Way back in May 2012, the paperwork snafu that nearly ended this refit project on a very disappointing note was resolved. With the boat indisputably mine, the first thing I did was buy a set of lightly used Cummins 430hp 6CTA Diamonds with ZF LRM280A gears. The engine installation was supposed to happen in 2012, but Aric Euler/Chesapeake Marine Engineering–the mechanic who said he could do the installation–only showed up to open the engine room hatches, block up the floor a bit, and assemble his gantry. All through the fall and winter of 2012, we were dancing over the open ER hatches and around the gantry waiting for the mechanic to finish the job. Eventually, I had to get the gantry out of the way and close up the ER hatches so we could install the salon roof hatch even though the engines weren’t installed. In the end, I fired the mechanic and decided to DIY the install. Fast forward to 2015, and the gantry I built is ready to go and the blisteringly hot summer making it too hot to work up high in the boat. It’s finally time to get started on the engine installation.
Gantry leg and trolley
Rounded the edges of the I-beam
Ready for the chain hoist
It’s gantry time!
After blocking the floors under the gantry legs, I hooked up the chains and lifted the 2,000lbs engine and gear. Then I rolled it into rough position and placed single 4×4 blocks of wood under the vibration isolators to get a sense of what had to happen to mate the gear to the prop shaft.
No creaking, cracking, or groaning…we’re good to go
I have to say, the gantry worked very well. With it, it’s a one-man job moving this beast of an engine around.
My amateur welds are holding up just fine
Gap at the bottom between the couplers means the front of the engine is too high
This ZF gear comes with a 7 degree down angle. The prop shaft enters the boat at an 8 degree angle. So I anticipated that the engine would be oriented up at the front by roughly 1 degree. What my assumption completely failed to account for was that these engines hadn’t come out of a Chris Craft. Every big Chris Craft boat I’ve owned has had 22-24″ between the engine stringers, and the prop shafts and engines are centered between them. What I eventually realized with the engine mounts on these Cummins engines is that they aren’t symmetrical and they weren’t made for a boat with the prop shaft centered between the stringers. That’s gonna complicate things.
And then there’s the matter of that 5/16″ gap at the bottom of the gear and shaft couplers. The amount I’ll have to drop the front of the engine to close that gap turned out to be surprising.
Front inboard vibration isolator maxed out to the inside but still overhanging the stringer
Aft outboard vibration isolator maxed out to the inside and half-way overhanging the stringer
Inboard gear mount measures 7″ inside to outside
The same pattern repeats with the inboard gear mount, where the vibration isolator can’t go any further toward the engine, but part of it hangs off of the stringer.
Houston, we have a problem
The outboard gear mount measures 9-1/2″ inside to outside…2-1/2″ more than the other side. Ever have a problem that was right in front of you for years, but you never saw it…until one day when you really, really, really didn’t need any more problems?
Yup. It was kinda like that. Seriously deflating. Then again, with the paperwork snafu, the problem with “Mr. Good but slow,” the problems with Chesapeake Marine Engineering, the major theft in 2014 and the resulting problem with the windshield fabricator to replace stolen parts, and (finally) the exploding boat next door last month…I should be used to this stuff by now.
But whatever. Gotta keep moving forward. So I marked the mounts and started thinking about machine shops.
I have to remove some old engine mount material from the stringers
The gantry makes it easy to lift the engines and move them out of the way, which I had to do to get rid of the remaining weldment from the original engine mount boxes that were welded to the boat.
The vibration isolators need to land here, so the weldment all has to go away
A circular saw with a carbide blade makes quick work of removing aluminum welds
I’ll grind the high spots that remain later. For now, I need to get the front and outboard rear engine mounts to a machine shop for modification.
Next up in our 1969 Chris Craft Roamer 46 Refit: Cummins Engine Install — Spacers
1969chriscraftroamer46 