1982 710k with bosch electronic ignition?

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Jimm391730
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Re: 1982 710k with bosch electronic ignition?

Post by Jimm391730 »

now i need to make sure these electronics are not getting the full 24+ volts!
When cranking the starter, the battery voltage is lower because of the current drain. Most all older ignition systems were designed around this lower voltage (sometimes much lower than typical cranking voltage to ensure that the worst case conditions like low batteries or very cold are considered) so the use a "ballast resistor" to reduce the normal running voltage to the lower design voltage. But during starting, the full battery voltage is used (as full as it can be) to ensure a good spark for starting. I am assuming that the second click out position on the switch is full battery voltage, and one click in is the reduced running voltage. With a stock Pinz wiring, this switching is done through the starter button (reduced voltage normally but full battery voltage when the starter button is depressed).

However, whoever made this modification may have added the separate ignition switch because they used a 12V ignition system. Is there a wire that connects between the two batteries (where the + of one is connected to the - of the other; there should be no wires other than between the two batteries. If there is any more wires then they probably are using the "lower" battery for a 12V source. This is bad practice, and usually means the batteries will need replacing much more often). Let us know if there is this additional wire between the batteries.
Jim M.
712W and 710M
ryzen75
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Re: 1982 710k with bosch electronic ignition?

Post by ryzen75 »

There is a single thin gauge red wire coming from the batts. into the truck. That must be the 12v source for the ignition. That actually makes me feel better despite the new batteries maybe wearing prematurely, as ive read far to much about electronic ignitions being installed and burned out by not checking running voltage to coil. Ive read others have wired other 12 v accessories from the 2nd battery, furthest from the main positive battery terminal: as well as jumping a pinz from a 12 volt vehicle the same way...Just got home, need to rest.....a vacuum advance distributor needs engine vacuum to advance properly as engine speed rises.....it could be on of the problems affecting its good running......drill and tap the manifold for a nipple????
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Jimm391730
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Re: 1982 710k with bosch electronic ignition?

Post by Jimm391730 »

The stock Pinz engine (pistons and compression ratio, cam, etc.) was not designed to require vacuum advance; it only has advance with RPM. It may or may not run better with vacuum advance. The fitting near the vacuum brake booster line on the drivers side could be used for your dizzy vacuum as long as the section with the restrictor is removed (I think the restrictor was within the hose).

Batteries, especially those that become unbalanced due to 12V loads tapped off the pair, can be maintained by charging each battery independently with a 12V charger. If you use your truck often I'd suggest doing this every week or two at the longest; if you only use it occasionally, every month should suffice. You may find that only the lower battery will need to be charged since it is the one that gets more drain from the ignition, etc. But it is never a bad idea to keep both upper and lower batteries independently charged, and often.
Jim M.
712W and 710M
ryzen75
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Joined: Tue May 09, 2017 4:12 pm

Re: 1982 710k with bosch electronic ignition?

Post by ryzen75 »

Thanks so much. Yes, engines need advance as rpm rises, and knowing these had a centrifugal advance in the first place, no advance could be one of my main issues, as it starts and idles decent....rev it and let out the clutch and it falls on its face...
Texas710
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Re: 1982 710k with bosch electronic ignition?

Post by Texas710 »

Is there a reason to not start over and go back to stock or one of the civilian variants of the 24v ignition?

Seems easier to just start over, but who knows what the PO did that might make that difficult.

Is there a reason someone would swap out the 24v ignition for a 12v, maybe availability of parts at the time?
ryzen75
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Joined: Tue May 09, 2017 4:12 pm

Re: 1982 710k with bosch electronic ignition?

Post by ryzen75 »

someone more experienced than I , did a nice job retrofitting a rabbit (also early 80's bmw's) ignition to this pinz, so much so that I thought it may have been stock. I don't know yet if I will pull the dizzy out to see if someone turned down the o.d(outside diameter)of the shaft to fit in the hole(the clamp that holds it in place is closed to much). I do not know yet how it connects to the cam. keys or gear???? this maybe very plug and play, reliable. and far cheaper than than aftermarket solutions. As well as tune-up parts are local. Millions of vee dub and beemer people love there rides, parts on every local shelf! This truck was designed when points was all there was. The military ignition was intended to be submerged.......the benefits of this electronic ignition (gas mileage, low maintenance) far outweigh points, as long as you keep the water below your waist!!!! This dizzy wont keep out water......Thanks all
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