Remote mounting MSD boxes
 

My motor build is going twin plug and I'm contemplating putting the boxes in the cabin of the car, thinking maybe under the passenger seat

Is there any downside of having the boxes so far from the coils?

I don’t know if there’s any downside to mounting it on the interior, but I mounted mine on the firewall. FYI, it’s better if you can pull a pos wire from the battery versus tapping somewhere in the engine compartment.

What kind of distributor are you using? When I rebuilt my engine, I twin plugged it, but only ran the stock six lead distributor cap. I was looking for a 12 lead distributor.

the distributor is a JB racing

to satiate my desire for a clean engine bay I am considering ditching the msd dual boxes and go with a Ashlock 6pin box retrofitted for twin plug

https://ashlocktech.com/order

The JB is the one I was looking at.

I did like the MSD 6AL, because it had the soft touch rev control and it was easy to hook up a shift light. This was used on my 930, which was pretty much a track car.

Absolutely senseless to mount the CDI boxes in the cabin. Apart from the fact that I never want to have any high voltage devices producing life threatening 400-500volts each under the seats you prolong the distance from the box(es) to the coil(s) and increasing the resistance and therefore reducing the power of the spark tremendously. Also not to forget the time the spark needs to travel...Also they heat up pretty much, there is no cooling wind in the cabin etc. Only disadvantages!

Thomas

Umm okay bud

I know that race cars used to have them mounted in the cabin, mostly at the rear firewall instead under tge seats or somewhere close to the driver. But this is a complete different story. No passengers, no carpets, no heating or AC, no nothing. And a fire extingusher in the cabin. Mostly halon or similar...
On a street car completely useless and dangerous as said.

Thomas

It's not dangerous and with the proper gauge wire it will not affect spark

Have a look at the MSD Ultra boxes. They take up very little space.


http://forums.pelicanparts.com/uploa...1737555286.jpg

Compared to:

http://forums.pelicanparts.com/uploa...1737555470.jpg

I have thought about those

That's a screen name I didn't expect to see on pelican, didn't feel like going by Jesus Christ

I like to think that very few know who he was.

I struggled with the interior install. I'm very happy with the Ultras. My only mistake was not getting the ones with the rev limiter.

Those of us who drank cheap wine under bridges are aware

The part of my brain that really cares about esthetics is really leaning towards the Ashlock cdi box, the weight savings it would provide is nice too

I've got the Ashlock dual CDI box in my '72 and it's awesome....it's been rock-solid reliable for the past 20,000 miles.

I've heard nothing but good things about the man and his products

No issues in passenger compartment. Just be careful with the shielded wire(s) from distributor to MSD boxes.

When I bought my race car in 2001 it had a 3.8 on a 964 case with MSD 6AL, Blaster 2 coil, and modified SC/3 liter era distributor. Worked great.

15 years later, I decided to change classes, and had a 3.6 built up on a 993 case.

This time I needed the extra performance from twin. So two MSD boxes, two blaster coils.

At first I used a modified 964 distributor.

I made a simple bracket to attach to my simple rear fire wall, to which the MSD boxes are attached.

I used connectors for the MSD boxes such that for service I'd need to disconnect and reconnect simply and logically.

I will try to post a picture or two.

The 964 distributor I used was slightly refreshed and modified to incorporate a magnetic pickup.

It failed at Sears Point, and the result was a busted crank.

I am now at 3.6 with twin MSD, twin blaster 2, and a JB racing distributor.

One thing about twin... it can be a good idea to come up with a way to know if there is a problem with one ignition circuit, since the engine may run with one working and one not working.

And serial or parallel wiring.

This topic has come up in these forums in the past.

I have a set up that addresses this.

My application was racing, but the set up I use will work for the street too.

No problem mounting the MSD boxes inside the cabin. We did it in nascar for 3 decades and likely tens of thousands of cars across many divisions. Coils too, to keep them out of the heat.

The switch to isolate on a twin plug engine is a great idea. Light aircraft use a mag switch to isolate the two mags for just that reason; to verify both ignition systems are working. We used two MSD boxes in nascar but by rule could only use one at a time (the other was a backup, and they did fail more frequently than they should have). We had a DPDT switch to go from the "A" box to the "B" box if the engine lost power.