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#1
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repowering
hi guys and gals i am the proud new owner of a 50s 30ft
chris craft. This is my dilemma it is powered with twin 6cyl hercules engines. one is shot the other is on its last legs. should i rebuild the hercules or should i repower? any advice or opions would be greatly appreciated. thanks peter |
#2
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repowering
Depends on a couple factors.
First, are you maintaining this old boat as a traditional Chris Craft?? Or do you just want some reliable engines to go boating with?? Second, what do you mean by 'Shot' or 'on its last leg'.. Have they been freshwater cooled all these years or is the block rusted through?? (BTW. I purchased a '59 30' Chris Craft that had twin 283 V8 Chev OEM conversions. Both engines frozen. I tore them down but found rust through in the cylinder walls.. Purchased new/used std blocks and head and rebuilt using the cranks,cams, manifolds and reverse gear, etc.) Just like new. I don't have any idea of the availability of rebuild part for the hercules engines. I suspect they are something standard, converted by Chris Craft for marine.. Maybe someone else knows the origan of the Hercules engines. I started in boats in the '50s and always heard of the Hercules engines but never owned any. Repowering will be very expensive with any new marine engine of that size, with reverse gear is going to cost $4k each. Then you still have to modify the boat engine beds for them, maybe even new shafts and props. Good luck Peter Steve s/v Good Intentions |
#3
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repowering
THis is the basic issue:
First, are you maintaining this old boat as a traditional Chris Craft?? Or do you just want some reliable engines to go boating with?? There are lots of possibilities. Right now I'm enamored of VW diesels, and a couple of the later 100 HP types would be 'nice'. Anything like this will be expensive. Take a look at: www.lancingmarine.com for some interesting ideas. I have an idea for a low-cost conversion using modern transverse-mounted car engines including their transaxles, but I have no proof of the concept. I have heard references to this being done in the 3rd world. In the 50's I had a cruise on a Prince Edward Island lobster boat that ran a Buick straight 8 with dynaflow transmission right from the junkyard, open engine, tractor-type exhaust. The fisherman said "I can get another engine for $25 any time..." He had to rev it a bit in reverse.. but.. -- Regards, Terry King ...In The Woods In Vermont The one who Dies With The Most Parts LOSES!! What do you need? |
#4
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repowering
Good evening "Bigman", and others who may be interested,
A few little tidbits, FWIW: The engines are most likely Chris*Craft model M or a variation of that such as ML, etc. The C*C model M was a marinized version of the Hercules model JXD block assembly. The JXD block dates from sometime in the 1930s, and was used in many industrial applications such as fork lifts, "tow motors" (industrial tractors), military gensets such as the ordnance type M-7, and on and on. In the marine application, at least, the JXD block had a really nasty habit of developing cracks around the exhaust seats, which can be a major downer. Internal parts for the block assys. can probably still be found with diligent searching, but they will be priced like pure GOLD! Been there, done that, back in the mid-1960s (!) when I rebuilt a couple of them for a 31 ft. C*C I had at the time. External marine accessories are problematic: they would have to be sourced from marine graveyards, etc., or rebuild the parts you have. The original water pump (the ONLY water pump, model Ms didn't have a seperate circulating pump) was a gear-type pump with bronze gears. I believe after-market rubber impeller pumps are still available for them from Sherwood. I also believe exhaust manifolds can still be obtained from Osco Motors (www.oscomotors.com). You're looking at an expensive proposition any way you go at it. If the condition of the boat warrants spending several thousand $$$ on it, I would go with a complete replacement of the power plants with small block V8s and Warner gears, and by all means with fresh water cooling if your boating will be in the briny. If you are mechanically inclined, judicious shopping for bits & pieces at marine boneyards, eBay, Boattraderonline's engine/parts section, etc. and assembling your own engines can save you a lot of money over buying new or rebuilt complete units from a dealer. Been there, done that, too, and recently. I would not spend the money attempting to rebuild the model Ms if they have been in salt water all their life. About the gears (or "trannies"): 1:1 would be acceptable, more or less, because that's what C*C was fond of using in their later boats in the 30 ft. range that were equipped with V8s. For better efficiency, 1.5:1 gears would be better, but a bit more costly. Even better would be 2:1 gears, but you probably don't have enough clearance to swing a large enough wheel (prop) to properly load the engines. In any case, you're going to have to change the wheels if you go with a small block V8 replacement for the model Ms. You can should be able to use the same shafts IF they are not scored by the packing gland and/or the strut bearing. Large problem with putting V8s in an old 30 ft. C*C: Clearance over the top of the engine. The model Ms were (are) "bass-ackwards" engines, i.e.: the flywheel is forward. Overhead clearance is not an issue with them. Many, if not all, of the small block V8s that C*C used were also flywheel-forward engines, *AND* had more-or-less low-profile intake manifolds to minimize the overall height of the engine. Unless you go with that type of setup, and instead go with a now-conventional flywheel-aft setup, you will PROBABLY have to build little toe-stubbing doghouses into your engine hatches to provide vertical clearance for the carbs. Bummer. One way to avoid that problem (which I have done) is use Chrysler 318 (series) small block engines. Chrysler used to make a VERY low-profile intake maniflod for that engine, and used two Carter side draft carbs (YF?)that hunkered down in the vee of the engine so as not to require the overhead clearance of a more conventional arrangement. Those engines were flywheel-aft units. That's a stretch, and the manifolds & carbs would be super-hard to find, but... Another consideration, if you go with newer engines, is engine controls. Particularly controls for the gears. Most C*C model Ms had rigid mechanical controls for the gears, whereas more modern engines with hydraulic gears like Warner or Paragon use push-pull cables. That means you would have to have throttle and gear control units for each engine (pricey!) and the cables themselves. But maybe you're "lucky" and have the vacuum (or was it electromagnetic) abortion C*C called "Chris-O-Matic" gear controls, in which case (IIRC) things would be a little simpler. Maybe. And of course, a modern engine will have a 12 volt electrical system, which means changing all your instruments from 6 volt units to 12 volt units or cobbling up a 12-to-6 volt regulator to run the engine instruments. Then there are the bilge pump(s), and whatever else wants 6 volts, to contend with. Light bulbs for nav lights, etc. are the cheapest things you'll have to contend with: change them to 12 volt bulbs - the wiring doesn't even need to be changed! All that being said, I would STILL go with a complete change to more modern engines of some sort if I really wanted to USE the boat rather than play nursemaid to those poor old C*C model Ms/Herc JXDs. Sorry for rambling on, just though I might pass along the benefit (?)of 40+ years of experience "messing about with boats". Lots of boats! Ed Greeley |
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