[Jay S]

Originally Posted by jhein

Thinking about either of these safety switches, either tach based or oil pressure based, when do the come into play? Basically, when the motor stops running. No tach signal means it's not running, no oil pressure means it's either not running or it will be stopping very soon. But how often in an accident does the engine stop running? Probably not if it's a rear or side impact. Maybe not even if it's a front impact, at least not immediately. And if you're running soft lines, then what is the likelihood they're going to fail in any case? So just how important are these devices?

I do not do safety switches on the mechanical and electric pusher combinations, just the full electrics. With the engine shut off an electric 7 psi pump usually won’t pump much fuel thru most mechanical pumps. The full electrics have full flow to the carb all the time.

I usually start the car as soon as the electric pusher pump is under a load after the fuel line fills up to the mechanical pump. I don’t wait for the electric to fully fill the carb, once the mechanical pump has fuel to it, the engine does not have to crank over very much to start (about 3 seconds)