Gawd I Hate Points, Won't keep a tune Options

[bbrock]

He said in our applications (ACVW in general & T4 specifically) for 90% of the owners he'd never recommend the purchase any of the III products.

@914werke

What was the rationale? Inquiring minds want to know.

I'd bet due to multi-spark feature which really isn't going to work well with a standard coil but I'm sort of quessing.

Very interesting. I went all in and also bought the Flamethrower III coil which I would assume would work well with the multi-spark. I suckered in by the programmable rev limiter though. I'm also curious to know the reps rationale.

[Superhawk996]

He said in our applications (ACVW in general & T4 specifically) for 90% of the owners he'd never recommend the purchase any of the III products.

@914werke

What was the rationale? Inquiring minds want to know.

I'd bet due to multi-spark feature which really isn't going to work well with a standard coil but I'm sort of quessing.

Very interesting. I went all in and also bought the Flamethrower III coil which I would assume would work well with the multi-spark. I suckered in by the programmable rev limiter though. I'm also curious to know the reps rationale.

@bbrock

(IMG:style_emoticons/default/idea.gif) Are you running that Flamethrower coil with the stock points?

From Summit Website:
PerTronix Flame-Thrower III ignition coils were developed for use with the new Ignitor III electronics. They feature an ultra-low resistance of 0.32 ohms with 45,000 V. They were engineered to charge to peak current typically 30-70 percent faster than other ignition coils. This means that maximum spark energy is sustained to higher engine rpm.

Stock coil has built in ballast resistor and is about 4 ohms. You are pulling an order of magnitude more current though the points contacts if you are running points with the Flamethrower. 10x more current will erode the contacts more quickly and/or you could be getting thermal distortion as they heat up.

Just a thought . . . . (IMG:style_emoticons/default/type.gif)

The increased current flow thought the points and coil will also result in more about 10x more induced voltage that the condensor has to absorb. This could be damaging your condensor. Equation for Voltage induced by an inductor is Voltage = inductace (of the coil) x rate of change in the current; V= L(dI/dT). 10x more current = 10x more voltage if steady state current is achieved before the ponts open the circuit.

If the ad copy from the Flamethrower is to be belived, maybe you're only getting 30-70% of that due to other inefficiencies but the math says you would still be getting 3x more currrent flow and induced voltages if we took the 30% peak current with a grain of truth.

Don't want to get lost in the math and electrical theory . . . . use a stock coil if you're not doing so already.

[bbrock]

(IMG:style_emoticons/default/idea.gif) Are you running that Flamethrower coil with the stock points?

No. I'm running a new Bosch blue coil from Pelican

[mb911]

Man sounds like a 123 dizzy in your future. Absolutely love mine and would really suggest it.

[Superhawk996]

(IMG:style_emoticons/default/idea.gif) Are you running that Flamethrower coil with the stock points?

No. I'm running a new Bosch blue coil from Pelican

Give it a quick resistance measurement just to be sure!

[bbrock]

Man sounds like a 123 dizzy in your future. Absolutely love mine and would really suggest it.

Doesn't make sense if I'm going Microsquirt. That will replace both carbs and dizzy with a modern coil pack that will give me everything a 123 has to offer and more.

[bbrock]

(IMG:style_emoticons/default/idea.gif) Are you running that Flamethrower coil with the stock points?

No. I'm running a new Bosch blue coil from Pelican

Give it a quick resistance measurement just to be sure!

Primary is 3.2 ohms. When I installed the points, I first used the old coil from my spare parts bin that was on the engine when I tore it down. It ran fine for awhile but then started misfiring. I suspected the coil since it was the only part in the system not new or refurbished. Bought and installed the blue coil but it did not fix the misfire. That is how I discovered the dwell was drifting. I assume running too hot of a coil would burn the points. No sign of burning on these contacts.

BTW, I re-tuned the ignition last Thursday and drove the car a couple hundred miles. Drove the car 15 miles to a dinner party last night and it was missing and backfiring the whole trip. Haven't checked the dwell yet, but I'll bet it has crept up again.

[mb911]

Man sounds like a 123 dizzy in your future. Absolutely love mine and would really suggest it.

Doesn't make sense if I'm going Microsquirt. That will replace both carbs and dizzy with a modern coil pack that will give me everything a 123 has to offer and more.

Oh yes forgot that was your plan.

[Superhawk996]

(IMG:style_emoticons/default/headbang.gif) Man. This is crazy. (IMG:style_emoticons/default/idea.gif)

So OK on the coil resistance with internal ballast. No burning. Check.

How about the screws that hold in the points plate to the distributor body? All tight?

What I'd really love is to see it curved on an old fashion distributor curve machine and/or hook up an O-scope to it.

What a mystery! Right guy is on the case though! (IMG:style_emoticons/default/aktion035.gif)

One more thought -- do you have the spring in there that goes between the distributor drive shaft (in engine case) and the distributor body / drive cog itself? That spring helps pre-load the drive shaft gear to the crank gear. If not pre-loaded, you would get some random dwell variance depening on gear mesh. Really stretching on theories here . . . ..

[bbrock]

Really stretching on theories here . . . ..

Yes you are (IMG:style_emoticons/default/biggrin.gif)

I checked the dwell again this morning. It was 52 degrees. I had it set at 46 degrees before my long drive on Thursday so a 6 deg increase in dwell angle (decrease in points gap) in about 200 miles. Enough to change the timing enough it was starting to sputter again. I pulled the points and think I confirmed this is just a shitty quality of points. It's hard to tell in this pic, but it looks to me like the wear block is being ground away and there is a little glob of grease on the leading edge that looks to be infused with the same material the block is made of. Of course I don't have a fresh set of identical points to compare with to confirm that's what's happening, but it's the only thing that really makes sense. A consistent decrease in gap due to the block wearing away. I have a couple sets of Bosch points on the way.



While I had the points out and just for grins, I threw the Pertronix III back in because it occurred to me I had never tried it in combo with the Bosch blue coil. It fired right up and after redialing the timing, it idled smooth although fast. Here's a question. I couldn't read the dwell angle on the Pertronix with my old Craftsman analog dwell meter. Is that to be expected? Anyway, I got my hopes up and took it for a test drive. No joy. It started bucking like a mule driving at around 20 mph. Out on the pavement, it pulled smoothly up to 100 mph, but driving at normal highway cruising speeds, it would randomly cut out. It feels almost like the rev limiter is kicking in randomly but it doesn't do this with the 050 dizzy. In other words, same result as previous tests.

I put a little extra grease on the wear block and cam lobes and spent 40 minutes cussing the fiddle-farty adjustment getting the dwell back in spec. That should stay in good enough tune until the replacement points arrive.

Just to answer Phil's last questions - we already covered the plate to distributor screw and yes, it is tight. And yes, the spring in the top of the drive shaft is installed. That wouldn't explain the symptoms anyway because I haven't seen random changes in dwell, but rather, a steady increase in dwell until the timing is changed enough to cause the engine to start sputtering. A slipping adjustment screw or wear block being ground down would fit what I'm seeing. Burnt contact surfaces seem like they'd be more likely to increase gap and therefore decrease dwell angle but I suppose something funky could happen that would weld material in heaps on one or both contact surfaces. My contacts look nearly brand new. Just a pinpoint sized black dot in the center of each surface where the spark is jumping. Totally normal wear after 1,000 miles.

[jd74914]

Sorry, haven't read the whole thread but...

I've had this very same issue and the cam follower block you have pictured was wearing very quickly. It was annoying, but as a broke undergrad messing with points really wasn't a big deal for me (funny part was this was mid-2000s...no one had any idea what I was doing haha). About 2-3k miles in it actually broke and left me on the side of the road. Interestingly the bad parts were genuine Bosch and I just assumed I had received a defective unit with maybe bad phenolic mix or defect. Replaced with a second set (also Bosch) which had a slightly different looking block. Almost appeared to be a piece of fiberglass-reinforced phenolic vs. straight phenolic. That set of points had no issues and literally went 20k miles without any adjustment required.

[bbrock]

Sorry, haven't read the whole thread but...

I've had this very same issue and the cam follower block you have pictured was wearing very quickly. It was annoying, but as a broke undergrad messing with points really wasn't a big deal for me (funny part was this was mid-2000s...no one had any idea what I was doing haha). About 2-3k miles in it actually broke and left me on the side of the road. Interestingly the bad parts were genuine Bosch and I just assumed I had received a defective unit with maybe bad phenolic mix or defect. Replaced with a second set (also Bosch) which had a slightly different looking block. Almost appeared to be a piece of fiberglass-reinforced phenolic vs. straight phenolic. That set of points had no issues and literally went 20k miles without any adjustment required.

Thanks for this! Good to know a fresh set of points might solve the problem. Not good to know that even Bosch points can be afflicted. Hopefully I'll get a good set. If I can just get it to hold a tune for the next couple thousand miles, I'll be happy. (IMG:style_emoticons/default/beerchug.gif)

[jd74914]

Totally agree-certainly worth the try for a few thousand miles. Parts are cheap anyways.

I have a feeling your issue may be exacerbated by being a bit closer to the edge than I usually ran. Given the fact that I was doing stuff on the side of the road or in my dorm parking lot a lot, usually at night, I was never breaking out a timing light or really anything but a feeler gauge. What sounded good to my ears was probably not as fine tuned as the factory specs.

I do think your ultimate goal of going to MS with COP or CNP is far better. With a good crank position signal and accurate timing it’s amazing how crisp you can get even an old motor to run (only caveat here that MS crank position calculation is kinda slow with junky hardware filters so you don’t see ultimate benefits as compared to some FPGA-based crank positioning calculations, but it’s still 1000x times better than a distributor).

[bbrock]

Totally agree-certainly worth the try for a few thousand miles. Parts are cheap anyways.

I have a feeling your issue may be exacerbated by being a bit closer to the edge than I usually ran. Given the fact that I was doing stuff on the side of the road or in my dorm parking lot a lot, usually at night, I was never breaking out a timing light or really anything but a feeler gauge. What sounded good to my ears was probably not as fine tuned as the factory specs.

I do think your ultimate goal of going to MS with COP or CNP is far better. With a good crank position signal and accurate timing it’s amazing how crisp you can get even an old motor to run (only caveat here that MS crank position calculation is kinda slow with junky hardware filters so you don’t see ultimate benefits as compared to some FPGA-based crank positioning calculations, but it’s still 1000x times better than a distributor).

Do you have any experience running a cam position sensor with MS? Looks like Mario is working on a new version of his. I'm still learning but intrigued by the ability to run sequential spark and injection. I don't know anything about calculation speeds or if the combo of cam and crank position sensors would affect that. As Phil mentioned, something important for me is having %barametric sensing because I could easily drive through a pretty massive range of elevation in a day's drive here. If I understand correctly, this involves adding a second MAP that is open to atmosphere to get an ambient pressure reference. Not sure if I have that right though.

[jd74914]

Do you have any experience running a cam position sensor with MS? Looks like Mario is working on a new version of his. I'm still learning but intrigued by the ability to run sequential spark and injection. I don't know anything about calculation speeds or if the combo of cam and crank position sensors would affect that. As Phil mentioned, something important for me is having %barametric sensing because I could easily drive through a pretty massive range of elevation in a day's drive here. If I understand correctly, this involves adding a second MAP that is open to atmosphere to get an ambient pressure reference. Not sure if I have that right though.

No, I haven't run a cam trigger. I'm not sure there is much benefit to running sequential to be honest [particularly on a T4], unless you are really trying to push to slightly higher efficiencies. In higher speed applications (think sport bike), you gain some charge time for the coils which can be critical, not an issue here. I do have a cam trigger setup (not from Mario-it's a custom jobber using an OEM distributor base with tooth wheel/hall effect sensor) which I might try one day.

You definitely want a dedicated barometric pressure sensor for your use rather than depend on a key-on correction. If running Alpha-N (TPS vs. engine speed), the barometric correction is quite important given ideal gas law. Speed density (MAP based), I'd still run one personally, but theoretically shouldn't be necessary. Frequently people run blended Alpha-N which basically mean Alpha-N at idle/low engine speeds and speed density at higher speeds, again, an important case for a barometric pressure sensor.

Are you planning on using Mario's crank sync? I've got it and think the packaging is very slick, plus he includes a hall sensor which is perfect for the MS application. As MS has poor noise filtering, and does not allow setting engine speed dependent trigger voltages, so really 'need' a hall effect sensor rather than VR since processing the square wave is easy. Typically, I'd recommend using a VR sensor as a) the edge triggering is slightly more accurate in time domain, and b) ICs in hall effect sensors sometimes switch output polarity resulting in a speed-skipping, but neither matter much if the trigger doesn't work from the start.

[peteinjp]

I used a compufire setup on my old bmw 2002. Replaces the coil as well and never had to touch it again after it was set up.

[Arno914]

If the wear block wears fast, check the distributor cam for roughness. Had that issue a long time ago and after polishing the cam surface I had no more issues and the points last.

Would be helpful to have the cam profile to remachine the cam if necessary.

[Steve73]

I had a similar point fail (fall apart) on a long haul drive in my VW a few years back. Was only a few weeks old. Was bought from a mail order parts company that has slipped in cheap non bosh parts. I called them and they refused to admit the part was not Bosh.

I've had good luck with Auto Zone rotor, cap and points on VW. Don't know if any 914 crossover. May not be your go to source. But in a pinch in could save a road trip etc.

[IronHillRestorations]

Dwell is only for points and is obsolete with Pertronix. Is it possible the OEM distributor has excessive wear? Pertronix is a solution for that.

[bbrock]

Dwell is only for points and is obsolete with Pertronix. Is it possible the OEM distributor has excessive wear? Pertronix is a solution for that.

The only two tests I have for distributor wear are wiggling the shaft (seems tight and smooth) and measuring dwell through the full rpm range which using the procedure in Haynes (and I believe the FSM) to check for wear. Change in dwell is well under 1 deg across the rpm range so within spec. Also, I would expect bearing or shaft wear to cause erratic changes in dwell rather than the smooth progression of increasing dwell angle over time.

Thanks for the clarification on dwell and Pertronix. I guess that makes sense now that I think about it.