The Stovebolt Site Forums The Shop Area Engine Shop Rough Idle after installing 235 Petronix

Installed a Pertronix ignitor along with their 40kV 3.0 ohm coil in a 235. Advanced base timing 2 degrees and left spark plugs at .035. I'm happy with the performance with one exception. It is a little rough at idle, not super bad but not 235 smooth either. The vendor I acquired the parts from stated there was no reason to replace my solid core wires. Their reasoning was, they have sold hundreds of these units used with non-suppression wires without a complaint. Whatever that means.

I would appreciate anyone's opinion.

RUN- - - -do not walk away from anything with the Pertronix name on it. Those systems come in two types- - - -the ones that have failed, and the ones that will fail soon. One of our long term members has done a forensic analysis of the circuits in a Pertronix system, and he has nothing good to say about the product at all. Solid core wires have no business whatsoever on ANY ignition system, except maybe an all-out racing setup. They promote rapid failure of distributor caps and rotors due to overcurrent. If you're looking for a good fix, the most common suggestion you'll get on this forum is "Trash the junk and install a real electronic ignition like a General Motors HEI system!"
Jerry

I heartily second what Jerry said. He may be talking about me. I deconstructed one of their epoxy-molded "ignitor" units (given to me by a friend after it failed miserably). Carefully took it completely apart. There might (and I emphasize the word might) be something like $3 to $5 worth of stuff in there and that's it. A Hall Effect sensor and a magnet with 8 segments that fit over the distributor lobes. A resistor or two. That is your "ignitor" in a nutshell. Something a jr. high kid in a science class might invent. In my opinion this is a horrible excuse for an ignition product and a tragic ripoff. The FACT many people carry a points distributor under their seat (and suggest everyone do this) when they travel should answer any questions about dependability. Think of it this way: let's say a new type of tires was being sold which promised to make your truck drive really nicely at any speed but they cost a lot more money. And there were scads of people (just on this one site) who said "okay, buy them if you must but never leave the house without carrying 4 normal tires so you can get home when those fail." Would you feel good about buying them?

A year or year and a half ago I showed exactly how to convert one of the Chinese HEI distributors made for the Chevy 230-250 for use on the 235. It will cost you about $100 or less to do this, includes the matched coil and you only need a hacksaw, a bench grinder and a collar to attach to it. Even though it was made in China and even though it is ugly, you can use GM components in it and even with the Chinese parts I promise you it will be more dependable than anything labeled Pertronix. I'm using one of those on my truck right now and it is just fine. I bought it in 1997 and have had no trouble with it.

Good luck! You can get the Chinese distributor in three colors...black, blue, red. Attached is an image (note you get a brand new vacuum advance canister, too)

I myself am not a Petronix fan. It’s not a high performance ignition. It’s just a different way to trigger the points. So for starters, if your 235 distributor is not up to snuff, the Petronix will not help you, with or without the coil that Petronix recommends. So you need a distributor in excellent working order, not just working, but working to specification.

And if the module fails, and quite a few have, you are stuck so you better have a spare module and tools, or a spare point distributor ready to stab in place of the Petronix.

But let’s just say you want something a little better. HEI ignitions are really hard to beat. Unbelievably reliable and a spark that will blow your socks across the room. Really one of the best factory ignitions ever developed.

Tom Langdon had an excellent conversion but they are no longer available.

Davis Unified Ignition (now Performance Distributors) has a good one. Pricy, but good.

https://performancedistributors.com...1-ci&attribute_pa_color-choice=black

You have Jon G’s above conversion,

also Deve’s conversion.

http://devestechnet.com/Home/HEIgnition

Probably others. But if HEI is not what you want there is an alternative.

Use your stock distributor (in good performing shape) with an MSD 6A or 6AL (the L is for rpm limiter). The MSD unit is what fires the plugs and is a true performance unit. The points trigger the MSD so no voltage through the points so hardly any wear and tear on the points. Years before you would see any wear. Use an MSD blaster coil, or Accel Superstock (black, yellow or chrome). Easy wiring, multiple sparks at idle and through the rpm range until it reaches critical mass and is one big spark. You can hide the MSD, paint the round coil black, and if the MSD ever fails, just swap a couple of wires and you are back to a points ignition. Way better than a Petronix.

This company will convert your dizzy to HEI.


Converts your original points style distributor to HEI system

DAVE's small-body HEIs
24 Buffalo Lane
Yerington, Nevada, 89447
775- 722-3294
[email protected]
http://www.davessmallbodyheis.com/

Everyone's input is much appreciated. The last thing I need on the first road trip ( with my wife in the seat) is a ignition failure! I'll run with the Pertronix in the hood but before I hit the road it's going to be HEI.

This question is going to sound like a smart-arse one, but it’s not meant that way at all….

What exactly is the problem we are trying to solve with Petronix or HEI? Am I really missing out? I’m in the camp that Pertronix is a lousy solution even if we are talking about a non-existent problem. But I’m willing to entertain the idea of an HEI upgrade if it’s really an upgrade.

My 12v points setup starts easy, runs well, etc. But I don’t really have a basis for comparison. Maybe HEI would make it start and run even more better-er

I suppose that points ignition requires some maintenance, in theory. My truck certainly isn’t a daily driver but it gets driven pretty regularly other than winter. I probably throw the dwell meter on it once per year just to verify my gap is still ok. And it basically doesn’t ever change.

Without more input from you all, the only real problem from my seat is the growing lack of quality replacement points/condensers. Jon G has the condenser problem licked. I have been buying and hoarding NOS Delco Remy points sets. Haven’t even had the occasion to use any of them. The parts-store points and condenser in the truck are going on a decade old now.

I'm with you JW51. All of my vehicles have points except the Ford trucks. The Cadillac has been my primary vehicle for 23 years and nearly 200,000 miles and I've never had any problems associated with points.

I have installed Jon G condensers in all of them after recent condenser failures in two vehicles.

There are in my opinion at least 3 advantages to a well designed HEI system (and I do not include Pertronix in this at all): more consistent spark, hotter spark output and your coil will run somewhat cooler and last longer. After the startup and consequent inrush of electrons, amperage needed by the coil will decline. Added to that the HEI scheme will let you run a wider gap on your spark plugs, your plugs will last longer and if your results match mine, combustion will be improved...it is a more energetic spark, after all. A leaner running carburetor can be used, also. That ties in with the whole idea behind the HEI change...leaner fuel is by nature less optimal from a combustion efficiency standpoint and the HEI system was effective in burning that fuel and causing less airborne pollution. You may notice one change if idling your truck in a garage. It won't smell as bad because you'll be burning more of the air/fuel mixture...which some will say extends the life of your exhaust system (although I think relative humidity and where you live is equally as much of a determining factor). You will also notice hotter exhaust gasses...holding your hand in front of your tail pipe things are going to feel hotter back there. I'm not saying all the smell of unleaded fuel will disappear. It won't but it certainly won't be nearly as overwhelming.

I'm not against points at all...not in any way. They're just fine and I am always trying to think of ways to improve their effectiveness. But just like HEI there are some limitations. I am and have for a year been considering a coil-on-plug system for the Stovebolt engines. What's the advantage there? There are a few. One is that each coil will fire after a longer resting time interval...a big positive. But unlike HEI which can easily be adapted, this is more of a technological swamp. And I'm not convinced the old inline 6 will benefit from this technology as much as I had once hoped.

Thanks, Jon. That helps. I was genuinely trying to learn something and not be a smart-arse.

Did you tune your carb leaner when you made the switch?

Well, sort of but without any jet/metering rod alteration. I'm using the YF 3211S which was the last carburetor Carter made for the 235. Jon H and I talked about it and he suggested adjusting the float to cause it to run a wee bit leaner (the 3211S runs leaner by design as GM was just starting to consider ways to limit smog in bumper to bumper traffic).

Just to add to the confusion....... I have been running the Pee set up for years now and installed in a few friends as well.... and we are still friends.....but...... we must be in the minority group that is still using them without failure..... all of the onstock 216 rebuilt and 261 rebuilt.......261 RUNNING YF CARTER SUGGESTED BY JERRY AND LOVE IT.....

Our experience is that you have to readjust to a slightly leaner mix, get rid of the hard wire spark plug wires and increase the gap on the AC 43 to about 39 to 40 t and then it purrs. Also converted to paper filters in an original air filter casing.

The MAIN reason....and a very important one for us...... the distributor is literally inacessible on the CMP trucks with the British design semi cab over...... in my case space was so tight that I had to change the 261 dizzy for the smaller dizzy from the 216 Pee to gain about 5/8 of an inch .....so 4x4 driving on abandoned logging roads with no service (cell or otherwise) is critical on Peesystem.... set it once and forget it..... Maybe we have been lucky....... accessing my engine is about 3 hours to remove every bolt and screw holding the 5 panels of the engine cover...same to reassemble.... may be more as you have to use pry pin bars....instal loosely...drive it a little and retighten each fasteners.......... my hood opening is about 12 inches wide by 20 inches long......only used to add oil!!!!!! or check the rad....

Now I have something else to worry about!!!!!!

Bob C

DEFINATELY NOT a pertronix fan, however:

If you really wish to use one, upgrade the generator to an alternator to cure idle issues (before the unit fails).

Jon

Wow! That seems like an absolutely horrible design for a military vehicle. Usually you'd expect simplicity and quick change modifications rather than the other way around. What were they thinking?

I have had Pertronics units and have worked on various vehicles with them. I'm not pro or con about them.
I do know that they specifically say not to use solid core wires. I believe that all of the electronic
ignition systems I am familiar with specify resistance type wires.
Fred

One gripe I have about the Pertronix systems I've worked with- - - - -the trigger assembly that slips over the cam that normally would operate the points is a VERY sloppy fit- - - -which could, and probably does result in a degree or more of variation in spark timing between cylinders. This problem could very well be the source of the rough idle the OP mentions. That error would also be totally random- - - -no way to adjust it out for a more accurate spark. If someone insists on running that ignition system, I'd strongly suggest gluing the trigger onto the cam assembly with some sort of stuff like epoxy or LocTite. Of course, that would make an emergency swap back to points in case of a breakdown extremely difficult.
Jerry

It sounds like the Pertronix set up for the 235 is a lot different than what I've had experience with. I've had a Pertronix unit on my 69 Camaro SS396 for about 10 yrs. It hasn't so much had a hiccup. I drive it regularly. I have found people either love or hate the set up.

Reply to Otto

Calling the design of my engine bay as "horrible " is a compliment. Historically, late 30s just before the war, the British prepared the specs and then went to their colonies to see who could make them. Canada responded with a joint effort from Ford and GM to come up with a truck that they could both make with as many interchangeable parts except for the engine, axles, tranny. So hamstrung with British engineering technology of the stone age they built what I have.....one example of "horrible".......the cab is to tight, to drafty, too hot, too noisy and absolutely unserviceable withi run flats and no spare tire/wheel....... right hand drive.....and the pedals are clutch on the left, throttle in the middle and brake on the right....... and the foot well is so narrow that I can't drive it with safety boots.....
So Model 11 was produced for 9 months , April 1940 to end of Dec 40, model 12, with some minor modification in 41 to early 42......and then the British having lost most of the early new trucks when they got pushed off the continent came back with large orders by the 10s of thousands....... Ford and Chev would agree to producing the larger orders BUT only if they could modify the design to reflect combat/field results and to align better with North American production processes...so cab model 13 came about and were manufactured by the 100s of thousands for Australia, New Zealand, and lend lease for Russia. My 3/4 ton truck as a GM 3 ton rear axle is a brute to drive, weighs in at 5800 pounds, to carry a load of 15 cwt or 15 times 112 pounds..... BUT I love it.

On one side of the engine I have 1/2 inch clearance with the smaller dizzy cap of the 216 mounted on my 261...on the left side I had to remove the PCV connection on the manifold and relocate to a home made a 3/4 in. spacer between carb and manifold, drilled for the PCV, Wipers and my vacuum gauge..... leaving me with 3/4 clearance for the engine cover .....said engine cover is insulated with 1/4 ceramic felt to keep passengers from burning their right knee........ on hard runs the exhaust manifold glows a faint cherry red a mere 3/4 inch from the sheet metal engine cover..... spectacular at night....

Bob C