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post #1 of (permalink) Old 02-11-2002, 02:50 PM Thread Starter
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MSD mounted inside firewall?

Is it ok to follow the factory computer's mounting idea, and mount the msd inside the jeep, and run the wires out to the distributor thru a grommet? Is there a restriction on how close the msd unit must be to the distributor? This is for an hei on an inline six by the way.


84 CJ7, 258, HEI, M/C 2100 carb, 5 inch lift, RS9000's, 33x12.5 BFG M/T's, 4.56's and Detroit softlocker, full cage & belts, Xenon flares, Dana 44 rear, GM dual diaphragm brake booster
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post #2 of (permalink) Old 02-11-2002, 05:06 PM
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Re: MSD mounted inside firewall?

Tim, I'm out on a limb here but can you use an MSD box with an HEI setup? I don't know about your MSD but I mounted my Crane inside the cab on the firewall in the factory computer location. The most important thing I guess is keeping it as dry as possible and mount using rubber washers to reduce vibrations. I won't get near as wet as most here on this board so mounting on top of the dash or on the cage is not necesary for me. The only restriction Crane set was not to lengthen the ground wire. I had more than enough wire on the harness included with the box. My $.01 Hope it helps, Maybe someone with MSD experience can add there 2/100ths.

'85 CJ7 in pieces..
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post #3 of (permalink) Old 02-11-2002, 05:21 PM
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Re: MSD mounted inside firewall?

I don't know about somw of your questions, but two things that may have bearing:

1) I've run my 6 digital on the passenger fender for almost two years and have had no problems. I can also say that I know of at least 4 other CJ's than run this config with no problems.

2) The MSD provided distributor link (if you use their distrib) is about 3-5 feet long. This would be more than enough to do what you want.

Here's a pic. I have since cleaned up some of the extraneous wiring:

'83 CJ-7 nothing original but the tub and axle tubes
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post #4 of (permalink) Old 02-11-2002, 07:38 PM
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Re: MSD mounted inside firewall?

No limit, just make sure the large red & black wires go directly to the battery, and if you have to make them longer, get some 6 Ga. wire and silver solder to do it.

And just for the record, I put every one of the modules I can up high on the INSIDE of the fire wall, above the normal MUD and KICK line if possible.

Assuming you connected to the Magnetic Trigger inside the distributor and connected that directly to the MSD unit via the Purple and Green MSD connector wires, You will need to keep the polarity of the Purple and Green wires correct, and twist those two wires together.
Don't let them get close to high voltage wiring, like the distributor cap, coil housing, or plug wires.
Keeping them close to the block and fire wall is a good idea too.
I sometimes run a bare copper 12 Ga. wire and twist the leads around that if they have to bridge a very wide open spot or open spot close to the high voltage wires.
(Ground one or both ends of the bare copper wire. This will extend your 'Ground Plane' and keep transient EM and RF noise out of your trigger circuit.)
This little trick cuts down on the false triggers a bunch!

Good luck, and ask if you have any more questions.

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