View Full Version : 1999 CHEVY K3500 7.4L
08-12-2003, 08:01 AM
I have a 99 Chevy K3500 with a Vortec 454 (7.4L) & 5 speed std. It's in a one ton dually used regularly for heavy towing. I would like to install the ignition box on the firewall in the engine compartment, but I am concerned about EXTREME underhood temperatures. Would I be better off buying the off road version of the 6A (6470) or would the standard (6200) 6A be acceptable for this application.
Also, what are the differences between your ignition box and the Jacobs unit.
Thank you in advance for your reply.
08-12-2003, 03:52 PM
For your application, I would recommend the MSD 6A, PN 6200 along with a PN 8877 Direct Plug in Harness for Single Connector Coil. This will make the installation simple and without having to cut the factory harness. The MSD 6A has been tested under extreme applications under the hood with temperatures up to 275 degrees and still running. Make sure that it is getting air circulation and it will be fine. The Offroad is for extreme vibration and waterproof. The MSD unit will have multiple sparks for better throttle response, with 460 volts to the primary side of the coil along with 20-degree spark duration up to 13,000 RPM with 14 volts supplied to the unit. We do not bash any of the competition; we let our reputation speak for it's self.
08-14-2003, 03:36 PM
Thank you again for your reply.
The only place I have found suitable for mounting the ignition box will be in the engine compartment on the firewall (passenger's side) between the radiator overflow jug and the distributor. It will be subject to some moisture from daily driving. Will the 6200 be o.k.? I don't mind paying extra for the 6470 off road unit if it will last longer. Is it (the 6470) the same as the 6200 other than the abuse proofing? Is it also capable of withstanding extreme underhood temps?
08-14-2003, 09:25 PM
The 6470 is the same unit as far as performance; the only difference is just the waterproofing and having weather tight connectors. Mounting the unit will be just fine, a little moisture won't hurt the unit and under hood temperatures won't hurt the unit, just as long as it is not next to exhaust.
11-21-2003, 03:16 PM
I just bought MSD p/n's 6200, 8231, 8877 & 32109 for my 99 K3500 454 P/U. Hopefully I'll have time over the long turkey day weekend to install them. I noticed in the instructions for the 8877, it had a wiring schematic for also installing a p/n 8680 adjustable timing control. That made me think. I really don't want to use premium fuel all the time in my gas gussler 454, but I like the power gains of a programmer that requires premium fuel when I'm towing. Rather than constantly install and remove the programmer, could I leave the premium fuel program installed and also install a 8680 to back the timing up a few degrees when I'm not towing and burning 87 octane? Or will the factory computer just override the 8680?
Thanks again & I look forward to trying out my new ignition.
11-21-2003, 03:42 PM
No that will work fine. That is one of the functions of the 8680 is to allow you to retard as you are driving and not bother any of the computer functions at all. If you have any questions about the installation etc., let us know.
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