Packard Forum Index » Modification Discussion

As my '55 Pat is a daily driver and I do rather a lot of highway driving, when I started on it four years ago I installed the Pertronix, 12v, positive ground ignition module. Realising that I'd be hard pressed to find another on short notice, I bought two of them and threw one in the glovebox. It's still there.

About four months ago, after a round-trip from Orlando to Miami and back, I decided to try to improve my fuel mileage a bit and purchased a Jacobs, multi-spark ignition system and installed it, along with a 65,000v high amp output coil. Purists will probably object to this but the system can be hidden/camouflaged, if desired, and truly improves both performance and fuel usage. I looked at several MSD units and chose the Jacobs primarily because of its price compared to others. It does what I need it to do, was easily installed and works VERY well for the price.

I have wondered for the past several years why MSD systems aren't built into modern ignition systems. It would seem that, in modern applications, all they'd have to do would be to use a hotter coil and program the onboard computer/s.

Loyd, how about a few pics!

Hi, Loyd,

I talked to a GM engineer and asked exactly that question, "Why don't OEMs use the Jacobs and/or MSD technology in their ignitions?" His answer was, "Because it isn't necessary with current EFI and spark control. An older car, with the carb not calibrated correctly and a wobbly centrifugal/vacuum distributor, especially if it uses oil, might need more than one spark to light a wet fire, but when the A/F ratio is as it should be, one spark at the right time is sufficient."

thnx, jack vines

I have a Crane H1-6 multi spark unit on the shelf and was thinking of adapting it for my '47. I was thinking that I could use a 6 volt positive ground to a 12 volt negative ground unit as the power source. I have a Crane Hi-6 on my old 84 Volvo 240 with point ignition and it works very well. Any thoughts?

"I have a Crane H1-6 multi spark unit on the shelf and was thinking of adapting it for my '47. I was thinking that I could use a 6 volt positive ground to a 12 volt negative ground unit as the power source. I have a Crane Hi-6 on my old 84 Volvo 240 with point ignition and it works very well. Any thoughts?"

As long as you can get a negative 12v timing signal to the control box when the points close I see no reason why this wouldn't work. The points or ignition module are merely switches in this application. I have to admit that I am a rank amateur at this type of work. I merely disconnected the one extra wire in the Pertronix, positive ground ignition module as it was the quickest and easiest way that I could figure out to get the negative 12v signal that the Jacobs control box required from what I was working with at the time. I ain't a mechanic nor an engineer. I adjust real property insurance claims for a living. That's one of the many reasons that I appreciate this forum so much. Even with it, since I decided to stop letting other people screw this car up and start screwing it up myself, I sometimes wind up having to do stuff two or three times before I get them right. This was one of the FEW things that I've done that worked right the first time.

I'll step down the resolution on my camera and take some photos in the next few days.

JV wrote: "I talked to a GM engineer and asked exactly that question, "Why don't OEMs use the Jacobs and/or MSD technology in their ignitions?" His answer was, "Because it isn't necessary with current EFI and spark control. An older ... "

ok. so essentialy your research confirms the GM NON-computer HEI self contained distributor as the cheapest, easiest and best solution for 12v '-' ground.

What can the engineer answer about using the GM HEI self contained distributor on the + ground and 6v systems OR any hei on engines UNDER 8:1 CR???

LLoyd wrote: "Even with it, since I decided to stop letting other people screw this car up and start screwing it up myself, I sometimes wind up having to do stuff two or three times before I get them right. This was one of the FEW things that I've done that worked right the first time."

LLoyd, i don't know how long u've been wrenching on cars but u have obviously learned the the most important lesson in the automotive world that most people with 40+ years in this hobby still have no clue about.

As for doing things 2 or 3 times begore u get it right then u certainly have me beat. It often takes me 5 or 6 tries. My most recent project i started in febuary, just finished it yesterday. About more tries than i can count on all of my fingers and toes.

Quote:

That's just because you're a slow learner....

Re: Jacobs vs MSD ignition systems. Look on eBay. I bought a couple of MSD 6 units that I haven't yet installed. The price was definitely right.

Bernardi

P.S.

I'm glad to hear that Pertronix and multi spark units work together.