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Old 05-23-2009, 12:18 PM   #4
Rob Petrie E395
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Join Date: Dec 2007
Location: Woodlawn IL
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Default Re: Autometer 6871 tach

These tachs are really made to be wired into the transbrake solonoid so when its released and the 12 volts goes away the tach starts recording beyond the 10 seconds that is already being held in memory so you can get 10 seconds before the run and the auctual run. I tried to figure out a way to put a momentary switch on the throttle linkage of my footbrake car and never found a good way to do it. I ended up putting button on the steering wheel and as soon as the other guy prestages I hit it and stageto give the tach the momentary 12 volts it need to start recording. The bad part of doing it this way is, first its one more thing to do when staging the car and second if the track doesnt have autostart and the other guy takes forever to stage or tries to burn you down it wont record the whole run due to the limit on how long it will record the run. If anybody has a good way to put a monemtary switch on the throttle linkage I would hear about it. At first I tried a NOS microswitch on the throttle body thinking when I went wide open at launch it would trigger the tach but the tach needs to see 12 volts and then starts recording when the 12 volts goes away so that did not work. I tried a couple of other ways but never came up with something I felt was safe and consistant. Again if anybody has something that works and would be willing to share there idea I would like to hear about it.
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