What kind of ignition system are you using?

[TR3driver]

Bit after the fact here (I was out of town for T-day) but just wanted to mention that 70herald missed a decimal point. The point gap is .015", meaning that even .001" movement is enough to affect the gap significantly. And the big problem is not so much the change in dwell (coil charge time) as in ignition timing.

I never tried to measure it, but there is just a little bit of play in my TR3A. Still, with points (or with points triggering an MSD), I can see a lot of spark scatter at idle as the shaft wobbles around. Converting to a Crane XR3000 made the idle spark rock solid.

 

[Geo Hahn]

...I can see a lot of spark scatter at idle as the shaft wobbles around. Converting to a Crane XR3000 made the idle spark rock solid.

Would this be viewed using a timing light and seeing a lot of movement in the timing mark at a steady RPM?

 

[TR3driver]

Yes, exactly. Under the timing light, at idle, the mark appeared to jump around by easily 10 degrees or more. My (cheap) light doesn't work well at higher rpm, but from what I could see, there was actually less scatter at around 2.5K then it got worse again above that.

 

[70herald]

I never tried to measure it, but there is just a little bit of play in my TR3A. Still, with points (or with points triggering an MSD), I can see a lot of spark scatter at idle as the shaft wobbles around. Converting to a Crane XR3000 made the idle spark rock solid.

I also see a bit of jumping around, but no where near 10 degrees. What I do see is random misses. Hopefully this will all go away when I put in the nice new XR700 which FedEx delivered to a friend's house yesterday, I should have it in a week or so.

 

[Paul Johnson]

Interesting, but predictable discussion. See the same stories on old bike forums as well. My TR6 came to me some 30,000 miles ago with a magnetic pick-up system. I don't know what brand, and don't especially care. If and when it ever fails, I'll revert to points probably.
On an old BMW bike I ride often and far, points were on it, and I see no reason to convert them.
While electronic systems might fail someday (do you worry about them on your 2006 car?), they will deliver much more consistent spark timing, leading to better start and idle. On the other hand, points are very simple, good for 12,000 miles or so without attention, fun to play with, and also rarely fail.
In 1972, we thought a Chevy with points was dead reliable and worried about 30 year old systems. I guess my point is that there sure is a lot of hand wringing over nothing. But you guys are easy. You should see some of the forums catering to modern BMW motorcycles. These guys fret over gasoline pumps with one hose because there could possibly be 87 octane left in the hose from the last user!

 

[Darrell_Walker]

I was doing some research on what capacitive discharge type units do, and came across this article:

https://www.grmotorsports.com/backissues/mg-dyno.php

They claim a Pertronix and MSD unit were a pretty good "bang for the buck" in increased power. Of course, we only have their word that the stock system was up to spec, but interesting none the less (even if it was an MG ).

 

[DNK]

Finally a test done that quantify's the results with each piece.Seems all they usually do is put it all on and test.

 

[vettedog72]

I only changed to Pertronix because of the shaft play (the idea that slight wobble makes no difference with the pertronix) and because I could increase the plug gap by 25%. What was the effect? I could not tell a difference. But on the other hand, I think Iam still running 12v crank and 6v run.

 

[hondo402000]

pertronix and mallary MSD and no problems for going on 3 years except for the run on after turning the Ig off but I understand I need a diode in the IG lamp circuit to stop current feeding back to the unit

 

[Tinster]

Hey Canada Guy?

What kind of ignition did you put in my car??
Help me out here?

I remember a small grey can thingy and a second
piece that was skinny and mostly shiny with
2 tiny black buttons. I remember you cussin'
when you dropped them itty bitty screws down
inside the main gizzmo.

Whatever- it works pretty good.

TR-ookie

 

[martx-5]

I've heard that the condensors on the Mallory systems can be flakey, ...

Yeah, they had a bad run of condensors awhile back. From what I understand, that's all history now.

I bought a dual point Mallory with a vacuum advance for the TR3 off e-bay. I got a good deal on it, and it's basically brand new. I'll give it a shot and see how it goes when I finally get this project done.

 

[AweMan]

Electronic ignition gives better preformance no doubt about it.
The only thing I dislike about electronic ignition is WHEN it breaks in the middle of nowhere, guess what, you`re stuck.
Points on the other hand can be reconfigured to get you to the nearest civilisation.
Point in case:
My 1973 Ford Bronco 302 Cu.In. w/breaker points flat quit me high in the moutains on a seldome used 4x4 road {more like a trail}. Upon inspecting for what might be the cause, I discovered that one of the tungsten buttons had come off of the stationary side of the breakers {why I couldn`t say other than maybe faulty manufacturing} In any case I readjusted the remaing breaker arm to as close to specs as possible and yes the engine fired up although it, as you might guess didn`t run all that well, but it was enough to get me and the vehicle off of the mountain and down to a place where I could purchase a new set of points.
My Chev Blaser with electronic ignition on the other hand quit me out in the boonies coming back from a fishing trip to Idaho. It acted just like someone reached over and turned the key off and would not restart. I waited for hours for someone kind enough to stop and ask if I needed help, then waited for another few hours for my friend to come 200 miles to tow me home. My recomendation is if you have points for your car, changing to electronic ignition is fine but were it me. I would keep the point setup in the car handy for any emergency.
Just my nickles worth
Kerry

 

[martx-5]

Funny thing about those points. It always seems that there is a way to get going again.

Back in the '70's, I had a '67 Mustang with a 289 driving along Southern State Parkway on Long Island when the engine just up and died. I coasted off to the side, and figured it had to be an ignition problem, as it happened so suddenly. I popped the distributor cap, peered down inside, and saw the fiber piece on the points arm had broken off. Well, that arm has to be insulated for the points to work. I found some electrical tape in the trunk, and wrapped it around the distributor cam that the points ride on. I reset the points the best I could. I put the cap back on, and it fired up! It didn't run too good, but it got me the couple of miles I needed to get to my friends gas station where we put in some new points...after removing the tape. /bcforum/images/%%GRAEMLIN_URL%%/driving.gif

That's a true story. /bcforum/images/%%GRAEMLIN_URL%%/cheers.gif

 

[Got_All_4]

I got to say points too. I've had my TR3A on the road since 1983 and I don't ever remember changing the points. Maybe a few adjustments. I got caught up in the upgrade talk a few years ago and in my investigations I almost went with the Pertronixs. Reason being is much easier to install, slightly worn distributor shafts don't matter, OEM look and if they fail, have a set of points in your glove box and your on the road again in 10 minutes. Crane, when your down your down.

I have close to 5k on my TR250 in 2 summers and again no problems. Like others say it's what you want to do. If you modified your car for performance for racing do a lot of home work. Do it anyways. It will pay off in the end. A lot better then a pole. Leave that to the politicians!

 

[70herald]

I was doing some research on what capacitive discharge type units do, and came across this article:

https://www.grmotorsports.com/backissues/mg-dyno.php

They claim a Pertronix and MSD unit were a pretty good "bang for the buck" in increased power. Of course, we only have their word that the stock system was up to spec, but interesting none the less (even if it was an MG ).

Very interesting.

Test: Ignition Components
Description Peak hp Change from baseline
Baseline (13 deg. at 1500, stock Lucas) 56.8 0
Add Ignitor ignition 61.1 +4.3
Add MSD 6A to Ignitor 62.7 +5.9
Add performance plug wires to above 62.7 +5.9 (no help)
Ignitor, MSD 6A at 25 deg. total advance 63.5 +6.7
Ignitor, MSD 6A at 30 deg. total advance 64.3 +7.7
Ignitor, MSD 6A at 35 deg. total advance 63.2 +6.4

Now it seems that the biggest improvement came from installing the pertronix. However, it is at least somewhat likely that some of this improvement is a result of more accurate timing (eliminating influence of a worn distributor, or mechanical tolerances) In terms of value, the biggest improvement came from finding the best advance. It would seem that for overall performance (not just at max power), properly recurving the ignition timing curve would be the best investment. They didn't specify what RPM the max HP was measured at however the difference between the pertronix and Pertronix +MSD is that the spark quality degrades at higher RPM. This would be similar to a points system (less time for the coil to charge up at high RPM) A capacitor discharge system in theory will give a higher level of power even high RPM. It would be very interesting if they had also tested a system like the Crane XR700 (single spark capacitor discharge) vs the MSD system which gives multiple sparks for each ignition cycle.

 

[BryanC]

In the GRM article, they looked at the impact of ignition timing in the test and found it to be worth about 1 hp:

"We tried 25 degrees, 30 degrees, and 35 degrees of advance and found that 30 degrees was good for about one horsepower over the other two settings. While some tuners feel timing should be advanced until the engine pings, then set back a little, more than 30 degrees hurt performance even before the engine started pinging. In fact, we got better numbers at 25 degrees total advance than 35 degrees."

So it seems that most of the gain was from the Pertronix and MSD and not from the timing.

It was also interesting that they looked at tuning of the carbs to adjust the mixture and found that it made no difference on peak power:

"This car has SU carbs, so mixture is adjustable throughout the operating range. We were surprised to find that while an overly lean or overly rich mixture made the car run poorly, power was not affected in any measurable way."

That seems a little surprising and it does not address drivability but it suggests that in their test, time spent adjusting the carbs didn't pay off in terms of peak horsepower. Does anyone here have any dyno data for a TR6 that shows how they respond to carb tuning?

Bryan

 

[Tinster]

Bryan,

Paul is pretty much the expert on carbs,ignition and
dyno testing. Once he gets his old bones out of bed he will probably help you out.

Why don't you post this question again, as a new thread?
It is worth discussing in more depth.

regards,

d

 

[TR3driver]

Just for clarity, the Crane XR700 is not a capacitive-discharge unit. The XR3000 is.

The GRM article is interesting; but I have to say it contradicts both my personal experience and several test reports I've seen in other magazines (about big American iron). I've switched back and forth between stock and MSD6 several times on several cars (including my TR3A and a 25' Dodge motorhome), and never been able to detect any difference in either acceleration or fuel economy with new plugs. The MSD gives absolutely instant starts, and will fire plugs long beyond their normal service life, but the stock system seems to light a stock spark just fine.

It's kind of like building a bonfire; the size of the fire doesn't change regardless of whether you light it with a match or a blowtorch. But the match is more likely to go out in the rain.

By contrast, the XR3000 actually seemed less peppy than points. Not a lot, but enough to notice "seat of the pants". Haven't tried to scope it, but many CD ignitions actually produce a lot less energy than Kettering types. Fast rise time and higher potential spark voltage, but shorter duration spark.

Both electronic and points can fail suddenly (once had a condensor go from "needs a tune-up" to "won't run" in about a mile), but it sure is a lot cheaper to carry a spare set of points & condensor. Just toss the old ones in the glove box when you replace them.

Again IMO, it's unfair to compare OEM electronic ignitions to aftermarket units in terms of reliability. Every MSD I've owned has failed eventually, except the one I haven't installed yet. But the Buick is pushing 180,000 miles and still has it's original module. I did replace the coil the other day, but that's because an incompetent mechanic didn't seat the coil wire properly and the arcing inside the boot eventually eroded the terminal away.

 

[70herald]

"

So it seems that most of the gain was from the Pertronix and MSD and not from the timing.

It was also interesting that they looked at tuning of the carbs to adjust the mixture and found that it made no difference on peak power:



That seems a little surprising and it does not address drivability but it suggests that in their test, time spent adjusting the carbs didn't pay off in terms of peak horsepower. Does anyone here have any dyno data for a TR6 that shows how they respond to carb tuning?

Bryan

I totally agree that the largest gain came from installing the Pertronix. I would however not be surprised if a not small percentage of that gain came as a result of more accurate / consistent spark timing than as a result of the any electrical change.
The improvement gain from adjusting the timing indicates that overall improvement (and drivability) can be gained by making sure that the ignition curve is properly set up for the engine. Since this is a very low cost item (recurve) the "bang for buck ratio" is clearly greatest by getting the dizzy properly serviced.

 

[vettedog72]

I wonder if they opened the gap of the plugs and failed to state it in the artical. The main reason I changed to Pertronix was to get enough spark to open the plug gap.