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Starting fuel calculation question?
https://slantsix.org/forum/viewtopic.php?t=26040		 Page 3 of 3
Author:  Sam Powell [ Wed Dec 05, 2007 7:16 pm ]
Post subject: 
Thanks for the advice. The MSD has two 12 volt connections, one directly to the battery, and one that is turned on with the key. At least that is my memory of it. The key-on probably does turn on an internal relay or electronic switching curcuit of some kind. If it did not have a switched 12 volt lead, you would not be able to shut the engine off. The cooling fans are on their own relays, but the relays get their power source from a key switched 12 volt fuse.

Right now, I know I am losing almost 1 volt through the old ignition switch. When the batt reads 13.5 volts, the switched fuse blocks read 12.5 or there abouts. That was what prompted me to want to switch the 12v switched power with a relay instead of the ignition switch in the first place.
Do you have a source for a 70 Amp relay to simply turn on the main switched fuse blocks?

I have a cold now, the garage is feezing, it is snowing outside, and I don't drive the Dart in the snow. And Christmas is coming, so socially things are going crazy. So until it warms up a bit, I have plenty of time to just plan and think about this. I really appreciate your thoughts.

Sam
Author:  SlantSixDan [ Wed Dec 05, 2007 8:06 pm ]
Post subject: 
Quote:
Right now, I know I am losing almost 1 volt through the old ignition switch. When the batt reads 13.5 volts, the switched fuse blocks read 12.5 or there abouts.
Oh wow. That's a lot of voltage drop across the switch. It ought to be on your shortlist for replacement. I think this really might well account for your starting difficulty. Line voltage drops when you're cranking the engine, because of the starter's load. The colder the engine and battery, the lower the line voltage drops. It seems possible to me during cold cranking your MSD and/or ECU just aren't getting the minimum voltage they need to work correctly.
Quote:
Do you have a source for a 70 Amp relay to simply turn on the main switched fuse blocks?
Yeah...I'll put up some P/Ns for you tomorrow.
Quote:
I have a cold now, the garage is feezing, it is snowing outside
Perfect conditions for working on a car! Or at least I didn't think much of working on cars under those kinds of conditions when I was a teenager. But none of us is permanently 18, and I agree with you 'tis the season to plan and think.
Author:  Sam Powell [ Thu Dec 06, 2007 5:21 am ]
Post subject: 
Thanks Dan, I really do appreciate your expertise here. While you are at it, a mounting block or socket of some kind would be the ticket there too. I look under the hood of new cars and am always impressed with how neat the wiring harnesses look with blocks of fuses and relays under the hood. That would be my ideal if I knew what to buy. I have looked at the Painless kits, and they are kind of hard to decode what is actually in each harness kit. All I really want or need is a fuse and relay block tht I could label and apply as I wanted to.

I guess I need to make a list of circuits I want to turn on and off with a relay, and the number of curcuits I want to fuse before I start shopping. The thing is, I think the most available fuse block sold at Advance Auto, is really cheezy looking. And I have four of those now: One switched and one unswitched on each fender. There's got to be a better way. I looked under the hood of a friend's Jeep Wrangler, and it had a fuse and relay block that looked ideal. Maybe I just need to make a trip to the junk yard. I wonder how much this would cost new from the dealer? Come to think of it, they probably do not sell it without the entire harness with connectors,etc. It is probably a fortune. Maybe there is an after market replacement or upgrade part for this application?

Sam
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