On my homemade Merc triples, adding a by pass (1 to 3 and 2 to both) greatly improved idle.
On the 90 hp Merc triples those bypass passages are HUGE.
Jeff
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On my homemade Merc triples, adding a by pass (1 to 3 and 2 to both) greatly improved idle.
On the 90 hp Merc triples those bypass passages are HUGE.
Jeff
You guys got to be kidding! Lots of guys built these things and ran them for years--me, for example.
What's a Dirty Thirty and how do you build one? Take a 44 cube power head, put a Mark 30...
I too run CDI's similar ignition system on an old Mark 78. That tiny spark coil of theirs bothered me, so I ran it with the much larger Merc coil (and it worked fine. Have yet to sea trail that...
..and not the kind you drink!
Every time I yank the power head off my older Merc triple I see a whitish, ugly looking layer of...stuff. I'm wondering if this is common (and okay) since this motor...
As I recall, the bozo who did the block set clearance around .005 inched.
These are forged slugs.
Your procedure sounds like it does the same thing, but not hogging the ramp, which may not be...
Wow! Thanks for your advice--which sure is different from theirs (as different can get!)I'd better make up lots of gas!
For the 3/4 throttle and full throttle runs I might have change props...
Bored my Merc triple block .040 over and installed all new Wiseco pistons and rings. Since it was a "bit expensive", I looked up Wiseco's break in procedure and intended to follow it to the letter....
Then...why is the exhaust on the right side? Is the photo reversed?
"Inquiring minds want to know!"
Jeff
What is that? Exhaust on the right hand side?
Jeff
Thanks!
Happy Thanksgiving to all!
Jeff
Thanks. I guess a little loose is best for racing.
Jeff
I'm having an early Merc triple bored out .030 over and need to tell my boring dude what clearance I want.
Looked in my genuine Merc manual and couldn't find it. Anyone have a spec?
Thanks,
...
Found a local guy in Lothian, MD who sounds like he knows what he's doing.
Thanks all!
Jeff
Thanks. I'll keep him on the list. I'll ship a piston to whomever does the work so he/ she can fit it.
Thanks!
Jeff
Anyone near the Chesapeake Bay/ Easton/ Baltimore area know of a good closed end block boring outfit? I need to get an old Merc triple bored out.
Thanks,
Jeff
I don't blame you!
I've seen two photos of boats that launched OVER the roof of their towing vehicles!
Jeff
Gotcha. Thanks.
Jeff
If I can ask a really stupid question... How do you folks out there, with a similar looking boat as this one, keep if from shifting forward on your trailer? I note that, in this case, there's...
Horses and horsepower! A match made in ... Idaho.
Good luck, pardner!
Jeff
At least you tried something new, so you and others know it wouldn't work.
Kudoos for doing that, and nice welding work by the way.
Jeff
40 mph is not slow! Good work. If my experience means anything, you'll pick up 4 to 5 mph with the cav plate at least an inch above the keel.
Jeff
Not a high speed hull--period. You might want to start looking around for something more appropriate. (Where I boat it's rough as hell, so a deep Vee is the ticket.)
Your dogs remind me of my...
..." The flat bottom will beat ya to death on the big lakes around here "
You said it! Have the same problem where I boat. After moving to MD, I intended to build a tunnel hull until I did some...
You could 'paint stick' the motor higher with a strip of wood. Long as she's bolted on good it won't be a problem.
Jeff
Just learned about that little trick (with the light) or I would have used it.
Motor is now running fine again, on its own. Still suspect the mystery problem will re-occur, but....
Jeff
..."Boy, the timing belt sure looks loose."
They usually are without the driven pulley!
...."...sticking of the throttle advance as well"
I hand my hand on the distributor body itself as the...
..."I assume not the ADI system because of the incompatibility of the top main cap and trigger system and you have a timing belt."
You obviously know your stuff! That is exactly why I could not...
I meant serious ideas.
Jeff
This SOB of a problem has got me stumped.
Background: Mark 78 converted to late model electronic ignition. Rebuilt the motor over the winter and fired it up. Motor started instantly, but it was...
Mine also has strakes, including new set, since it runs like a submarine--the bow doesn't come up at speed. (I'm working on it!)
Jeff
Damn but that sure looks like my homemade boat!
Good luck with her.
Jeff
I suspect the manufacturer deliberately restricted the rpm to improve fuel mileage--these things are gas hogs.
Jeff
Neat, but I have to ask a question: How fast can a water jet boat go? There has to be some speed restriction on the jet drive sucking in water to blow out the back, right?
Jeff
That doesn't answer my question, however.
Jeff
That was looking good for a while.
Jeff
How about running automatic tranny fluid instead of thick grease or oil? Modern manual trannies use it to reduce friction and increase gas mileage.
Jeff
Dingy Bob made me the driveshaft adapter used with the dual carb, external reeds motor on page one. He does nice work!
Jeff
I've seen snowmobile motors used, bolted vertically to a tower, but what I've always wanted to run is a rotary engine, say a Mazda two rotor. OMC messed with them years ago and they were fast.
...
Seeing that's merely an enlarged Super Hurricane, there are lots of mods you can do and they will make a difference. I modified one with external reeds and dual carbs years ago that was a runner.
...
I hope you angled it the right direction!
Nice work.
Jeff
Dumb question: Do you run the fuel system dry after a run? That can cause dripping and make a mess in the carbs.
Like I said, a dumb question!
Jeff
It also has a 10.5 inch wide pad down there (not visible in the photo).
Jeff
Don't jump them anymore--too old for the impacts--but I sure love to wake surf! Boat is very maneuverable and does that very well.
Jeff
PS: Been doing this stuff in homemade 8 to 12 footers for...
That's my thinking as well. Gonna mount it on the starboard trim tab, with an extension long enough to always get water.
Jeff
Relying on water being thrown into it by the prop has not worked for me (at least). Motor overheated very rapidly with the cav plate just under 4 inches up. Was fine at 3 inches up.
Going to put...
...."it looks like cold workable metal."
Right! I tried heat and beat cupping a cast Merc prop and....Don't want to talk about it!
Isn't prop building fun!
Jeff
Year end report: Made some serious progress this year (though the boat is still a slug--hull dynamics problems). Was able to build two homemade props that allowed running the prop shaft about 1 1/2...
Kinda hit the carb bore a bit with the old grinder, eh? Too bad, but it shouldn't bother a thing.
Jeff
Trimming the motor out with the cav plate still running in the water is a major drag inducer--it also tries to pull the stern down. If you need to trim out, try gradually raising the motor until the...
I wouldn't recommend it. Cast bronze is not malleable and it likes to crack instead of bend.
Jeff (working on my 8th homemade prop)