340 boat motor questions
#2333714
07/08/17 05:52 PM
07/08/17 05:52 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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So I just got a pretty cool old boat with a 340, all the core plugs popped out so I pulled the intake and had cracked lifter valley. It is reverse rotation but only has about 20hrs on the boat. Can I just get the block brazed up and re-assemble and run it? This would save me the cost of buying a 340 block, boring it and buying pistons. If not can I just throw a 360 in it and run that with the reverse rotation cam from the 340? I am aware the rear main knurling on the crank is different, will it leak bad enough to worry about or can I just go with it and add a little oil every few times out? What about a 69 340/416 stroker motor sitting around the shop wasting space, can I just throw that in or is the prop and everything going to be totally wrong now? I am a little suprised the 340 has 318 port sizes n the intake and heads, is that how the marine motors were made or has someone swapped stuff around?
If it's beyond fixing... What if I decide to just sell the parts, are they worth anything? Marine manifolds, prop, bellhousing...
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 340 boat motor questions
[Re: HotRodDave]
#2333780
07/08/17 08:14 PM
07/08/17 08:14 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Just put another block in it... sounds like it was froze a couple of times... just set up the block like it was stock but change the top end with the marine stuff.. I use to own a old Chis Craft that was a reverse rotation that was a PITA .. I didnt know it was a reverse rotation engine till I got it apart
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Re: 340 boat motor questions
[Re: HotRodDave]
#2333791
07/08/17 09:11 PM
07/08/17 09:11 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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perfect std bore 340s are expensive around here if it's even possible to find one, even one that will clean up at a reasonable bore is hard to find and expensive ($500-600) then boring and buying pistons.
I just pulled the heads and they are open chamber small port heads, I bet a 318 with a compresison bump will make nearly the same power and I could ue the forged reverse rotation crank. The pistons are low compression 4 valve relief 73 type. The intake looks like a 274 4bbl but says "marine" on the bottom, perhaps I should just throw in my 273 HP engine with the backwards cam and crank, I don't need it to be fast, fuel efficency would probably be more usefull to me if it would make enough power.
Funny thing, this is the only Fury I ever seen or heard of with a 340 from the factory. It's called a ski fury.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 340 boat motor questions
[Re: HotRodDave]
#2333810
07/08/17 09:33 PM
07/08/17 09:33 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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Can I just run the trans in reverse and put a normal engine in along with a normal water pimp?
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 340 boat motor questions
[Re: HotRodDave]
#2333827
07/08/17 10:01 PM
07/08/17 10:01 PM
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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
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Milwaukee WI
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Cam is different, oil pump drive, distributor, piston pin off-set, The critical part would be the exhaust manifolds. If they are cracked, put it back on craigslist.
"use it 'till it breaks, replace as needed"
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Re: 340 boat motor questions
[Re: HotRodDave]
#2333916
07/09/17 12:57 AM
07/09/17 12:57 AM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
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Circle Track
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Lincoln Nebraska
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If not can I just throw a 360 in it and run that with the reverse rotation cam from the 340? What about a 69 340/416 stroker motor sitting around the shop wasting space, I don't know boats (tho I worked a bit once on a reverse rotation 318 outboard speedboat) but I'd sure consider one of these. I wouldn't sweat the knurl potential. EDIT I wouldn't think the piston thrust would be a problem but not sure how the oil pump would fare tho I'm sure there are solutions as its obviously already been done in the boating world.
Last edited by RapidRobert; 07/09/17 01:06 AM.
live every 24 hour block of time like it's your last day on earth
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Re: 340 boat motor questions
[Re: HotRodDave]
#2334254
07/09/17 06:34 PM
07/09/17 06:34 PM
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crabman173
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crabman173
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Melling only place that has a cam if you need one stick a 318 in there with the backwards boat only stuff ---get a good looking girl in a bikini to ride with you and it won't matter how it runs
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Re: 340 boat motor questions
[Re: HotRodDave]
#2334619
07/10/17 11:49 AM
07/10/17 11:49 AM
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Joined: Jan 2004
Posts: 8,270 fredericksburg,va
cudaman1969
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Get a good 318, just change cranks and do a balance job, you'll never know the difference. Are you sure it's a 340? That would be a fifty year old engine-boat. A lot of 318s where used up into the ninety's, maybe later. Did it have its own cooling system or fresh water. If cooled from the water itself the block, risers, heads could be junk anyway from sea-fresh water. It doesn't take long to eat them up, especially if setting awhile. Been setting here thinking about the two 400 engines we replaced in pops boat, thinkng about the cams. I can't remember how they where made different but I know both dist turned in same direction. Maybe it'll come to me later, brain fade!
Last edited by cudaman1969; 07/10/17 12:12 PM.
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Re: 340 boat motor questions
[Re: Twostick]
#2334621
07/10/17 11:52 AM
07/10/17 11:52 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Thats what I was thinking.. a single screw and a reverse direction engine.. just doesnt make a lot of cents to me... as said.. put a engine in it and change the prop... yet my old Chris was a reverse rotation single screw
Last edited by MR_P_BODY; 07/10/17 11:55 AM.
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Re: 340 boat motor questions
[Re: HotRodDave]
#2334781
07/10/17 03:55 PM
07/10/17 03:55 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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Definately reverse rotation, has a sticker on front of engine, sticker on transmission, distributor has a spacer block to hold the oil pump drive down, water pump blades are reverse rotation, prop is reverse rotation...
Definately a 340, 73 block.
Don't know difference between in/board vs in/out
It sucks in lake water for cooling, looks to be almost no rust in water jackets and manifolds are not cracked and in really good condition. Prop looks almost new with just a few scratches on the edge of one blade.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 340 boat motor questions
[Re: HotRodDave]
#2334793
07/10/17 04:10 PM
07/10/17 04:10 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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A I/O= Inboard/outboard(the drive unit is on the transom.. a inboard has the whole thing on the inside of the hull with just a shaft and prop under the hull.. yours looks like a inboard set up EDIT Yours is a inboard
Last edited by MR_P_BODY; 07/10/17 04:13 PM.
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Re: 340 boat motor questions
[Re: HotRodDave]
#2334945
07/10/17 09:29 PM
07/10/17 09:29 PM
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Joined: Dec 2005
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SRT6776
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Re: 340 boat motor questions
[Re: HotRodDave]
#2335826
07/12/17 11:50 AM
07/12/17 11:50 AM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
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If the exhaust manifolds are shot, put the thing back up for sale. Even if they're not, you would be $ ahead putting the thing back up for sale. That project boat looks like one big black hole to me. I like boats and the inboard is cool but you have to know when to call it.
To answer your questions, you can't just run the drive in reverse, well not for long anyway. Depending on the drive, they have an internal oil pump that doesn't pump in reverse. Depending on the drive (paragon? velvet?) they can be reconfigured to change the input direction. If you do that, you can basically plunk in a garden variety small block and that may be cheaper than re-configuring a SB to reverse rotation.
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Re: 340 boat motor questions
[Re: DaytonaTurbo]
#2336762
07/14/17 01:27 AM
07/14/17 01:27 AM
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Joined: May 2005
Posts: 180 merrill, wisconsin
voigtspeed
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Use the stroker get the original cam reground a bit. Have fun. Or those pistons and a 360 will give you quench and some compression to play with loose the small port heads you will not need them for torque. Boats also are great for turbo air to water inter-cooled fun.......
ACCELERATION SPECIALIST
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Re: 340 boat motor questions
[Re: HotRodDave]
#2336846
07/14/17 11:26 AM
07/14/17 11:26 AM
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Joined: Nov 2004
Posts: 3,544 Syracuse,NY
CompWedgeEngines
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I think you need to determine what kind of time and money this is really worth to you. As mentioned, 318's are easiest fix. I just finished a STD rotation 360 boat engine, and I am pulling 2 more 318's this weekend. The crank must be reverse rotation, as is the cam, as you know. The knurling cant be " fixed" to run backwards. Maybe someone has a secret silver bullet fix, but not that I know of. I can tell you, parts for older Chrysler marine engines are very difficult to find at a reasonable price, and quite simply, some of them are just hard to find period. If it uses raw fresh water, thats a bit more challenging ( whatever you do, be very careful with the little cast flanges that mount the raw water pump, which is actually the water pump " cover". They break very easily, and are NOT easy or cheap to get)than engine water, although you'll have exchanges etc at that point.Again, I think it comes down to how much to spend, vs maybe just grabbing an easier to find RVS ROT 318, and go have fun. If you were closer, I could hook you up on a 318 reverse. Best of luck.
RIP Monte Smith
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