Time for wiring tips and tricks, got any?

Skip, I want to thank you and everyone else for the input on this thread!

What would you say about a kill switch on BOTH the Pos and Neg sides?

 

As a FYI, NHRA requires the switch on the power side.


Mutt

 

Are we talking about a single switch with TWO SEPARATE CIRCUITS? Or TWO separate switches?

TWO curcuit switches DO exist, but they are VERY expensive. (and bulky)

Skip points out that if NOTHING byp***es the Master Cut-Off Switch (MCS) then the situation I refered to WILL NOT HAPPEN if the switch is in the GROUND cable.
And he is right.

A total cut-off of the ground would not cause any problems.

Using a single curcuit switch in the positive battery cable (***uming NEG ground) will "kill" everything, unless you byp*** the switch (on the GROUND side; BAT) for things like radios that have memory presets, (which I do) or EMS's (if you have any) AND in my case, interior lights. (it helps to be able to find the master cut-off in the dark; it's under the seat!)

AND, it prevents any damage to smaller components in the event you forget to turn ON the MASTER CUT-Off before trying to start the engine. (I do suffer from CRS!! )

But the drift of the questions had me thinking as I replied, that certain devices would be by-p***ing the MCS in the GROUND cable; so the situation I described, COULD happen.

So ... if your not sure what will (or won't) by-p*** the MCS; then I would put the the switch in the POS (+) battery cable. (***uming NEG (-) ground)

There are "keyed" MCS's, but most of the ones I have found, could be picked by an 11 year old kid!

One trick I have done is to mount the MCS in a totally enclosed box, holes (with grommets to protect the cable) comming out the side. This way some smart *** can't just wind a couple of turns around the two posts with a coat hanger and "jump" the switch.

One last warning. Make SURE the engine (starter) is WELL grounded. I'm a big believer of running the ground cable DIRECTLY to the block. (usually off one of the starter bolts) Especially if the battery is in the back. (trunk) Use LARGE cable (smaller cable sets up resistance)

Then a ground strap to the body from the block.

A situation that I was asked to investigate for an insurance company turned out to be the LACK of a good ground to the engine.

New car, fresh engine. Battery grounded to body, but not a good ground from the body to the engine. (new motor and trans mounts can insulate the engine from ground)

The moment of the first "firing." Throttle given a couple of pumps, starter engaged. Engine fires; and REVS to about 6000 RPM!

It seems that the throttle cable took the load of the starter and MELTED in the WIDE OPEN position!! Engine "lunched!!"