Pipe Mount Options For PT SuperSport 21

[Tim Strange]

I recently got hold of a Phil Thomas SS21, and need some suggestions for the pipe mount.

What is complicating things for me is that I have a CMB RSV07 (exhaust straight out the back) and an O.S. 21VZ-M or a Nova Rossi (which use a 180* header). I want the flexibility to use either type of motor.

Further complicating matters is that I have four pipes to try...OPS 3280, AB SS21, Cooper Silent pipe and another quiet pipe (not sure of the make). All of these pipes are very different in shapes and sizes.

I am trying to find a simple solution here without gluing a bunch of blocks of wood to the hull. It may be impossible, but I want to try.

Any help would be greatly appreciated, Tim

P.S. My camera is MIA right now, but when I find it we we play "Name That Pipe"!

 

[LarryConrad]

Turbine cowl, Speedmaster mono pipe mount for the Valvola. Unless you plan to drill lots of holes to move your engine mount forward and backward you're going to have a tough swapping from a Valvola to a Nova as the length is going to be different, and the Super Sport 21 doesn't have a surplus of room in the engine compartment. Are you running a front radio box or rear?

 

[Tim Strange]

It is the turbine cowl with front radio box...so with the CMB I am thinking that I could just make an aluminum arm that mounts to the strut mount.

I have bolted the both O.S. and the CMB up to the same mounts and they will both work using the same hole locations. The CMB's carb sticks out just about as far as the header on the O.S. There is about 1/4 to 3/8 inch between the header and the radio box.

 

[LarryConrad]

It is the turbine cowl with front radio box...so with the CMB I am thinking that I could just make an aluminum arm that mounts to the strut mount.

That's what a speedmaster mono pipe mount is, with a stand off that has a rubber grommet to hold the pipe stinger.

I have bolted the both O.S. and the CMB up to the same mounts and they will both work using the same hole locations. The CMB's carb sticks out just about as far as the header on the O.S. There is about 1/4 to 3/8 inch between the header and the radio box.

Do you have enough enough clearance between the collet and the stuffing tube? The length variation I was concerned with is on the flywheel side of the engines. If you don't have a clearance issue, you should be good to go.

 

[Tim Strange]

The clearance between the collett and flywheel is a bit close with the O.S. but should be OK. The O.S. flywheel is rather large stock, however it has been milled down quite a bit allowing it to clear the bottom of the hull. I'd like to find a shorter collett and look into the possibility of a different flywheel for the O.S.

Back to the pipe mount...The Speedmaster pipe mount looks like a good unit and will work just fine for the CMB set-up. I have a metal clamp, some strip aluminum and angle aluminum from the Hardware store. I am thinking about just epoxying a piece of 1/16 aluminum angle to the floor and attaching an adjustable bracket to it and then to the metal clamp at the stinger. This part seems pretty straight forward.

The engines that require the 180 header will need the exhaust to exit at the transom. This will require an extension tube from the pipe's stinger to the transom ... I don't think that the clamp I have or the Speedmaster unit will do the trick here. The best Idea I have had is to clamp around the fat part of the pipe and then attach that clamp to a block of wood or aluminum epoxied to the floor. The big issue is the different shapes of the pipes. I just need something clean an simple that will accept all these pipes...

I suppose that I could just support the pipe extension rather than the pipe...

Before I get too far with this....I am working on the assumption that most 21 engines like the pipe from 7 1/2" to 8 1/2" measured from the plug to the fat part of the pipe...Is this correct?