Reverse Timing

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john robert bould

Timing, Is it possible to get a electronic unit to retard instead of advance, by messing around with the wireing? A friend as a mk3 import from the states with a Thunder computer on it.
But when strobeing it the timing retards at high rev's. By approx 20 degrees.
 
If it is an analogue control module similar to an old Boyer then it is possible to get some retard at high speed by reversing the pickup wires. Usually only 2 or 3 degrees.

I have not seen 20 degrees retard at high rpm without having it programmed into a digital box although it might be possible. I have never worked with a Thunder ignition so I don't know much about it. Jim
 
john robert bould said:
But when strobeing it the timing retards at high rev's. By approx 20 degrees.
Click to expand...

How high? Is the advance normal up to a particular RPM? Could the retard be a built-in rev limiter?
 
Buy the book by Racer Jim Schmidt which reviews his practice with analog boyer, which has one curve fits all BI - so extra sluggish to accommodate Triumphs detonation, can be made to rise faster for leaps out of turns by a resister shorting the trigger leads. If just reversing the leads it can start and run I found but beats up pilot brain sense and engine guts up with the rough misfiring timing. The only way to know if an engine can benefit by retard at some load and rpm level is by dyno and speed trails. ThunderHeart makes Harley ignition that's programmable so maybe that's what was adapted to 360 twin. it takes a rather fast burn chamber with increasing ram it in breathing or boost, with upper rpms before retard helps power rather than hurts. Lower octane to get more benefit in this ignition issue zone of course.

Here's turbo article for sense of variables.
http://www.sdsefi.com/techign.htm
 
hobot said:
Buy the book by Racer Jim Schmidt which reviews his practice with analog boyer, which has one curve fits all BI - so extra sluggish to accommodate Triumphs detonation, can be made to rise faster for leaps out of turns by a resister shorting the trigger leads. If just reversing the leads it can start and run I found but beats up pilot brain sense and engine guts up with the rough misfiring timing. The only way to know if an engine can benefit by retard at some load and rpm level is by dyno and speed trails. ThunderHeart makes Harley ignition that's programmable so maybe that's what was adapted to 360 twin. it takes a rather fast burn chamber with increasing ram it in breathing or boost, with upper rpms before retard helps power rather than hurts. Lower octane to get more benefit in this ignition issue zone of course.

Here's turbo article for sense of variables.
http://www.sdsefi.com/techign.htm
Click to expand...


Just reversing the pickup leads on an analogue Boyer makes the ignition curve into a flat line. You get a little retard as the speed increases just because of the lag in the switching transistor. It is a common practice for roadracers who don't care how the engine runs below 3500 rpm. Jim
 
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