CMB vs MAC

[Lay26]

i don't know if this was discused before, but i got a new scale boat a dumas circus circus and i'm looking for a motor. i know that alot of you guys run both mac 67 and cmb 67 which one is better suited in a scale boat? which do you guys like best?

 

[Russell Bear]

Henry, Can't go wrong with either one however, I hear the MAC with the big carb is working pretty well.

 

[Don Ferrette]

Both are excellent motors. If you go with the CMB, add the OS9B carb. It's a bolt on (with just a slight elongation of carb mounting holes) & way better than the stock carb. My new Bud T-4 will be MAC powered.

 

[TimD]

The green heads go very well with an Exhaust throttle on them too. Venturi is better than the stock carb!

 

[Roy Munoz]

I've been verry happy with my CMB,s in my Scales..And one is a verry heavy Shovelnose..19lbs dry 20.5lb wet,and maybe a little more after a few heats..

 

[[email protected]]

Never owned a MAC, but all my scales are CMB powered and I love them.

 

[gpapag1]

from greece

i have the cmb80 on my 1/8 dumas hydro!runs okey

just dont use the engine mount dumas gives

make your own with rubber for the vibrations.....

the lonly hydro racer here in greece

george....

View attachment 1829

 

[gpapag1]

the boat

View attachment 1830

 

[gpapag1]

can anybody fint out what is this........????

40% more power...

test runs whent okey

View attachment 1831

 

[david cox]

Don:

You mention using the OS9B carb with the green head CMB. Will that carb also work well on the purple head CMB? Why do you think the carb performs better than the stock CMB carb?

Thanks, David

 

[Don Ferrette]

Don:
You mention using the OS9B carb with the green head CMB. Will that carb also work well on the purple head CMB? Why do you think the carb performs better than the stock CMB carb?

Thanks, David

The OS9B will work just as well on a purple head. The 9B is one of the best metering carbs available. Hands down superior to the stock carb, I don't think it, I know it from experience. Been there, done that...........

 

[Ian Inverarity]

Don,

Do you modify the low end needle on the 9B's? Mine didn't transition all that well on the K-90 and when I put it on a flow meter as soon as the needle pulls out of the spray bar at about 1/3 the flow goes to maximum. It wasnt a cheap carb so I haven't been game to modify the needle!!

Ian.

 

[Don Ferrette]

Go to Dave Marles' website & modify the low needle like he shows. It will fix that.

 

[bsmtboy2]

Has anyone tried the Andy Brown aftermarket carbs on the CMB motors yet and if so what were the results? :unsure:

 

[Ian Inverarity]

Don,

Yeah, I have seen Dave's tips, I was wondering if people were doing the mods for oval racing!

Ian.

 

[Don Ferrette]

Ian-

When I fitted the 9B to my CMB90 I experienced the transition problem. Did the re-taper of the low end needle & problem went away. Motor throttles great, crisp & smooth.