Ignition box retard with RPM
wonder what a stock box reads as well as a straight points distributor. One wonders if the TO-3 transistor in an ECU is rated to handle the higher speed switching of the other models (blue,red, chrome,gold)?
That's got to be a part of it. And why, with maybe exception of the NASCAR boxes, related to why they didn't recommend them for lower rpm and extended use. The RPM restriction probably relates to dwell and the ballast resistor-coil combination selected for best performance in Stock and SS class racing.
Is the timing retard an intentional design element, or is it just a function of the speed of the box?
Like YR posted, its every switch takes time. It's everything. See this discussion at moparts
Mallory Unilite timing issue
and this post in particular on speedtalk.
drag race engine ignition systems - Don Terrill’s Speed-Talk
It really doesn't matter for street use because the engine is rarely anything more than 3000 rpm.
But as Tuner shows in that post, at 6000 rpm, each degree is .00002778 sec. So if the electronics delay adds up to just .00006 seconds - there's 3 degrees!
It also only really becomes an issue when people assume
assume timing that is limited at 2500 rpm is going to be the same at 5500 rpm. Limiting the advance, especially limiting it early, is a loser for racers that need to max out the engines performance. Maybe in bracket racing its no biggie, but for stock eliminator it always is. That's who first clued me in this - a coworking who had SUN machine and ran stock eliminator. He didn't know the real reason, but he found out on the track that Direct Connection knew exactly what they were doing by installing a big secondary spring in the tach drive distributor.
(
In the DC Bulletin it says is mechanical losses and my guess is that whoever wrote that at the time believed it)
Point is that if the distributor is curved for performance in the race rpms, then it doesn't matter what the box and pickup are doing. The distributor curve compensates for it; the spark plug gets fired when it does the most good and that's the end of. Hence some of those comments in the Speedtalk thread.
I don’t know much about the inner workings. Does any one have schematics?
IIRC in the MTSC series there are some cutaways and general description. Nacho in Venezuela/Spain (hopefully the latter these days) has had some cut open and replaced transistors. He discussed it on moparts and Charger forums etc.
Kit Carlson could definately figure one out if he hasn't already done so.
Timing Light Accuracy
Thanks, that what I thought. A guy would think newer design boxes would be faster due to advancement in semiconductor technology, but maybe there other factors. Can really tell without a schematic.
For the big companies we know what any advances are used for - they can be made cheaper and sold at higher price.
