Don Ferrette

[Mark]

What sort of pipe length do you run on your Mac 84? Not sure if you had a 67 or 84. Measurement from centre of cylinder to pipe weld line or pipe joint line. Doesn't look like a weld but most people call it that. I've got the AB pipe for that engine not the black one.

 

[Don Ferrette]

Hi Mark-

I run the AB black pipes on my MAC 84's set at 11" engine centerline to weld on pipe. This setting should be fine for the AB parabolic also on your 84. That's measuring along the side of pipe & engine not from the top. I do run the parabolic pipes on my 21, 45 & 67 MAC motors. B)

 

[Mark]

Don,

Do the 84's run a little faster with the black pipe?

 

[Mark]

Don,

I'm currently running 12" with 50% and .014 clearance in the head.

 

[Don Ferrette]

"Do the 84's run a little faster with the black pipe?"

A little faster but a bit more "touchy" on the needle than the parabolic. Did you drill the stinger out yet??

"I'm currently running 12" with 50% and .014 clearance in the head."

Pipe length is a little long if this is a hydro, head clearance should be fine. What type of boat & what prop??

 

[Mark]

Don,

Boat is a Hummingbird Hydro 60/80, prop is a stock 1667 but have since cupped it to 5.8 and cut it down to 65mm. Have not tried it yet. The old time factor keeps holding me back. I'm having trouble getting to a 1 hour gym session in the evening after work. Yeh, I have drilled the pipe already.

 

[Don Ferrette]

Don,
Boat is a Hummingbird Hydro 60/80, prop is a stock 1667 but have since cupped it to 5.8 and cut it down to 65mm. Have not tried it yet. The old time factor keeps holding me back. I'm having trouble getting to a 1 hour gym session in the evening after work. Yeh, I have drilled the pipe already.

Sounds like you should be right there. I run 1667's on the single & twin, all at 64mm diameter with 5.5" or 5.7" on the single & 5.7"'s on the twin. B)

 

[Shnick]

O.K., heres one for you...

In my Circus Circus 1/8th scale, I have a Picco .80, I bought a Macs muffled pipe, Stock # 1389 Planning to start with a Prather Stainless 255 prop.

Stock pipe length from glow plug to pipe weld is 11.5 inches.

This year I'm going to use Byron's fuel, maybe 30-45 %

How much should i cut the pipe?

Thanks...

Shnick

 

[Don Ferrette]

O.K., heres one for you...
In my Circus Circus 1/8th scale, I have a Picco .80, I bought a Macs muffled pipe, Stock # 1389 Planning to start with a Prather Stainless 255 prop.

Stock pipe length from glow plug to pipe weld is 11.5 inches.

This year I'm going to use Byron's fuel, maybe 30-45 %

How much should i cut the pipe?

Thanks...

Shnick

I'd actually start out at 12" until you get dialed in & shorten from there. My guess is you'll wind up at around 11 3/4". I measure along side of pipe & motor following exhaust centerline going from centerline of bore (glowplug) to pipe weld. B)

 

[gil sonsino]

Hi Don

My name is Gill and I" ve been involved with saw boats for many years here in Brazil.

I've been testing my new design rigger equipped with a Mac 84 using a Mac pipe at 11 1/2 with great results.

Last weekend I tried the muffled parabolic at 11 1/2 and it was difficult to turn the 2170(diam 67 cup 7.1) then went back to the Mac and no problems.

I wonder if I set Andy's pipe at 11 3/4 or 12 will be able to go really fast.

60% nitro and h.c .014.I was thinking to enlarge the hole inside the stinger to 1/4???

Any input will be appreciated.

Gill

GO FAST & STRAIGHT

 

[Don Ferrette]

Hi Don

My name is Gill and I" ve been involved with saw boats for many years here in Brazil.

I've been testing my new design rigger equipped with a Mac 84 using a Mac pipe at 11 1/2 with great results.

Last weekend I tried the muffled parabolic at 11 1/2 and it was difficult to turn the 2170(diam 67 cup 7.1) then went back to the Mac and no problems.

I wonder if I set Andy's pipe at 11 3/4 or 12 will be able to go really fast.

60% nitro and h.c .014.I was thinking to enlarge the hole inside the stinger to 1/4???

Any input will be appreciated.

Gill

GO FAST & STRAIGHT

Gil-

Drilling out the baffle is a must. Measure the i.d. of the stinger & drill out the baffle same size. Be very careful to get all the metal chips out of the pipe (it'll take a couple minutes). My 108 mph SAW run last fall was with pipe set at 10".

 

[gil sonsino]

It 's already done and just waiting next weekend for the next trial.

If you don't mind I would like to know the prop used for the 108mph.

Thanks Gill

 

[Don Ferrette]

It 's already done and just waiting next weekend for the next trial.If you don't mind I would like to know the prop used for the 108mph.

Thanks Gill

Cut 2170 & a V967/3.

 

[gil sonsino]

Thanks

Gill