CMB .67 IN SPRINT CAT 36

[shawn sibley]

i have a sprint cat 36 with a cmb green head .67 with 3rd needle valve and prop on it now is a X450 and the boat gps'ed at 43 (I NEED HELP)

any help on prop size would be nice and when running 50% nitro what plug cold or med hot and how many turns out should that needle come out...

thx

 

[piper_chuck]

X450 sounds too small. I ran my 36" sprintcat with an OS .81. I stopped running it last fall and sold off everything above a .45, so I'm going from memory, but I think the prop it ended up happiest with was a two blade X457.

 

[Ray Sametz]

Shawn, Mark Shouland did up a ABC 57X73 for my cat, great all around prop. I use a MC-9 glow plug on 50% nitro. Chuck mentioned a good prop X457, I can push a X460 only at sea level with good air. Enjoy, Hammer B) B)

 

[Roxyflash]

The 457/2 is a good prop for it.If you have a real strong motor a 460/2 is great.My cmb 67 wouldnt pull the 460 but my old picco does pushing the boat to 60mph.I run the big fat belly CMB 67 pipe at 12 inches long.I also run 60% nitro.

 

[john v]

i have the 36" sprint cat with the 175$ twin plug cmb ,67 that tidewater had on sale. did a lot of porting work to get a good numbers match. i run a worked oct 462 and the best run was at 62mph. i run this boat in dist 11 in open hyd and placed first in 2 races. the motor is timed so high that i have no low end torque no matter what pipe length but once its on plane no one comes close. the green head is an improved version of my motor and should have some good numbers( maybe check head clearance) the guys on iw can give you some more tips on that motor. when your boat is dialed in this will turn into your favorate boat, i always get good comments when mine runs. john v

 

[shawn sibley]

I tryed a x460 and the 3rd ch needle valve about 1turn out and still only got 44 on the gps has great take off just no top end I leaned it out and still ran the same are these needle valves no good any help plez

 

[Ray Sametz]

I tryed a x460 and the 3rd ch needle valve about 1turn out and still only got 44 on the gps has great take off just no top end I leaned it out and still ran the same are these needle valves no good any help plez

What's your pipe lenght, I ran at 10-1/4 with a MAC pipe and a X460??

 

[shawn sibley]

I tryed a x460 and the 3rd ch needle valve about 1turn out and still only got 44 on the gps has great take off just no top end I leaned it out and still ran the same are these needle valves no good any help plez

What's your pipe lenght, I ran at 10-1/4 with a MAC pipe and a X460??

Ok how do i check pipe size from where to where becuse it looks like its atleast 15=16 inches it looks huge...heres a picture thats how i got it

 

[Ray Sametz]

Shawn, measure from center of cylinder to seam in a straight line. Let us know what you get???

 

[shawn sibley]

I tryed a x460 and the 3rd ch needle valve about 1turn out and still only got 44 on the gps has great take off just no top end I leaned it out and still ran the same are these needle valves no good any help plez

What's your pipe lenght, I ran at 10-1/4 with a MAC pipe and a X460??

Ok how do i check pipe size from where to where becuse it looks like its atleast 15=16 inches it looks huge...heres a picture thats how i got it

ok looking at the pipe its was like 16' form the plug to weld but i took the blue cupler off and notice that the header fits in the pipe is that how it goes if i do that i can get the pipe down to 10 1/4' inch so i tryed it and the boat went 48 on the gps with a cold plug (o'donald ss cold)anyone have any ideas and as you can tell i am new to tuning boats... car/trucks i can do allday but not boats not yet thx for help guys

 

[Ray Sametz]

Start at 11-1/4 inches. Make sure the header does not extend to far into the pipe, you may have to cut it. You don't want a cold plug with 50%. Work with different props and needle. Shorten pipe as you go. 10-1/4 inches might be to short for your setup. Enjoy B)