trainfan1 wrote:

I owned/piloted & worked on many jet boats.

I owned/piloted *one* jet boat and its been about 20 years. I *know*
about the flatbottoms, (prop type) I built them for myself and others as
well as raced them but my memory could be playing tricks on me with
regard to how pumps are set up. The idea with a Day Cruiser was to
*avoid* wrenching. I do seem to recall a spline back there and I
know that some way of allowing for slight misalignment is necessary.
What is a Poly isolation coupling? Does it have a spline like a drive
shaft?


I'm looking for the brand Boat or drive/pump - that has u-joints.

You mean you're in the market?

F.H. wrote:
trainfan1 wrote:

I owned/piloted & worked on many jet boats.

I owned/piloted *one* jet boat and its been about 20 years. I *know*
about the flatbottoms, (prop type) I built them for myself and others as
well as raced them but my memory could be playing tricks on me with
regard to how pumps are set up. The idea with a Day Cruiser was to
*avoid* wrenching. I do seem to recall a spline back there and I
know that some way of allowing for slight misalignment is necessary.

Engine mounts are on adjustable screw mounts / trunnions.

http://marineengineparts.com/shopsit...dia/8-0008.jpg
http://marineengineparts.com/shopsit...ia/4417224.jpg

Alignment is done with a feeler gauge at the output flange and the
propshaft flange. It's fun. No u-joints.


What is a Poly isolation coupling? Does it have a spline like a drive
shaft?

"Rubber Damper":

http://www.pronautica.com.br/exporta...%20003_206.gif


It goes inside the two halves of a jet-drive coupler:

http://www.legdrag.com/images/ADA%20800%20Couplers.jpg
http://www.pronautica.com.br/exporta...%20003_216.jpg

for isolation & allowing for slight misalignment . No u-joints.



I'm looking for the brand Boat or drive/pump - that has u-joints.

You mean you're in the market?

You mean there are none?

Rob

"trainfan1" wrote in message
et...
F.H. wrote:
trainfan1 wrote:

I owned/piloted & worked on many jet boats.

I owned/piloted *one* jet boat and its been about 20 years. I *know*
about the flatbottoms, (prop type) I built them for myself and others as
well as raced them but my memory could be playing tricks on me with
regard to how pumps are set up. The idea with a Day Cruiser was to
*avoid* wrenching. I do seem to recall a spline back there and I know
that some way of allowing for slight misalignment is necessary.

Engine mounts are on adjustable screw mounts / trunnions.

http://marineengineparts.com/shopsit...dia/8-0008.jpg
http://marineengineparts.com/shopsit...ia/4417224.jpg

Alignment is done with a feeler gauge at the output flange and the
propshaft flange. It's fun. No u-joints.


What is a Poly isolation coupling? Does it have a spline like a drive
shaft?

"Rubber Damper":

http://www.pronautica.com.br/exporta...%20003_206.gif

It goes inside the two halves of a jet-drive coupler:

http://www.legdrag.com/images/ADA%20800%20Couplers.jpg
http://www.pronautica.com.br/exporta...%20003_216.jpg

for isolation & allowing for slight misalignment . No u-joints.



I'm looking for the brand Boat or drive/pump - that has u-joints.

You mean you're in the market?

You mean there are none?

Rob

Mine is a Jetcraft 21' Aluminum jet boat. With a 3 stage Kodiak pump.
Original power was a Ford 351W now a 350 MPI Chevy based engine. Has a
Spicer coupler with 2 U-joints. U-joints must always be used in pairs
otherwise you get a speed change on the output shaft during rotation. All
the Aluminum jet boats use basically the same setup, except for the engine
forward design and they use a jackshaft. We also adjust the engine, so
there is very little miss alignment. The splines are so if there is any
flex the shaft can move as well as side benefit easy way to pull the shaft
if needed.

Calif Bill wrote:
"trainfan1" wrote in message
et...
F.H. wrote:
trainfan1 wrote:

I owned/piloted & worked on many jet boats.
I owned/piloted *one* jet boat and its been about 20 years. I *know*
about the flatbottoms, (prop type) I built them for myself and others as
well as raced them but my memory could be playing tricks on me with
regard to how pumps are set up. The idea with a Day Cruiser was to
*avoid* wrenching. I do seem to recall a spline back there and I know
that some way of allowing for slight misalignment is necessary.
Engine mounts are on adjustable screw mounts / trunnions.

http://marineengineparts.com/shopsit...dia/8-0008.jpg
http://marineengineparts.com/shopsit...ia/4417224.jpg

Alignment is done with a feeler gauge at the output flange and the
propshaft flange. It's fun. No u-joints.


What is a Poly isolation coupling? Does it have a spline like a drive
shaft?
"Rubber Damper":

http://www.pronautica.com.br/exporta...%20003_206.gif

It goes inside the two halves of a jet-drive coupler:

http://www.legdrag.com/images/ADA%20800%20Couplers.jpg
http://www.pronautica.com.br/exporta...%20003_216.jpg

for isolation & allowing for slight misalignment . No u-joints.


I'm looking for the brand Boat or drive/pump - that has u-joints.
You mean you're in the market?
You mean there are none?

Rob

Mine is a Jetcraft 21' Aluminum jet boat. With a 3 stage Kodiak pump.
Original power was a Ford 351W now a 350 MPI Chevy based engine. Has a
Spicer coupler with 2 U-joints. U-joints must always be used in pairs
otherwise you get a speed change on the output shaft during rotation. All
the Aluminum jet boats use basically the same setup, except for the engine
forward design and they use a jackshaft. We also adjust the engine, so
there is very little miss alignment. The splines are so if there is any
flex the shaft can move as well as side benefit easy way to pull the shaft
if needed.



I think that's what I'm looking for, & that makes sense in an aluminum
river boat. I've never seen U-joints in a Berkeley or Jacuzzi sport
type boat. The pump is essentially bolted up right to the flywheel
isolator.

How do the 351W & 350 SBC compare performance wise? The 351 must have
been about 240-260hp, the MPI Chevy is ~300? How much work was the swap?

Rob

"trainfan1" wrote in message
et...
Calif Bill wrote:
"trainfan1" wrote in message
et...
F.H. wrote:
trainfan1 wrote:

I owned/piloted & worked on many jet boats.
I owned/piloted *one* jet boat and its been about 20 years. I *know*
about the flatbottoms, (prop type) I built them for myself and others
as well as raced them but my memory could be playing tricks on me with
regard to how pumps are set up. The idea with a Day Cruiser was to
*avoid* wrenching. I do seem to recall a spline back there and I
know that some way of allowing for slight misalignment is necessary.
Engine mounts are on adjustable screw mounts / trunnions.

http://marineengineparts.com/shopsit...dia/8-0008.jpg
http://marineengineparts.com/shopsit...ia/4417224.jpg

Alignment is done with a feeler gauge at the output flange and the
propshaft flange. It's fun. No u-joints.


What is a Poly isolation coupling? Does it have a spline like a drive
shaft?
"Rubber Damper":

http://www.pronautica.com.br/exporta...%20003_206.gif

It goes inside the two halves of a jet-drive coupler:

http://www.legdrag.com/images/ADA%20800%20Couplers.jpg
http://www.pronautica.com.br/exporta...%20003_216.jpg

for isolation & allowing for slight misalignment . No u-joints.


I'm looking for the brand Boat or drive/pump - that has u-joints.
You mean you're in the market?
You mean there are none?

Rob

Mine is a Jetcraft 21' Aluminum jet boat. With a 3 stage Kodiak pump.
Original power was a Ford 351W now a 350 MPI Chevy based engine. Has a
Spicer coupler with 2 U-joints. U-joints must always be used in pairs
otherwise you get a speed change on the output shaft during rotation.
All the Aluminum jet boats use basically the same setup, except for the
engine forward design and they use a jackshaft. We also adjust the
engine, so there is very little miss alignment. The splines are so if
there is any flex the shaft can move as well as side benefit easy way to
pull the shaft if needed.

I think that's what I'm looking for, & that makes sense in an aluminum
river boat. I've never seen U-joints in a Berkeley or Jacuzzi sport type
boat. The pump is essentially bolted up right to the flywheel isolator.

How do the 351W & 350 SBC compare performance wise? The 351 must have
been about 240-260hp, the MPI Chevy is ~300? How much work was the swap?

Rob

Performance wise, the 350 is much better. Have to be careful that I do not
cavitate the pump on stratup. Going to try a couple different impellers
when I can borrow same. At $4-800 impeller, do not want to buy and try.
The Chevy is 330 hp. the swap is really easy. I went from a 1991 Kodiak
351 to a 2004 Kodiak Marine motor. Has the same electrical plug for both.
So no wiring changes. The Ford has a different motor mount location on both
sides. The Starboard side is close enough that I just drilled the motor
mount bracket for the new mount, and had to move the Port mount forward
about 3". Since it is an MPI, I drilled the tank and added another port for
the injection return line, but since then replaced the fuel tank with a new
tank that has the return plumbed in. Bell housing in the rear is the same
mount for either engine. If I had gone with a different source for the 350
MPI, may have required some extra electrical and rear engine mount work.