1969 Chris Craft Roamer 46 Refit: Engine Wiring

I got the engines installed over the winter of 2015~16, but the exhaust, electrical, cooling, and fuel systems still need to be done. During a recent hot spell, I jumped into the engine room and got busy on the wiring. The biggest challenge will be figuring out how to get all of the original Chris Craft gauges, which use American standard inputs, to work with these Cummins 6CTA engines that use metric-scaled senders. The oil and water temp gauges should be easy enough: just install the Chris Craft senders. But since I will eventually install Cummins instrument panels in the engine room, the Cummins senders need to stay in place. The Chris Craft ammeter is a bit more complicated, since it gets its inputs from a shunt that was never used on these Cummins engines. In retrospect, I probably should have had the ammeters converted to volt meters back when I had the gauges refurbished, but it’s too late now. One way or another, I’ve got to get the engine electrical done if I’m going to splash later this year.

Cummins/Chris Craft wiring schematic

Cummins/Chris Craft wiring schematic

I used TinyCAD to make the schematic. There are online schematics for Cummins 6CTA marine engines, but none of them matched what I’ve got on mine. The Cummins schematics all show 2- and 3-wire alternators, but mine is a 1-wire unit. I also removed the air heaters, since they’re prone to trouble and the lads over at boatdiesel.com recommend getting rid of them. That simplifies the engine wiring quite a bit. Next, I need to make a base for the shunt and wiring harness interface terminals.

Starboard scraps will make a good base

Starboard scraps will make a good base

Just the right size

Just the right size

Position parts, drill holes

Position parts, drill holes

Locate and drill holes for engine mounting bolts

Countersink the back-side

Disassemble and clean up the shunt

Disassemble and clean up the shunt

Somebody got sloppy with blue paint some time between 1969 and 1985, when the boat went on the hard and stayed there for decades. Fortunately, it comes off easily enough.

The shunt cleaned up pretty good

The shunt cleaned up pretty good

Shunt and terminal strip test fit

Shunt and terminal strip test fit

Sand the base edges smooth

Sand the base edges smooth

Flat edges and radiused corners

Nicely radiused corners, but I’m not keen on the sharp edges

Bosche router rounds the edges nicely

 

Starboard leaves a fuzzy edge at the end of the cut zone

Starboard leaves a fuzzy edge at the end of the cut zone

Fortunately, the fuzz comes off easily with a knife.

Harness interface panel is ready to install

Harness interface panel is ready to install

The terminal strips I’m using were on the Super Seamaster twin turbo and intercooled 534ci Ford Super Duty engines that were in the boat when we found it on Purgatory Row in a southern Maryland boatyard in late 2007. I’ll eventually need to have new cover panels made. Brand new terminal strips would be OK, but I wanted to use OE and period-correct parts whenever possible.

Next up on our 1969 Chris Craft Roamer Refit: Engine Wiring II

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One comment on “1969 Chris Craft Roamer 46 Refit: Engine Wiring

  1. Kent says:

    Very impressed with your work and knowledge– Always nice to keep things “Period Correct” as I did with my ’67– 45′ Connie.. I had those same Shunts in use– Of course when I got the Boat they where disconnected.. I also refurbished the OE Tachs. but had them work by “Wire” Not Cable drive..

    She’s come along way since you found her on “Purgatory Row”– Well Done!!
    If I lived close by– I would be more than willing to help.. I’m almost glad I don’t though– Lol..

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