1969 Chris Craft Roamer 46 Refit: Engines! (the wrong ones…)

Our Roamer came originally outfitted with Ford 427 gas engines–the same basic engines that powered the famous GT-40s that won Le Mans. While the mighty 427 is a great motor, with 300hp each side, even the relatively lightweight aluminum Roamer hull is a lot to push around. The original owner had the boat repowered in 1973 to Super SeaMaster marine power: 534 cubic inch Ford Super Duty engines with twin turbos and an intercooler. The Super SeaMasters developed 400hp at a relatively low 3200rpm and 657 ft/lbs of torque. Very wild stuff for the early 1970s!

The Super SeaMasters were trashed from water ingestion when we obtained her in late 2007 and, having always been a diesel boat guy, I decided to repower the Roamer to diesel. While many of these 46s came with Detroit Diesel 8V-71 power, and I like Detroits, they’re not very economical, clean or quiet. I was interested in trying something else, especially since we do most of our cruising at hull speed. My thinking at the time was, why put three tons of Detroit in to get 600 max combined hp, most of which I don’t use? After talking this over with some yacht club friends, a world-cruising sailor recommended 120 or 135hp Ford Lehman engines. According to online calculators, combined 240hp is more than enough to push the hull along at 9kts @ 6gph. That sounded pretty good, especially since Lehmans with gears could be had for relatively cheap compared to newer, higher powered engines.

So, Lehmans it was!

The 1973 Super SeaMasters were truly beautiful things. But dangerous, too.

The carburetor sits at the back of the engine, just above the marine gear on a water-cooled plenum. The turbos, which were only oil-cooled(no water cooling jackets!), drew air-fuel mix from the carb and pressurized it, pushing it through hoses and chrome tubing up to the water-to-air intercooler on top of the intake manifold, where the carb would normally go. If any hose clamp let loose on the pressure side of the system… Hold onto your britches, Ethyl, we’re goin’ to the moooon!

The original invoice for the Super SeaMasters

An online inflation calculator tells me that $6,480 in 1973 equals roughly $33,500 today…and that was the price for EACH engine.

The Super SeaMasters engines had lived a hard life

Most of the damage to them was caused by being unloved–especially the part about being drowned repeatedly–while in Purgatory Row at the southern Maryland boatyard for two decades. I tried to sell them on ebay and craigslist, but got no nibbles; not surprising, since they were long-since obsolete. So I loaded them up and took them to the scrapyard. Since I’m a big fan of neat, old mechanical things, that was a sad, sad day.

The view from the rear of a Super SeaMaster looking forward

The blue thing in the lower part of the picture is the watercooled carb plenum, which sat at the back of the engine over the marine gear. The blue thing with the two holes in it at the top is the intercooler.

The raw water-cooled intercooler

All of the SeaMaster castings were things of beauty.

By contrast, the extensive water damage from rainwater that filled the bilge to well above the oil dipstick tube was a sad sight.

Removing the spark plugs revealed that each cylinder was packed full of rusty sludge. These things were never designed for submarine service.

Honey, do the turbos sound kinda funny to you?

Again…even the best turbo hardware on the planet (circa 1973) wasn’t rated for submerged service.

On October 18, 2008, I rented a high lift and moved heavy things again

Out came the galvanized steel original tanks (diesel and zinc don’t mix).

In went the heavy stuff

The new Fischer Panda 12 Mini DP genset fit very nicely in half of the space used by the original 6.5kw Kohler gas one


Next the rebuilt Lehmans went in

And another…

The view from the Reach Lift cab.

The view from the Reach Lift cab.

And finally, after sunset we got the new fuel tank in through the salon hatch hole

And with that, we (mistakenly) put a check in the box entitled Install Engines…but more on that later. One teaser hint: never, ever trust a sailor when the topic is repowering a planing powerboat! 😉

Next up: 1969 Chris Craft Roamer Refit: The Exterior Hull.


10 comments on “1969 Chris Craft Roamer 46 Refit: Engines! (the wrong ones…)

  1. […] you go searching for 534s, you’ll find this guy who pulled (and unfortunately recycled) two from a ’69 ChrisCraft he’s redoing, this […]

  2. william shettle says:

    i have a seamaster in my blackfin and an extra one in my barn. Can you tell me what a replacement carb. would be.i have a 4-barrell holly but would like to know exactly what was put on them orginally.

  3. Dave C says:

    Those hulking monsters positively DWARF a ford 460 big block. They had bore centers of 5.25 inches! They were based on fords “super duty” truck engines, and were entirely different from the Lima series v8, which the 460 comes from. No interchangeable parts, in other words. My god, I am looking at the pics of those behemoths on the trailer and next to it, and those are simply HUGE engines! What a shame you didn’t get any takers when you listed them. I would have bought them just to restore them cosmetically and display them as historical artifacts. What an addition to a gear heads garage. Oh well, thanks for sharing the pictures and the story. Incredible!

    • 1969roamer46 says:

      Thanks for the comments, Dave C, and yes, the Super Seamasters were quite a sight…extremely high quality in the marinization.
      Let me know if you’re interested in any of the turbo parts. I’ve still got one of the watercooled intercoolers that were mounted on the intake manifold.

  4. John Casteel says:

    I’m enjoying reading your articles on bringing this beauty back to life. I live here in Savannah and was curious about the Frank Harris name. We have a famous Frank Harris that was a restraunteur from California, however the address at 215 Whitaker (now a beauty supply shop) didn’t match any of his restaurant locations. Tonight I found your previous owner. Frank B. Harris owned All Make & Reliable Typewriter Company located at 215 Whitaker St. According to archived yearbooks from Armstrong College, a local university, this company also sold office files and desk supplies. I can’t wait to see this Roamer come out from under all of that plastic.
    Best wishes,

  5. John Nevill says:

    Great article. i was searching for information on the original SeaMaster products. My father worked on their original design, testing, and manufacturing, back in the 60’s and 70’s. I rememeber going to the New York Boat Show and my dad working the show for the week or so. That letterhead and photos brings back wonderful memories.
    If my memory is correct those were Ford 460 engines and bored out to 534.
    My father passed away in 1995 but I’m sure he would help out or advise if anyone needed any help. Tthat was the kind of person he was and the kind of design engineer he was.
    Good luck with your boat project.


    • 1969roamer46 says:

      Thanks, John! Yeah, the detail work on the SeaMasters was better than anything I’ve ever seen on any marine engine. Chromed MANNs come close…that’s about it. But the castings and stainless on the SeaMasters was terrific. Your old man did a fine job on them.
      I’m no expert on old gas iron, but I believe the 534 was the predecessor of the 460 in Ford’s Super Duty gas line.

    • Dave C says:

      The old sea masters were based on the ford “super duty” engine family. An enormous, Y-block design with 5.250 bore centers. The 460 was part of fords “Lima” engine family. Much smaller, much lighter. No parts interchangeability between the two families. They were designed about a decade apart. Fascinating engines, those seamasters. I can’t imagine the torque. 534 CID and boosted? Drop the compression, up the boost to 20+ psi, install a modern engine management system, and those could easily exceed a 1000 hp each. Incredible engines.

  6. Rob says:

    Hello, do you still hav e the seamasters or any of the parts for them? I would be interested in them

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