1969 Chris Craft Roamer 46 Refit: Installing Throttle Cables & Accusync Engine Synchronizer

In preparation for (hopefully) splashing the boat in October, I’ve got the fuel system and the Fischer Panda genset installation almost done. The cable-drive tachometers are hooked up. Next, I decided to tackle the throttle cables.

Installing the new cables is pretty straightforward. I went with Seastar Xtreme CCX633. But this installation is complicated by the fact that I’m installing an Accusync twin engine synchronizer.

I bought this Accusync back in 2005 and planned to use it on the 1967 Chris Craft Constellation 52 we had at the time. But that boat was old school Detroit Diesel-powered, and it didn’t have any senders that would send a signal to the Accusync. I never used it, and it sat fallow on a shelf in my garage until just recently.

NOS Accusync, ready to install

It’s new old stock, but apparently it’s so old that, in the interim, the company decided to stop making engine synchronizers for the pleasure boat market.

It’s a time capsule!!!

How about that for a testament to how technology has changed since 2005: this high tech piece of equipment came with a state-of-the-art VHS video cassette to show you how to install it!

I haven’t had a VHS player in ages… Fortunately, the installation manual does a pretty good job of explaining what needs to happen.

The cable & wire chase in the salon is the best spot for the Accusync

I used a 17′ Seastar cable for the starboard engine, which goes from the helm controls directly to the  injector pump. That makes the starboard engine the “master.” For the port side, which is the “slave,” it will be controlled by the “master” via the Accusync. I attached a 48″ Seastar cable from the helm station to the unit. You can see it hanging just below the salon counter in the pic above.

Also, for potential critics of messy wiring, keep in mind that what you see in the chase consists of the control cables and boat wiring, extension cords that bring 120v inside the boat (since my electrical system isn’t ready to be powered up yet), and a mess of alarm motion sensor, scream alarm, LED floodlight, and streaming video camera wiring that I installed after the rat bastard thieves cleaned the boat out a few years back. When the alarm wiring and extension cords go away, the chase will be shipshape and presentable.

That’s not very shipshape

I decided to use expanded PVC as a backing board for the Accusync, and I’ll position it so  there’s easy access to the wires and cables behind it, while providing clearance for the stereo on the front side.

A handy piece of expanded PVC I’ve had laying around since 2006 will do the trick

I’ve mentioned many times before that I struggle with whether or not to keep scraps of varying sizes. Thus far, I have to say that my choices to keep scraps have paid off in both convenience and financially. This nasty, epoxy stained half-sheet of PVC has been sitting in one of my sheds, completely out of the way. And when I needed it, it was ready to go and I didn’t have to pay $250 for a new sheet, which is what they’re going for these days.

That’ll do…and I’m keeping the scrap!

Rounding the edges on both sides will help avoid cuts and abrasions when fishing wires through the cable chase

Not bad

We can lose a little material here and there

So far so good

In the engine room, my Cummins 6-CTAs came with electric tachometer senders!

The tach senders on the bellhousings aren’t standard issue, they’re an added option, and these engines also came with cable-drive tachometers that I hooked up to the OEM cable-drive tachs. That’s great news for me, since (if I understand the diagrams correctly) the Cummins senders output an RPM signal that the Accusync will use to synchronize the master and slave engine RPMs.

PVC backing board is trimmed and edges are radiused

I installed a 12vdc fuse block to power the Accusync, stereo, and amplifier

“Slave” throttle control cable is attached to the Accusync

Close to a wrap

Helm station controls at idle position

That’s an idle screw stop, right? RIGHT?!?!?

I was working strictly off of intuition, since I’ve never had a Cummins-powered boat before, and on my 427 Ford-powered Commander 42 the screw that adjusted the throttle position was only for the idle. But it turns out that what I thought was the idle stop on the injection pump is actually the WOT stop. Props to Tony Athens over at Seaboard Marine for setting me straight.

That would have made an interesting start-up if I hadn’t double-checked my work!

Morse helm controls can either ‘push’ the cables or ‘pull’ them

I had them set up to ‘push,’ just like my gas-powered Commander. Turns out they’re supposed to ‘pull’ with Cummins engines.

Throttle cables installed improperly, so helm idle position = WOT

Throttle cables installed properly, so helm idle position = idle

Confirm that WOT = WOT

Idle = idle

That’s a wrap for the throttle cable installation. The Accusync isn’t wired yet, but unlike the throttle cables that’s not absolutely necessary to splash and drive the boat.

If any readers have an Accusync, I have questions about the wiring. It’s not entirely clear which terminals send juice to the Cummins senders and which terminals receive the signal. Here’s the Accusync schematic:

It looks like “7) Signal Return” is common to both magnetic pickup senders, so that must supply the juice, but the term “signal return” doesn’t intuitively sound right: having both signals ‘return’ to the same terminal would negate the point of an engine sychronizer. If any readers have any insight on this, please let me know in the comments.

Next up in our 1969 Chris Craft Roamer 46 Refit: Aft Stateroom Vents