Sport 40 pipe length

Bill Gibson · Jan 8, 2011

What lengths are you guys runnin? Im runnin a PT SS 40 Stealth with a stock Mac/ AB muffled pipe/X-447 prop...i think im too short at 10-1/2"...runs real good ONLY WITH A perfect NEEDLE, but just a click or two either way, and it loads up or pops a plug...Glenn, if you read this, looks like im FINALLY gonna try your prop! Joe...you out there? Gonna try to get Sport 40 goin again in NAMBA Dist 3!!!!

TimothyJones · Jan 8, 2011

If the only way it comes up on the pipe is in a turn it may be a little to short. Try 10-3/4".I think may PT sport 40 is close to that.

Tim

Bill Gibson said:
What lengths are you guys runnin? Im runnin a PT SS 40 Stealth with a stock Mac/ AB muffled pipe/X-447 prop...i think im too short at 10-1/2"...runs real good ONLY WITH A perfect NEEDLE, but just a click or two either way, and it loads up or pops a plug...Glenn, if you read this, looks like im FINALLY gonna try your prop! Joe...you out there? Gonna try to get Sport 40 goin again in NAMBA Dist 3!!!!

Ray Sametz · Jan 8, 2011

Bill Gibson said:
What lengths are you guys runnin? Im runnin a PT SS 40 Stealth with a stock Mac/ AB muffled pipe/X-447 prop...i think im too short at 10-1/2"...runs real good ONLY WITH A perfect NEEDLE, but just a click or two either way, and it loads up or pops a plug...Glenn, if you read this, looks like im FINALLY gonna try your prop! Joe...you out there? Gonna try to get Sport 40 goin again in NAMBA Dist 3!!!!

Pull the pipe to 10-3/4, put a 450 on it, and set the needle at 64 on a Boris meter. OMHO

glenng · Jan 8, 2011

Bill Gibson said:
What lengths are you guys runnin? Im runnin a PT SS 40 Stealth with a stock Mac/ AB muffled pipe/X-447 prop...i think im too short at 10-1/2"...runs real good ONLY WITH A perfect NEEDLE, but just a click or two either way, and it loads up or pops a plug...Glenn, if you read this, looks like im FINALLY gonna try your prop! Joe...you out there? Gonna try to get Sport 40 goin again in NAMBA Dist 3!!!!

Hi Bill! 10 1/2" is probably not too long for a small prop like that. The guys up here @ 4300 ft were running under 10 with the parabolic pipes and X447/3 at the last race in October but were inconsistant in the in the early (hotter) part of the season. I gave up on the parabolic pipe and bought a Macs 10 cc Aero pipe set at 10" the boat would idle without stalling. prop was a X448. Gonna try some more props next year X646/3 X648 P230 and Texas cut 230 and the X447/3. Aero pipe seems a lot less fussy .

Glenn

Duck899 · Jan 8, 2011

Ditto on the Mac 10cc aero pipe.... It may seem like something irrelevant, but that pipe just flat out pulls big props at big rpm and being short. Not finicky at all, just works. I run mine at 10 1/8" with an Octura 1455/2 pitched to 3.2" AA45 in a Mutt.

Bill Gibson · Jan 8, 2011

That was the other thing...just remembered that it would pull an X-450 on cool days and haul butt! However towards the summer it wouldnt even launch without hangin a smaller prop on it! REAL persnickity!

Bill Gibson · Jan 8, 2011

Duck899 said:
Ditto on the Mac 10cc aero pipe.... It may seem like something irrelevant, but that pipe just flat out pulls big props at big rpm and being short. Not finicky at all, just works. I run mine at 10 1/8" with an Octura 1455/2 pitched to 3.2" AA45 in a Mutt.

Rob, how do you like your AA45? Are you runnin the ramped intake version? The reason im askin is i know my Mac aint gonna last forever, and the way my fuel tank is set up, the carb on my Mac clears the front of the tank.....

glenng · Jan 8, 2011

Bill Gibson said:
Duck899 said:

Ditto on the Mac 10cc aero pipe.... It may seem like something irrelevant, but that pipe just flat out pulls big props at big rpm and being short. Not finicky at all, just works. I run mine at 10 1/8" with an Octura 1455/2 pitched to 3.2" AA45 in a Mutt.

Click to expand...

Rob, how do you like your AA45? Are you runnin the ramped intake version? The reason im askin is i know my Mac aint gonna last forever, and the way my fuel tank is set up, the carb on my Mac clears the front of the tank.....

Al Hobbs can rebuild your mac- as far as I know most AA parts interchange.

FloridaScaleBoater · Jan 8, 2011

Bill,

You know how I feel about those "sewer pipe sized" carbs on Mac's!!!!!

If I were you, I would contact Al Hobbs to see if one of his AA carbs will fit you Mac.

Or figure out how to adapt the OS 40 carb to it. I'm sure Tom can help you with an adapter for a better carb

robertpickard · Jan 8, 2011

Bill you are to long we all are running at 10 3/8

Duck899 · Jan 8, 2011

Bill Gibson said:
Duck899 said:

Ditto on the Mac 10cc aero pipe.... It may seem like something irrelevant, but that pipe just flat out pulls big props at big rpm and being short. Not finicky at all, just works. I run mine at 10 1/8" with an Octura 1455/2 pitched to 3.2" AA45 in a Mutt.

Click to expand...

Rob, how do you like your AA45? Are you runnin the ramped intake version? The reason im askin is i know my Mac aint gonna last forever, and the way my fuel tank is set up, the carb on my Mac clears the front of the tank.....

I luv the AA45. I won the 45 rigger class with my Sport 40 this year. I run the straight version. Its an awesome engine from an awesome guy. Can't wait for the 67 to come out....

NITROSNIFER · Jan 8, 2011

I run my PT40 with a CMB rs and and AB parabolic at 8.75 inches with a x447 pitched a little. She fly's and has no throttle issues.

29tunnel · Jan 8, 2011

I'm still fast with an ops disk, a little "tlc" add an old ops.67 pipe with the stinger at .280. Finish off with a P.T SP 40 and it will turn a 450 all day. Try a 52 x 64 reduced and hold on. This is a very reliable set up and only lets me down when I forget to fill the tank.

29tunnel · Jan 8, 2011

Forgot the pipe length, 10 1/2 to 3/4

robertpickard · Jan 9, 2011

Bill forgot to tell you he is in Florida like i said anyone here in Florida is running there pipes at 10 3/8

shoboat · Jan 9, 2011

Don,

That is a very good set up on a Sport 40.

We run the parabolic or aero pipe as short as possible.

Mark Sholund

Tim Kish · Jan 9, 2011

29tunnel said:
I'm still fast with an ops disk, a little "tlc" add an old ops.67 pipe with the stinger at .280. Finish off with a P.T SP 40 and it will turn a 450 all day. Try a 52 x 64 reduced and hold on. This is a very reliable set up and only lets me down when I forget to fill the tank.

Don

I think you meant .380 on the stinger I.D. and yes Don's boat is very competetive with the little old OPS .

After watching your boat this past season I would suggest you mark were your strut is and start lowering it a little at a time , I think you will like what you see

.

Also the x450 three blade with the tips bent works very well once you get the right pipe length and strut depth.

Tim K

Bill Gibson · Jan 9, 2011

GeorgiaScaleBoater said:
Bill,

You know how I feel about those "sewer pipe sized" carbs on Mac's!!!!!

If I were you, I would contact Al Hobbs to see if one of his AA carbs will fit you Mac.

Or figure out how to adapt the OS 40 carb to it. I'm sure Tom can help you with an adapter for a better carb

YEP! It runs very much the same way my Scale boat ran with the Mac 67.....ALL or NOTHIN! I will contact Al....see what he has to say 'bout it! I just want the thing to be reasonably easy to tune....it really runs good when its right, but its either up front or dead in the water! Nothin in between.....

SayMikey · Jan 9, 2011

Bill Gibson said:
GeorgiaScaleBoater said:

Bill,

You know how I feel about those "sewer pipe sized" carbs on Mac's!!!!!

If I were you, I would contact Al Hobbs to see if one of his AA carbs will fit you Mac.

Or figure out how to adapt the OS 40 carb to it. I'm sure Tom can help you with an adapter for a better carb

Click to expand...

YEP! It runs very much the same way my Scale boat ran with the Mac 67.....ALL or NOTHIN! I will contact Al....see what he has to say 'bout it! I just want the thing to be reasonably easy to tune....it really runs good when its right, but its either up front or dead in the water! Nothin in between.....

Maybe Phil Thomas will jump in here,he runs a Mac I run a Picco both are darn close. I like my Parabolic set near 10 to 10 1/4

29tunnel · Jan 9, 2011

Thanks Tim, you're right .380 is the I.D. of the stinger. I shimmed it down with some brass tube. I'll try your suggestion for the strut, it should help settle it down a little.

Sport 40 pipe length

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