OS 9 b

[David Bryant]

The older CMB 67 greenheads came with a lame carb that had no low end fuel adjustment and were better suited for riggers. Guys would replace them with OS9B's because of this and the OS flowed more air on the top end. Out here in the northwest, the guys will crawl along at 5-10mph during mill to get the inside. The OS carb allowed that to be done. The new CMB carb now has a low end needle and works as good as the OS unit. I have the CMB carb on my Bardahl and it will crawl along and then instantly get up and go for the start of a heat race.

Here is a video showing how slow the boats go from 15 seconds to the start.

https://www.youtube.com/watch?v=d1i5lD5ZrRU&list=FLulcj8nLfOEv2cBSw7B05FQ&index=44

so, ultimately, sounds like the O.S. 9B would have a slight edge over the stock CMB .67HR/.80HR carb? Being that the O.S. 9B flows more air at top-end (and could even be improved with bell-mouth mod)? Even though the current .67HR/.80HR has updated low-end needle?

I have brand-new CMB .80HR engines (green-head & blue-head)

Dave, the 9B I have on my CMB 80HR is bored out to .470. Have not tried it yet, hard water. Single F hydro.

interesting. I just grabbed one of the last of Mr. Orlic's NovaRossi .46DD carb's (.470 bore). Was gonna attempt to retro-fit to CMB .80HR?

 

[David Bryant]

can anyone confirm whether the CMB .91/1.01(RS or VAC) carb body interchanges with the CMB .67/.80HR rear-plate mounting surface?

 

[XtremeRcBoats]

I don't think it will fit. I got a OS9b carb with a custom rear plate for my 91RS. Havn't tested it yet, but got a os9b on my older 90Evo engine and it runs pretty good.

 

[David Bryant]

I don't think it will fit. I got a OS9b carb with a custom rear plate for my 91RS. Havn't tested it yet, but got a os9b on my older 90Evo engine and it runs pretty good.

thanks, nice rear-plate fabrication