I'm new to your forum and this is my first post but what I have seen so far of your board is very impressive. I hope that my question is one that belongs in the advanced tech section...

I am in the process of finishing a modified 71 Z28 ....496 with 671 blower just completed and dyno'd between 750 and 875 HP. This car was designed and built for both show and go and I am considering puting MSD, Coil, and bulkhead connections under the dash for asthetic reasons. Can anyone give me any thoughts or concerns that should be considered with this decision?

Thanks all!

 

Depending on the box, you may hear the capacitors discharge, its kinda a buzzing sound.
The firewall feedthroughs have been known to arc over at times. Do not use sheetmetal screws to hold it in. Use screws without a pointed tip. Better still to use nylon screws and nuts found at a model airplane hobby store.

 

Ya could make a nice swing down panel that fit's under the dash and mount all your electronics out of site under the dash. Put on a hinge and zeus flush fasteners and can be swung down for service.
The nylon screws can be had at Lowes or HD in the bolt drawers under furniture bolts. Don't get anything black as some/most will be conductive.

Welcome to the board.

 

Just for clarification, what are you NOT using the sheetmetal screws on?
I've had my coil/MSD under the dash for years. I simply drilled a hole and put a rubber gromet in it, and then ran the coil wire from the coil to the dist. I've had no problems.

 

Do not use sheetmetal screws on a firewall feedthrough. A firewall feedthrough is an item sold by MSD, Mallory and others that allows the coil to be mounted inside the vehicle and passes high voltage through 2 male plug terminals to the engine compartment. Sharp sheetmetal screws can, have and will tend to cause the spark to short to the firewall instead of going on to the distributor. This can be especially true in a dusty environment.

 

Had to go look it up. I have seen these before, but forgotten what they looked like. Anyway on the surface this doesn't make any sense. The screw holes are farther from the core than the metal fire wall hole is, so why doesn't this feedthough short to the fire wall. Unless you've over tightened the screws and cracked the feedthrough, I can't see why this would be a problem. Another possible cause would be improperly sealed wire ends. But both of these problems are installation errors not design problems.

 

The firewall is flat and isn't as an attractive of a target as a sharp sheet metal screw. Hey, I'm just trying to help and not everything on this board is hardcore tech. I have had this very problem and am just trying to pass on my experience. Somebody asked for tips.