RaT build, nearly ready

[JohnsonM50]

The boat its for..
http://i35.photobucket.com/albums/d151/mes355/8921_1120601944388_1507256635_30286.jpg
http://i35.photobucket.com/albums/d151/mes355/MovieStill003.png
Above's a shortened 31.8ci OMC with a 102 gearcase. It was limited to 3" because of the tilt pin location, the water pump & limited mostly by the lower mount. To get around this I decided to extend a plate that joins the upper & lower parts of the 'sectioned' tower to replace the lower soft mount with a hard one.
http://i35.photobucket.com/albums/d151/mes355/DSCN0512.jpg
http://i35.photobucket.com/albums/d151/mes355/DSCN0511.jpg
The gearcase is 1:1, the motor will be about 16 1/2" from clamp to prop shaft center & it will weigh about 70 lbs. Most any if not all 31.8 power heads would bolt on, up to 35hp. Its 5 1/2 " shorter at the tower, the gear case & sub foot is shorter than stock so it should fit the hydro at its transom without blocking it up saving yet more weight.
Still hindsight kicked in & Id like to shorten one even more. If I had made a new extended upper steer pin plate & extended the gear case mount plate I could've used a full length steer pin. That would set the motor back about 2" more & when it turned, the side travel of the foot would be more per less turn radious. [good or bad?]. I made an assembly kit to hold it all centered & straight for welding, a steel rod from an old longshaft that fits, A ring to hold center where the drive shaft meets the motor 2 sleeves to hold centers along the middle that can be saved for next time. This motor will put like a fish-er & go like a racer.
http://i35.photobucket.com/albums/d151/mes355/DSCN0493.jpg
A long way from my 1st RaT gearcase.:)

[Mark75H]

U R sick :)

[JohnsonM50]

[QUOTE=Mark75H;93519]U R sick :) Thanks Sam, It aint easy but is fun.;)

[bandit]

With makin a mid like the racers do from pipe, since you aren't going to shift any way?

[JohnsonM50]

[QUOTE=bandit;93537]With makin a mid like the racers do from pipe, since you aren't going to shift any way?

My thinking is to make a mid that exhausts at the bottom [not too loud], drop the C of G, weight & run the stock water pump for the motor. The low pickup gear case sends water straight to the pump internally.
Id like to go with a stack but it isnt something being made for sale that I know of. I have seen pics of one made with the 22ci type Beyer stack & a home made filler block. Ive also read the 31.8s dont do well with force fed cooling & can cook before getting on plane. I guess you could build a stick tower with a pump otherwise.

[genea01]

[QUOTE=bandit;93537]With makin a mid like the racers do from pipe, since you aren't going to shift any way?

My thinking is to make a mid that exhausts at the bottom [not too loud], drop the C of G, weight & run the stock water pump for the motor. The low pickup gear case sends water straight to the pump internally.
Id like to go with a stack but it isnt something being made for sale that I know of. I have seen pics of one made with the 22ci type Beyer stack & a home made filler block. Ive also read the 31.8s dont do well with force fed cooling & can cook before getting on plane. I guess you could build a stick tower with a pump otherwise.

the guy that made hustler stacks had a mold for the omc 31.8

[JohnsonM50]

[QUOTE=genea01;93559][QUOTE=JohnsonM50;93540]

the guy that made hustler stacks had a mold for the omc 31.8
Thanks, 31.8's are legal C-mod power heads & would probably need that to compete.:cool:

[JohnsonM50]

I got the welding done today, Bob did a great job at a great price. I carefully prepped & jigged it, locked it together with threaded rod & held center with a driveshaft. I turned the driveshaft end to be a tight fit into a socket that fit tight where the the coupler rides & locked it all together on center. The expected distortion was minimal so it should be easy to fine align. Now to get a drive shaft squared & some bushings made up for the steering pin..That & a few odd$ & end$ should finish it.:D

[JohnsonM50]

[QUOTE=JohnsonM50;93770]I got the welding done today, Bob did a great job at a great price. I carefully prepped & jigged it, locked it together with threaded rod & held center with a driveshaft. I turned the driveshaft end to be a tight fit into a socket that fit tight where the the coupler rides & locked it all together on center. The expected distortion was minimal so it should be easy to fine align. Now to get a drive shaft squared & some bushings made up for the steering pin..That & a few odd$ & end$ should finish it.:D
A couple pics..
http://i35.photobucket.com/albums/d151/mes355/DSCN0517.jpg
http://i35.photobucket.com/albums/d151/mes355/DSCN0515.jpg
One of the objectives being light, 35 hp at 70lb's? Maybe, It stands at 66.

[BRIAN HENDRICK]

U R sick :)
Yes, and he got that way hanging out with Glock :eek:

I know you know, but to avoid confusion that is not a Y102, but a Yamato horizontal split Hatchet.
Ist I thought it was a Konig 'split-case' with a nose job.

You could have used a Konig 'LINKS' with the exhaust snout incorporated , and bolted it on higher, w/o the water pump.
Most of the issues with force feed on start up can be alleviated by arranging the plumbing so that the block is full of water.
I always did this on my '497', after cooking the #1.

Attached is a pic of a B-Z similar to yours. recently refinished,
and from the same area. Also, one of a 'LINKS' adapted to a M20. Neat job, and quiet.

[JohnsonM50]

Yes, and he got that way hanging out with Glock :eek:

I know you know, but to avoid confusion that is not a Y102, but a Yamato horizontal split Hatchet.
Ist I thought it was a Konig 'split-case' with a nose job.

You could have used a Konig 'LINKS' with the exhaust snout incorporated , and bolted it on higher, w/o the water pump.
Most of the issues with force feed on start up can be alleviated by arranging the plumbing so that the block is full of water.
I always did this on my '497', after cooking the #1.

Attached is a pic of a B-Z similar to yours. recently refinished,
and from the same area. Also, one of a 'LINKS' adapted to a M20. Neat job, and quiet.

I like the idea of the Konig with exhaust but haven't come across one. Thats the h-split. Its more than start up. Ive got to run a couple 'slow zones' or shut down & paddle. Oh & yup, he's quite a rat builder/driver himself. The other one with a 102 foot done several years ago had a few bugs to work out but runs nice now.
The Bezoats looks good.

[JohnsonM50]

Ive held off working on this for a few weeks, other stuff going on. The odds & ends I mentioned turn out to be a bit of work & challenge too. The exhaust tuner, fairly important to performance was aimed at a flat bottom 1" away.From there the heat would be all over the plastic water pump. I took the straight tuner & made it curved forward [maintaining dimension] to aim it at the tower exit. This aims it more at the pump- about 3" away. To control heat & flow I made 2 deflectors to interlock protecting the pump. [the aluminum deflectors double at the pump] They also channel the exhaust in an 'S' turn to the exit.
The drive shaft is out being squared & Im working next on the clamp bracket stuff. A couple pics:
http://i35.photobucket.com/albums/d151/mes355/DSCN0559.jpg
I did this with aluminum solder. It works pretty good once your used to it & prep well. I wrapped the end with a band to reinforce the corner cuts, less likely to split from heat & vibration.
http://i35.photobucket.com/albums/d151/mes355/DSCN0553.jpg
In the tower, you can see the deflectors
http://i35.photobucket.com/albums/d151/mes355/DSCN0557.jpg
The solid low mount should be interesting. A 1/2" SS threaded rod is going thru the center to assure strength.It might not need it but not a place to skimp.
http://i35.photobucket.com/albums/d151/mes355/DSCN0515.jpg

[Mark75H]

I like the idea of the Konig with exhaust but haven't come across one.

If you can come up with something interesting to trade, I have at least one spare

[JohnsonM50]

If you can come up with something interesting to trade, I have at least one spare
Thats a much more interesting proposition than any of the 'junque' I might have for trading.. Ill work on that.

[JohnsonM50]

Finally.. some final assembly
http://i35.photobucket.com/albums/d151/mes355/DSCN0621.jpg
The tower & clamp assembly. DS out getting squared & notched then it can go the rest of the way to run time.
Alot of work in the steer pin, I had to make it fit the bushings & seat the pin in the solid bottom mount.
http://i35.photobucket.com/albums/d151/mes355/DSCN0624.jpg
Heres what I did
http://i35.photobucket.com/albums/d151/mes355/DSCN0613.jpg
Its got a 1/2" SS threaded rod thru the pin to reinforce & bolt it down into its seat. The pin goes into the outer hole, has an inner shoulder thats tapped in the middle so theres lots of contact surface to avoid movement. All thats floated in silicone in case it ever 'has' to come apart.

[JohnsonM50]

Ill get it out soon I hope, want calm water & to get a chase boat on stand by too.
http://i35.photobucket.com/albums/d151/mes355/DSCN0646.jpg
http://i35.photobucket.com/albums/d151/mes355/DSCN0669.jpg
http://i35.photobucket.com/albums/d151/mes355/DSCN0674.jpg
Ive got it 1" deep with an 11P low rake prop on. Ive test started it & had the standard defiance to just run..seemed it would rev & die, kick a little then nuthin. Thru shotgun diagnostics I stumbled across the ground wire to the power pack to be only one strand from falling off. So lucky for the free fix, it now runs fine & is actually quiet. Im thinkin get it fine tuned setup wise & re-visiting the 2 barrel project with a smaller carb

[88workcar]

I love your work keep it up.

[JohnsonM50]

I love your work keep it up.Thanks Jason, I do have more stuff in mind.. heck, Id put a pinwheel in front of the carb if I thought it would go faster LoLs;)

[BRIAN HENDRICK]

I like the idea of the Konig with exhaust but haven't come across one. .

-this is approx what it would look like with a LINKS.
-u could probably put a bolt right thru the exhaust snout,
where the large rear OEM bolt goes..
-ratios were 14:14, with some 12:15
-shafts were 15mm, but most one finds were cut to 9/16".
I could loan u an empty case if u would like to see if one fits up easy.

[Mark75H]

Most were those ratios, but there were other ratios too.

Of the 6 that I have had, none had shafts altered from the stock 15mm

[JohnsonM50]

-this is approx what it would look like with a LINKS.
-u could probably put a bolt right thru the exhaust snout,
where the large rear OEM bolt goes..
-ratios were 14:14, with some 12:15
-shafts were 15mm, but most one finds were cut to 9/16".
I could loan u an empty case if u would like to see if one fits up easy.

Thanks Brain, that's pretty cool. I test ran it with the Yamato case today, 1st time on water. set deep & tucked more than I would normally to be sure it would go & see how it handled.
It made 60 like that, no problem By the time I mess with it & props it might be surprising. Different from the 102 case, it seems to hold turns better & throws more spray. Acceleration is slightly less on top but close. Im just glad it went well, has potential & didnt break.:)