Since those boxes are generally going to go in the bay somewhere for most people (and there is no room in the cab in a vette, except behind the seats) they probably are thinking "well, 150-200 will keep it dry at least, and it's not like it's 500 a few inches from the headers..."

I also have to wonder who was on the phone that day in El Paso. You get all sorts of phone help from all companies. When I wired one wrong on an old van from memory and blew it up, the first know-it-all I got said I shouldn't have hurt it by incorrectly running coil charge voltage and signal voltage together. While you could build electronics of any type to take anything, I am unaware of anything normally looking for an 8-18V signal having no problem with 450-500V from the back end....and it did blow up.

The literature sure reflects nothing to the effect of "keep it hot - please!"

I notice that mounting place in the pics - not far from mine - is one of the cooler in the engine compartment. That's reasonably far from the headers really - on the order of 10-15" and on the outside of the compartment (plus they are cast iron.) I have a big vac "reservoir" bottle near that spot and couldn't use it. (Am I the only idiot troubled by the concept of a vacuum "reservoir"? "In this can, we store 1.5 cubic feet of concentrated.....nothing......" )

The fire wall typically gets lots of hot air on it and the nose cone gets some enormous splashes. Just never seal the box and never mount it so water or other liquids from splashes or condensation could accumulate in the upper shell (keep it positively tilted somewhat - not at all inverted.) Flat, horizontal or vertical are all fine - but not upside down. The note about the space under the box is also a good one - have a gap underneath it to allow air on that edge too.

 

I mounted mine on my '74 on the passenger side in by where the winshield wipers go when they are parked, so its on the backside of the firewall. There was a grommett there and everything, it was an easy mount, and easy to get to the RPM chip (but, like most here, I put my 7k in and left it).

Though, I did have a mysterious failure, and thanks to Cardo0, I was able to quickly and easily replace it with a 6 box he had, and its been working like a champ ever since.

 

I got LOTS of room under my dash.......now that I ripped out radio, heater, AC, and all the ductwork

Seriously, I think people mount the MSD box in the engine compartment because it's probably easier to wire and easily accessable. In my case, I won't be using an MSD anyway (sacrilige!!!!)

I have a 1962 Corvette dual point tach drive distributor and MSD is not compatible with dual points. And no, I WON'T run just one set of points

Dep

 

you will LIKE IT MISTER!!!