TR4/4A TR4 ignition woes

[Kirk_Fisher]

Points, condensor and coil are bad. I am thinking about switching to the electronic ignition. Thoughts? Happy with it? Any advice or recommendations?

Also, whoever intially restored my car used a manifold that does not have a vacuum connection so I can't connect the vacuum advance to the distributor. It seems to run pretty well, but a lul at times getting into the throttle and I get really poor gas mileage (10-12 around town).

 

[Darrell_Walker]

I've been happy with Pertronix units I've installed (on a Mallory distributor on my TR4A, and on my TR8). I also used a Lumenition on the stock TR4A distributor when I ran that, and was happy with it, too. Others have reported problems with the Pertronix units, though.

Whatever you do, it probably makes sense to have Jeff at Advance Distributors rebuild yours, it will come back looking and working like new. Be aware that he will recurve to what he thinks is correct for your engine, which probably will not match the factory curve.

The vacuum connection for the distributor should be on the carb, what carbs do you have installed?

 

[Kirk_Fisher]

It has stock SU H6's

 

[TR3driver]

It has stock SU H6's

Connection for the advance should be on the bottom of the front carb. There are two bosses hanging down, one of them should be tapped for a funky threaded adapter. Sorry I don't have a good photo handy, but this should give some idea


With mileage that bad, I think you've got something else going on. The advance helps, certainly, but only by 10% or so, and you're looking for almost 100%. Hard to say what is most likely, but I would probably double-check that the centrifugal advance is working first, and that the carb jets are reliably returning up against the mixture nuts. Having a jet hang can really kill gas mileage (basically you are driving with the choke on all the time).

I'm one of those that doesn't care for the Pertronix conversion. I installed one on my TR3, then took it back off. One of the aspects that I dislike is that it requires more voltage from the battery to work than points do. I had a condition where the battery voltage was sagging while cranking, to the point that the Pertronix would not fire at all but the (gear drive) starter was still going. Ultimately turned out that the battery was failing; but there has been more than once where I left the lights on or whatever and the battery would just barely crank the engine. With points it will start, with the Pertronix no dice.

Another issue is that Pertronix warns against leaving the key on with the engine not running; something I never worry about with points. Not good practice, certainly, but again I can be careless sometimes and walk away with the key on. I did it again while working on my LED brake light conversion; just forgot that the key was on as well.

 

[Darrell_Walker]

Another issue is that Pertronix warns against leaving the key on with the engine not running; something I never worry about with points.

FYI, the Ignitor II doesn't have this problem, though I don't know if they make an Ignitor II for the TR2-4 distributor.

 

[TR3driver]

FYI, the Ignitor II doesn't have this problem, though I don't know if they make an Ignitor II for the TR2-4 distributor.

Good point, Darrell. I didn't realize the Ignitor II was available for our cars, but it appears that it is, either 9LU-241S for the early DM2 distributor (with two piece points), 9LU-149 for the later DM2 distributor (one piece points) or 9LU-142A for the 25D4 distributor.

But it's not exactly a drop-in, since they say to use their 0.6 ohm coil and carbon core wires with it. I've never had very good luck using carbon core wires with the stock distributor cap, so you'll probably want the MGB cap (with the vertical push-in connections) as well. And Ignitor II is not available in positive ground, so you'll need to convert to negative (if you haven't already and don't have a 4A).

A general caution, since we're getting into application specifics. There are different Pertronix kits depending on which distributor you have. DM2 was standard equipment until 1962 or so; but has been sold as a replacement for earlier cars for a very long time. So be sure to check what you actually have, before ordering.

PS Moss has a photo of the Ignitor II box on their web site, so maybe that is what they are selling now. But since they also list a positive ground version and the Pertronix catalog says it doesn't come in positive ground, I have to wonder if that is what they really supply. I also see where the same part number is shown with an Ignitor box, over on the Healey page
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=61916

TRF appears to only offer the Ignitor, though that might change if people start asking for the Ignitor II

 

[Darrell_Walker]

But it's not exactly a drop-in, since they say to use their 0.6 ohm coil and carbon core wires with it. I've never had very good luck using carbon core wires with the stock distributor cap, so you'll probably want the MGB cap (with the vertical push-in connections) as well. And Ignitor II is not available in positive ground, so you'll need to convert to negative (if you haven't already and don't have a 4A).

I didn't see anything that said you had to use the 0.6 ohm coil, but then you don't get the advantage of potentially higher voltages. And it says not so use solid-core wires, but that suppressor or spiral-wound are OK (which I don't know if either of those work well with the stock cap or not). Or does suppressor or spiral-wound imply carbon core?

https://www.pertronix.com/prod/ig/ignitor2/

In any case, I have the Ignitor II in my TR8, and the original Lucas Opus electronic distributor isn't the pinnacle of reliability, either.

 

[TR3driver]

Ok, maybe you're right about the coil. What I saw was 'Compatible coils can be found in the coil section of this catalog', and a chart in the coil section that lists 0.6, 1.5 and 3.0 ohm coils for Ignitor (I), but only 0.6 for Ignitor II. Sure wish they would be clearer about what works and what doesn't. I couldn't even find the installation instructions for the Ignitor II, and I'm sure not going to buy one just to learn how to hook it up!

"Suppressor" normally means carbon core (not really carbon, but carbon impregnated fiberglass I believe). Stock on your TR8, but TR2-4 came with solid core. The early caps use a pointed screw to pierce the insulation and conductor; and my experience has been that the carbon burns away around the point until eventually (possibly years later), the gap gets too big for the spark to jump reliably. Since the wire still looks fine even if you take it out of the cap, it can make for some interesting troubleshooting.

Spiral wound wires are something different, but usually too big to fit into the holes in the stock TR2-4 cap. Again, the MGB cap is the easy way to go if you want to use fancy wires. Not a big deal, I think it's even cheaper than the original and readily available from the same sources; just something to think about.