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Posted by David Sherman [24.32.202.83] on Sunday, December 13, 2009 at 18:04:49 :
In Reply to: Remember the days of old... posted by Jerry in Idaho [64.139.238.43] on Sunday, December 13, 2009 at 15:51:24 :
My first girlfriend's dad had a Model A that had a timing adjustment on the steering column. It was pretty neat. On flat country roads, he's use it as a "cruise control", and he could always advance or retard it as needed depending on the gas, the weather, the hills, etc, to keep it just shy of knocking. It probably did wonders for the fuel economy compared to an engine of its era without a manual timing adjustment. I suppose at some point the marketeers decided that non-adjustability would be a selling point, just like taking all the zerks off the chassis and calling it "lifetime lubrication".
You would definitely need to set it up so the hold-down clamp maintained exactly the same tightness all the time. You couldn't just loosen the bolt and expect it to stay put. I'm pretty sure the Model A had a rigid linkage, but you could probably do it with a good quality cable. I think I'd want a light spring to return it to a reasonable "center" position of the cable came loose. Still, it shouldn't be that hard. The hold-down tension could be solved by using a shouldered bolt, tightened snug and a bellville washer to provide the friction. One problem might be that control cables are meant to pull, rather than push, so you might need a spring that pulls it to "full retard" (I'd like to see that label on the dash!), and then the cable serves only to pull against the spring for advancing it. That would probably be safe enough, so long as you set the "full retard stop" at a point where the engine would still run tolerably enough to get you out of traffic and off the road if the cable came loose.
With an electronic ignition system, the control would be trivial if you could get inside the electronics. It takes almost nothing to make a short delay electronically. You'd have to set the initial timing for maximum advance, though, and then the electronics would apply a delay according to a potentiometer on the dash, to get the spark timing where you wanted it.
Another advantage might be easier starting. I don't know how applicable this is to modern engines, but on the old one-lungers and marine engines, you'd typically retard the spark until it got running smoothly, and then move it to its running position.
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