1969 Chris Craft Roamer Refit: Engine Wiring II

Well, the bad news for 2016 has officially arrived with the death of my father-in-law. 90 years is a good, long run, but my wife had just returned from a six-week family visit three weeks ago when we got the news. So I got her back on a plane and am in bachelor mode once again until mid-July when I’ll fly out to participate in the final burial ceremony. Of course, it’s a very sad thing to lose a relative, and bachelor mode has both up- and down-sides for this refit project as well as for other aspects of life. My wife is terrific and has, at times, been very helpful and hands-on in this refit, but the clothes don’t get washed and folded by themselves, nor does dinner magically appear on the table every night. So when she’s away visiting family, the load she carries in keeping our household going falls to me. I have to squeeze time for cooking, laundry, etc into an already-packed schedule. The long drives to the boatyard and back give plenty of time to reflect on her father’s life and other family matters, but I find it’s harder to focus on refit problem-solving. Fortunately, sitting in the cool bilge on hot days next to two tons of cool Cummins engines while doing the wiring tends to bring me back into focus.

Cheapo hydraulic crimper does a surprisingly good job

Cheapo hydraulic crimper does a surprisingly good job on 4/0 cables

I’ve used high end manual crimpers to make battery cables before, but I have to say these cheapo hydraulic ones on ebay do a fine job, especially for $31 shipping included.

Good crimp

Good crimp

Red colored shrink tubing identifies the + cable

Red colored shrink tubing identifies the positive cable

Good glue squeeze out after I applied heat

Good glue squeeze out after I applied heat

Ditto for the - side

Ditto for the negative side

Next, I clipped and put new ends on the OE Chris Craft engine wires

Next, I clipped and put new ends on the OE Chris Craft engine wires

The OE Chris Craft +12v supply line from the engine to the breaker panels uses 8AWG wire. All the rest–ignition, starter, water temp, oil pressure, and alarms are 10~14AWG.

Alternator and Cummins water temp sender wiring loom tucks up neatly behind fresh water filter

The alternator and water temp sender wiring loom is tucked up neatly behind the coolant filter

If you look closely at the alternator, you can see a rather small, 12AWG wire that’s connected to the 12v+ output post, which is a tiny little wire for engines that have ~100a output alternators and air heaters that put a large load on the alternators at start-up.

Starter wiring disconnected from the alternator and to the aux. starter solenoid

Starter wiring disconnected from the alternator and the aux. starter solenoid

I have learned to hate all the white paint sprayed on the wire looms and wiring. What good is it to number all the wires if you’re just going to coat them with white paint??? And when you touch the painted split loom or move the wires around, it falls off in chunks…sort of. It’s very messy stuff.

New 6AWG +12v cable from the alternator

New 6AWG +12v cable from the alternator

Cheapo crimper does 6AWG as well as it does 4/0

Cheapo crimper does 6AWG as well as it does 4/0

New 6AWG cable fits back in the alternator/H2O temp loom

New 6AWG cable fits back in the alternator/H2O temp loom

Packing all the wiring back into the split loom

Packing all the wiring back into the split loom

Because Chris Craft used ammeters with shunts instead of voltmeters, I need to reroute the alternator output cable past the battery cable terminal on the starter and have it first go through the shunt before returning to the starter. That will permit my OE ammeters to work properly at the helm, and when I eventually install Cummins panels in the engine room they’ll still get alternator output voltage from the starter battery post via the OE Cummins wiring.

But running that 6AWG wire to the shunt will be a challenge. The auxilliary starter solenoid wiring loom, which is what I’ll run the new 6AWG wire through, was installed behind the starter, and I suspect it was put in place before the starter was installed. It’s very neat and tidy doing it that way, but it’s also a lot tougher threading the loom back through that tight space between the starter and engine block than it was pulling it out. To get enough slack to make it fit, I ended up having to loosen up the loom all the way to the opposite side of the engine block.

New +12v alternator cable exits cleanly from behind the starter

New +12v alternator cable exits cleanly from behind the starter

New 6AWG wire from the shunt to the starter battery terminal

Shunt wires attached--black to alternator side, white to battery side

Shunt wires temporarily attached; black to the alternator side, white to the battery side

I’ve heard that the wire length is extremely critical for ammeters to accurately read the output from the shunts. So instead of cutting the wires I just looped and wire-tied them.

Wire ties clipped and the terminal cover installed

Wire ties clipped and the terminal cover installed

That gets the basic connections done on one engine, and now I know exactly what each wire in the Cummins loom does. But while I had my nose stuffed up against the engine block trying to pull the wires behind the starter, I noticed that somebody hadn’t been very careful installing hoses and clamps in this engine’s history.

Zero clearance to the hose clamp

Zero clearance between the starter and this heat exchanger hose and clamp

To fix that, I needed to loosen the heat exchanger and relocate it 1/4″ further back. When I went to loosen the heat exchanger clamp bolts, I found a very similar problem on the other end of the same hose. Fortunately, both problems were resolved by just moving the HEX aft a bit.

Another heat exchanger hose clamp with clearance issues.

Another heat exchanger hose clamp with clearance issues

Better to find these kinds of problems and fix them now, I suppose.

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

Advertisements

2 comments on “1969 Chris Craft Roamer Refit: Engine Wiring II

  1. Chris says:

    I’m a big fan of you blog. I’ve been reading for about a year now. It doesn’t have much applicability to my project with my 1956 Chris Craft Sportman, but it’s still fun to track your progress.

    I do have a question. I know that it’s standard to ground your battery to your engine block. But I recall the importance of the isolation transformer and the need to keep stray currents under control with a metal boat. Is the current so diminimus that it doesn’t matter?

    Keep up the good work!

    • 1969roamer46 says:

      Hi Chris, and thanks for the kudos!

      My isolation transformer converts incoming AC current to on-board AC that shares no ground or common line to the shore-side generation plant. That pretty much electrically isolates the boat on the AC side. Even if another boat in the marina is leaking AC, the isolation transformer breaks the path for my boat. BUT, if stray current in the water finds bare aluminum on my hull, it will preferentially use that as a conductor since aluminum conduct far better than fresh or salt water. I don’t know of a way to stop that beyond just keeping the hull barrier coat in good condition.

      On the DC side, I do have my batteries directly grounded to the blocks. But the blocks are electrically isolated from the hull, prop shafts, and pretty much everything else. The DC negative supply to the circuit breakers will also be directly wired to the batteries, so my boat won’t be a source for DC or AC stray current.

      If you have a blog on your Sportsman, I’d love to see it.

      Cheers,
      Q

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s