 'pull back' for lack of a better term, maybe slip would be a good term. Almost like a trans that cant decide between low or high gear.
It felt like someone who was all in on the gas pedal, and let off, back in, let off. It would do this continuously.
Naturally, I thought I was out of gas, or beginning to be. I filled the tank (only took 7 gal.)
Cranked for a good while, and fired up. Revved strong.
This is a 235 I6 all factory engine.
Checked ATF at the gas station, looked SLIGHTLY low, not much at all.
Any ideas? Trans fluid was done like 6k miles ago, and the old stuff looked fine, new stuff looks OK. Has a leak at the cooler line, but its slow. Nothing under the vehicle prior to, at the gas station, or sitting here at work.

 

Is the rpm changing? As in if it's slipping the rpms would raise and the car would slow down. Is the car maintaining speed and the engine is changing rpm ? I know it's all seat of the pants feel and hard to explain.

But it sounds like fuel or fire problem to me, gas more likely, flooding out, gas pump getting weak, fuel filter plugged etc.... at least to me. Then maybe fire, bad capacitor, coil overheating etc...

Without actually driving it personally it's hard to tell....

....

 

Ill have some time this evening to diagnose more. Honestly it doesnt really feel like RPM is changing, but more like someone pulling an e-brake. Car will take a slight nose dive. Ill have to take it up to speed, let it happen and put it in neutral. Now that I think of it, when I rolled up to the pump I had realized the engine was off, which is was not a few seconds earlier.

 

Transmission or fuel delivery issue?

 

We had a '65 w/265, cast iron PG, that wouldn't shift out of first suddenly. Turned out to be a broken rotor in the rear pump.

 

Yes, those had 2 pumps in them. I would expect a pump issue. See if this helps at all.
https://www.567chevyclub.com/images/56_Chevy/powerglide.pdf

I'm driving a '66 Belair I just picked up with the later PG. It had the standard flare on the 1-2 shift, it was a quart short on fluid, added some and it is worlds better. I doubt this is your problem.

 

I’d be going for engine (fuel/ignition) if it feels like “it’s taking a slight nose dive”. Transmission I think would just be like coasting or revs rising with no change in speed or you’d know it was jumping between gears.

 

I am beginning to lean towards something in the dual diaphragm fuel pump failing, or some sort of fuel vaporization issue. This happened at the hottest point in the day and the car is not garaged. Personally I am not sure Ive driven it on a day warm as this. The fact it cranked for 30 seconds then fired, tells me the fuel in the lines was possibly vaporized, waiting on new, cooler fuel. It did not do it on the way home (about 10-15 degree difference) and did not do it this morning (about a 25 degree difference from yesterday around noon-1pm). Someone has replaced the main fuel line, and it is close to the block between the t-stat housing and valve cover. I think I will move that and throw some wooden clothes hanger clips on it, see if it does it again.

 

And now that I think back - I pulled the air cleaner, looked down the carb (engine off) and ran the throttle linkage a few times and saw no fuel - just some 'steam' (fuel vapor?). Possibly my issue. Luckily in my short years of old car ownership, heat syncing the fuel lines has never been an issue. So this may explain my greenness/confusion with the issue.

 

Update: I did not have the issue for a few days, and then randomly on a cool night I began to feel it 'surge' again, only around 55-60. Less than, no problem. Started to really do it around 55-60 pretty harsh, so I shifted to neutral and I would still hear the engine RPMs kind of fluctuate. It then 'popped' (through the carb?) and died. Coasted, cranked for a minute, started and ran fine. No issue again on the way home, mainly stayed under 35MPH (my neighborhood speed limit). Nothing visibly wrong, oil pressure never faltered, AMP gauge seemed fine, never overheated. WTH!

 

I grew up riding in the back seat of my grandparents 54 Chevy two door 210 with a glide and if they aren't abused the trans doesn't give a lot of trouble.
That said, quite often old cars that ran fine tend to act up when you change something. What have you changed lately that might affect fuel delivery or ignition?
Where did you buy your last tank of gas? I only go to high volume newer gas stations and unless I don't have a choice never stop at those 70 year old gas stations turned mini marts that still have the old tanks.
The double action fuel pump has one side for pumping fuel and one side for vacuum for the wipers. Meaning if it is working right the wipers still work on acceleration or pulling a long grade. That is why the "double" part.
If it is "vapor locking" it is probably in the line from the pump to the carb as that is the only part of the fuel line from tank to carb that is exposed to heat on a 54 with a stock six. A cup of ice water poured on the fuel pump and fuel line will usually be a momentary cure for that though. It will also tell you if that is the issue. My son and I used half a cooler of ice water on my 48 when I had the 283 in it and we were pulling a long grade out of Green River Utah towing a 16 ft U haul trailer. We made it about a half mile at a time up that grade before it acted up again and it never vapor locked before or since that one grade in 100+ heat.

 

I honestly havent changed anything on the car in about 4,000 miles. Just drive it. Pertronix Ignitor, Coil, tuned carb and timed motor, and swapped to better battery cables 4k ago, but nothing since. I only fill up at my local Sunoco which is very high volume. I am wondering if its the Pertronix, I ordered another set and coil and will use that to diagnose.

 

If I read this thread correctly, you looked down the carb throat after and episode and saw no fuel from the accelerator pump so you ordered a new coil? How about checking the fuel pump. It should be able to pump to maybe 4 - 5 psi, deliver a pint of fuel in 30 seconds, and pump up and hold a vacuum on the inlet side.

 

Are you running a generator or alternator?
I’ve heard that the pertronix don’t play well with a generator

my thoughts with regards to a slipping transmission is it would slow down but not nose dive like you described

 

Correct - but keeping in mind this was at a gas station with a quick look, no flash light. I ordered a coil to have on hand if I feel the ignition is dropping out.

 

Generator. I hadnt heard that before, but this is a 6 volt system with the intended Pertronix, no changes noted on ammeter when this issue occurs.

 

Put your point set back in. That’s all I got.

 

I think if you were to look at the charging system outputs of a generator and an alternator on an oscilloscope, you would find that the DC generator produces a "dirtier" output signal. And I wouldn't be surprised that an older mechanical voltage regulator might only make things worse.

Years ago Direct Connection made an electronic ignition conversion kit for older points style Mopar distributors. Their installation instructions called for a solid state electronic voltage regulator to be used in place of the mechanical regulator used in their earlier model vehicles. Their electronic ignition required a clean, stable voltage supply. This was to prevent early failure and erratic operation of the newer electronic ignition conversion systems.

Years ago at least the upgrade was simple and not terribly expensive. But I don't know if there is a similarly simple way to do this kind of conversion to a 6v D/C generator set-up.

 

Would this make sense though, given I went many thousands of miles with no issue on this setup? All that ever changed was fuel and engine oil.

 

Maybe not necessarily. I just put it out there as one possibility as to why the ignition is failing, or has failed. Did the Pertronix have only 4,000 miles on it? It should have held up better than that.

I'd go back to looking at the carburetor as well. It sounds like there is no accelerator pump shot, from your description. If it's a Rochester model B also check that the two big phillips head screws that come up from the throttle body into the bottom of the float bowl are tight. Wasn't uncommon for them to work loose over time. The gasket between the throttle body and float bowl may have deteriorated as well.

 

Have you tried the "hand over the carb until it nearly dies" trick? I had some small bits of crud in the carb, and it was idling funny, take the aircleaner off, hold the throttle at about 1500 RPM, choke it with your other hand until it nearly dies, remove your hand and let it build up RPM again. Do it a couple of times and it clears the crap out.

 

I have not. May try that next.

 

Update: Tonight I drove it again, to verify this issue is still present (wishful thinking) - it is.
I swapped out fuel pumps (had a spare that came with the car) and the other used fuel pump works. Drove fine, for a little. Hit 45-60 and bam, issue still there. After tooling around the neighborhood for 10 minutes nonetheless.
Pulled the fuel line before the fuel filter, no fuel really until I tipped it down then some came out. Hit the throttle and look down the barrel, no fuel. Smoke/vapor.
Seeing as I dont believe that BOTH pumps happen to have the same issue, I think I am having vapor lock issues. OK. So I have some extra Earl's FlameGuard. Installed that all the way to the outlet on the pump. Issue persists.
Am I missing something here? Should I just make a new fuel line routed way away from any heat?

 

The cause of your problem is contained in the title of your thread.

 

I have been reading that Pertronix will die, not slowly die. Its either working or doesnt work at all - is this not the case?

 

I presume your running a flamethrower thrower coil
is it matched to the module?

I had an issue with mine and the ignition would break down above 2000 rpm and it was because oI had the wrong flamethrower coil. replaced it and problem is gone

also when did your switch to pertronics?

 

Pertronix swap was like September time, and that was before I drove the vehicle a ton. Has been great for those last 4k.

 

Rubber fuel hose collapsing internally ?If you can safely tape a fuel pressure gauge to the windshield,you can tell if fuel starvation is your problem.

 

It’s time to go through the tune up/ troubleshoot list.
Assume nothing.
Fuel......start with the tank, work to the carburetor.
Ignition.....start at the the battery and the switches cleaning/checking connections, work to the plugs
Timing.....Start at the “ marks”......do a compression check.......check/adjust valves......Is the distributor advancing.....
You may have to go through it several times to figure out what has or is in the process of taking a dump.

 

But, did you test either pump?