Ignition system

[lorozco]

Hi all,

 

Well.............Its been about 30 years since I have started both my 510 and 620 truck, and its that time.

 

for my 73 620 truck

1. I have a Mallory distributor (without vac advance) and I would like to convert the dual point set-up to a "unilite". Does anyone know where to get that stuff?  

2. I would also like an extra set of points.

 

For my 72 510

I also bought a distributor from a 79 620 with the built-in module. Does the primary side need a ballast resistor? What is the primary current for this set-up? What is the ohm value for the coil?

 

 

Thank you all,

 

Martin

[datzenmike]

For the 620 just get another L series distributor with points. Cheap and effective. Forget Unilite or Mallory expense for no advantage or gain. Or better yet, get another matchbox like you did for the 510.

 

For the 510 you can go two ways. Keep the original coil AND ballast resistor. It works the same but no points to worry about ever again

OR

Get the EI coil from a '79 620 truck. It's matched to the '79 distributor and works without the ballast resistor. Not only do you get rid of the points but you get a much more powerful spark output.

[banzai510(hainz)]

How about pull the gas tank to make sure you don’t plug up your carbs

Unilites made a conversion for those dual points Mallorys a while back but might be more money than it’s worth to find another distributor or just a Pertronix conversion using another Datsun distributor.so I don’t get the extra set of points comment.most people just run the first points and not hook up the 2nd for the 3rd gear switch as most people don’t use them anymore

[Pacific coast Datsun]

Search " lose the points go electronic"

Years ago with help from Mike klotz i did a writeup w/ pics & part #s detailing how to swap to electronic ignition using a GM HEI module.

[Pacific coast Datsun]

Looks like some of the pics were removed by Photobucket..the remaining pics show my wagon & the matchbox distributor.

[distributorguy]

To answer the initial question, Mallory was bought out by MSD about 3 years ago.  A year later MSD was acquired by Holley.   At that point Holley retired the Mallory brand.  Any parts you find now are either defective or Chinese knock-offs of the originals, not the same quality and they weren't known for great quality to start with.  Mallory distributors were always designed to be race distributors - meaning they need to be rebuilt or at least recurved annually to continue to run well.  The OEM Hitachi distributor was always a more robust unit, and can be made to outperform any aftermarket distributor AND last years and years without any more than an occasional points adjustment.  The fact that we ran a single point OEM Hitachi distributor at the Bonneville salt flats turning nearly 10,000 rpm run after run for 3 years is testament to their durability.  

[banzai510(hainz)]

WTF???????????

[Stoffregen Motorsports]

I agree. The original distributor is always better than the aftermarket.

 

I once took the internals of a Hitachi distributor and installed them in a modified Mallory dual point housing. I wanted the race look, but the reliability of stock components. Looked cool and worked great.

[distributorguy]

The only reason the "matchbox" distributor runs better than the points distributor is the advance curve it has.  Its closer to ideal.  When you put the Matchbox timing curve into an early points distributor, the points will outperform the electronics.  Dyno proven, repeatedly.  Getting the timing right is far more important than what trigger you use, then it comes down to reliability and consistency.  Electronics next to spark plug wires inherently have misfire issues.  Ask any electrical engineer - or any electrical hobbyist for that matter.  Low voltage signals are always affected by adjacent high voltage wires, unless you can gain ample separation AND shielding.  

 

My happiest customers are the ones I talked out of electronics.  Over fifteen thousand of them.  No joke.  The other few thousand can't or don't know how to adjust points.  

[datzenmike]

13 minutes ago, distributorguy said:

  Electronics next to spark plug wires inherently have misfire issues.  Ask any electrical engineer - or any electrical hobbyist for that matter.  Low voltage signals are always affected by adjacent high voltage wires, unless you can gain ample separation AND shielding.  

 

 

 

The radio maybe or CB.

[EDM620]

Definately clean out that carb & gas tank - this is what the inside of the float bowl looked like on mine that hadn't run in many years:

[distributorguy]

On 6/16/2020 at 1:16 PM, datzenmike said:

 

The radio maybe or CB.

 And your electronic ignition.  

[Draker]

On 6/12/2020 at 6:30 AM, banzai510(hainz) said:

WTF???????????

 

Land speed racing truck build, see his build thread.

[datzenmike]

How is it going to do that? The module has grounded the coil to build up a magnetic flux and then removed the ground causing the flux to collapse and generate a high voltage spark. That spark (and resultant EMP) lasts up to 1.5 millisecond. But what is any EMP going to upset? The module is just sitting there inert, it's job done, waiting for the next turn on event to charge the coil. And it's mounted right there on the distributor without any shielding.

 

NO ONE uses points today and haven't for decades and a good reason for this. Engineering tends to go forward not back. Less to wear out, fewer parts, lower maintenance, more efficient, higher output.

[distributorguy]

There is a constant low voltage signal pulsing on and off hundreds of times per second through the module and its wiring, and the retroactive pulse of high voltage power through the plug wires can send a false signal to the "inert???" module, similar enough to what it sees from flying magnets to cause it to fire again, between "planned" pulses.  The magnetic field that builds inside the distributor builds up until the misfire occurs -  maybe after every 100-200 cylinder fires.  The coil can discharge when its not supposed to, resulting in a weak spark (undercharged coil) the next time its supposed to fire.  Call it bullshit, but what happens on the chassis dyno is real.  It results in an average of 7-10 hp loss on ANY 4 cylinder at ANY level of build.   You can see the misfires in the air/fuel mixture.  It goes away when you use points, which is why we deliberately chose to use points through 9600 rpm, successfully.  

 

I have thousands and thousands of happy customers who now understand why and how points are better than electronics inside a distributor.  Move the electronics somewhere else, (crank fired ignition), and electronics become superior to points, in most cases but not all.  I've spent thousands of my own hard earned $$$$s to learn  how to avoid misfires, and pass on this information to those who are willing to listen.  I'd make more money selling electronics, but they don't offer the best drivability, unless you're trying to use a clapped out pile of crap distributor.  In that case you can mask some of the issues with the fixed dwell of electronics, at  the expense of EMI/RFI induced misfires.  

[datzenmike]

... and yet they work just fine. This may be true of a Hot Spark or Pertronix but the EI module has a circuit that sets the make or break within one cycle, similar to the dwell on points and rejects anything else. The 'dwell' time is decreased at low speed where not needed, to keep the coil cooler and increases with RPM so coil saturation is constant. There is a current limiting device and it turns off if ignition is on but engine not running.    

 

Points on the other hand have less output, suffer from point bounce (fixed with stiffer spring which wears them out faster) They need almost constant attention to keep at peak performance and regular replacement.

[distributorguy]

Mike, you're one of those guys who just keeps spouting BS with which you have limited experience.  Provide proof for what you're saying.  Show me how a Pertronix can "shut off" outside signals in their circuitry - or any other brand.  To say that no one uses points is idiotic.  About 60% of classic cars still use points, and that number is growing as people learn and compare.  

 

No electronic ignition is "smart enough" to reject signals that appear correct.  None of them.  Dwell time is just the "dead time" when they would normally receive no signal.  It doesn't mean they can't receive a signal.  They can and they do.  Especially Pertronix and Crane/FAST.  They have virtually no shielding.  They can be overridden by a stronger outside signal.  The early version of the Matchbox is similar.  The later version has the best shielding, but has a stack of its own problems negotiating low and high speed signals due to latency issues but makes a great daily driver setup.  ALL electronics will underperform a set of properly adjusted points, so if you're looking for the best system that needs annual maintenance (not weekly or monthly but annual) points is it.  A typical set of points lasts 30k miles with about 5-6 filing and adjustment sessions to keep it working at its best.  Always set the gap to the high side of the adjustment range, let it wear to the low side of the adjustment range, and if you're smart you'll cheat each setting by 1 thou.  That gets you into a 7k mile interval between services.  

 

All I've done for the last 14 years is this.  Ignition systems.  40-70 hours a week every week.  

After about the first 10 times seeing this issue at the chassis dyno (the engine bay provides a Faraday cage that the engine dyno doesn't) you start to see a trend.  Its consistent and irrefutable.  Its easy to solve, and it happens consistently.  After seeing it 50+ times, it becomes a standard tuning scenario.  After 100+ times its old news and you start fixing it before the first pull.  How many times have you been to the dyno Mike???  What do you use to diagnose misfires?  Your ears?  A test light?  

 

[banzai510(hainz)]

Im going to throw gas on this.(Im going to learn something)

If points so good why don't they put them in new cars???

OK Im out

[datzenmike]

On 6/23/2020 at 7:13 AM, datzenmike said:

... and yet they work just fine. This may be true of a Hot Spark or Pertronix but the EI module has a circuit that sets the make or break within one cycle, similar to the dwell on points and rejects anything else. The 'dwell' time is decreased at low speed where not needed, to keep the coil cooler and increases with RPM so coil saturation is constant. There is a current limiting device and it turns off if ignition is on but engine not running.    

 

Points on the other hand have less output, suffer from point bounce (fixed with stiffer spring which wears them out faster) They need almost constant attention to keep at peak performance and regular replacement.

 

I wasn't clear. The interference you mention may be true of Hot Spark and Pertronix (I don't know) what I do know is my EI works just fine and has for the 10? years I've had it and all I've done was replace the rotor and cap once. Outside interference would be an EMP when the coil fires not something floating around in space waiting for a chance to mess with the electronics later. As for old classic cars maybe they don't have an alternative but 40% do find a way, maybe the other 60% are hard core old school purists and simply won't let go. Today's cars (for last 40 years?) no one uses points is what I meant. I think you're splitting hairs and if you make a living with points, EI distributors put you out of work. You can never convince me to go backwards. Lets agree we disagree.

[620slodat]

I'm going to put my two cents worth in here. I'm not a professional, but to me, most people want reliability, which means not having to do anything with ignition for at least 100,000 miles. But, if you are looking for top performance then you want points, even if that means maintaining the ignition at least once a year, if not more. Anyway, that is what I'm getting from Stoffregen's statement.

 

Don

[banzai510(hainz)]

which means not having to do anything with ignition for at least 100,000 miles.

 

 

That'wont be a Datsun

[Stoffregen Motorsports]

On 6/18/2020 at 12:13 PM, datzenmike said:

 

 

NO ONE uses points today and haven't for decades and a good reason for this. Engineering tends to go forward not back. Less to wear out, fewer parts, lower maintenance, more efficient, higher output.

Well, no one uses distributors either, so...

[Stoffregen Motorsports]

You all have to understand that Jeff the distributor guy is a 1%er. He's at the top of the distributor game. He knows his stuff and he's proven it time and again.

 

Arguing about points vs electronic needs to be apples to apples, not apples to donuts.

 

Argument 1 - points require more maintenance than electronic.

Argument 2 - points can make more horsepower than electronic.

Argument 3 - most people want reliability now days, hence the mass of available electronic conversions on the market.

 

Keywords here - maintenance, reliability, power. We all know what maintenance is, and some want as little as possible while others are willing to do more to be able to go to eleven. The word reliability as relates to engines should not be used in a negative way. More reliability can often lead to less horsepower (think valvetrain). Power, some want the max, some just want enough.

 

Don't argue that one is better than the other, because all things are not equal.

 

[DanielC]

I use a points distributor in Dragon, one of my 521 trucks.  But it also has this.

 

It is a capacitive discharge box that uses the point for a trigger only.  It will easily put out about a 1/2 inch thick blue spark, with the stock coil and ballast resistor.

[620slodat]

I attributed a statement to Stoffregen when it should have been distributorguy. My bad, and I apologize to both. However, I feel both are outstanding in their fields.

 

Don