A discussion with a visitor here today about ignition system mods for older cars. I was doing some maintenance on my cruiser 71 Galaxie which nearly failed on me recently. A few years back I fitted a Crane multispark ignition box. That coupled with a modern Street Avenger Holley has made the car start and run nearly like a modern efi car. BUT I forgot that the points [yes I am triggering it with the original style distributor] still wear out and closed up.
The visitor, a know all know nothing reckoned I do need all that electronic crap. but believe me I do.
The car originally had a 780 vacc secondary Holley and totally standard ignition and while I could get Avgas at a reasonable price went quite well though unsurprisingly was a little flat down low with the big carb.. That stopped long ago and using 98 unleaded the car was a pig when cold and barely adequate once warmed up. I fitted the modern Holley with a Performer manifold and it was a deal better, more driveable and a little better when cold. I bough a el cheapo Pro Comp HEI dissy, it started better but the advance curve was different every time I started the car and the detonation [crook dissy coupled with very bad 98] broke a piston. I do not recomend that stuff!
Engine rebuild later I fitted a base model Crane ignition, using a Bosch [ The Autolite was buggered] points version of factory Ford dissy. Since then the car has been so much better when cold, uses a bit less fuel and is more responsive at low engine speed. As I said nearly as good as a modern car. I am using 98 octane unleaded still as it does have compression. It will run on 91 but poorly. But will get me to a site selling 98.
Fuel quality though can be very noticeable. A good tank of fuel will be a pleasure, a bad tank not so. That is where computer controlled ignition masks bad fuel. Though the economy shows it . In modern cars sometimes 98 will produce far better power and economy,, Sometimes!
Sure I know it could be a LOT better. A good electronic distributor would be a big improvement but the car is a cruiser and seldom ever sees the secondaries and more than 3000 rpm. The odd occasion the motor is 'used' it still has probably never seen more than 5000. It is a 2 tonne tank with 3.00 rear end so 5000 is the best part of 100mph in second gear. Another magnetic dissy will eventually turn up at a swap!
With this as an experience I have recomended many to do similar and have fitted a couple for customers. All cruisers though one with a pretence of being sporty. 4, 6 &8cyl cars. Results have been mixed, all better but in degrees. It appears that some 60s 70 early 80s engines are less effected by unleaded than others. Though some were dogs when new in 86 when unleaded was introduced. I know people that have 'upgraded' on those cars too with improved results.
I have fitted Mallory and MSD units too, to me they all seem to work in a similar manner at least on street cruiser/ hacks. whatever is the best price. though,, please buy reputable brands, not elcheapo Chinese rip offs.
The benefits are not nearly as pronounced with good fuel, [Avgas] though are undoubtedly there. IF you can burn unleaded though it does keep the engines far cleaner than the old leaded fuel ones. I do know people racing on unleade by preference, a lot of time , money and dyno time though to get said results. E85 is another story, but again expensive but can make good power, seemingly great for turbo engines. Use valve saver compound though at all times. Or the valves will burrow up the ports and the guides go oval. Seen lots of those!
I believe the benefits can be considerable on older engines on LPG too. The plugs do come out clean, not yellow flowers!
Modern engines with individual coil packs are usually perfectly ok for every day use. Though like all electronics [inc these multispark units] do fail and cause grief. Hence my visitors comments today.
These are critical on voltage, good earths and will accentuate problems with plug leads, dissy caps etc. Be carefull they can bite, the associated modern coils have considerable voltage and amperage. Hence again my visitors comments. I have suffered this myself, put the racer on the trailer Saturday running fine, got to the track Sunday and no spark.Grrrr, I never worked out what fixed it as I chased every connection and it then ran fine!,,, On Monday! I usually carry a twin point with coil,, but when needed I left it behind.
I guess plenty of others have comments and experience with these things. This is in the nature of giving info and also learning more for myself.
Edited by Lee Nicolle, 11 November 2015 - 12:52.
