CMB Motor Question

[Dempsey15]

Hey guys, I have a question about the case and mount size on CMB engines. First of all this is going into a play boat so I am not trying to meet any kinds of racing class with this set up.

My question is, Are the case and mounts the same for the .67 .80 and the new .91HR (this is the new small block 91 not the big one)

I am wondering if I build the boat with a .67 or .80 would I be able to switch to the .91 without rebuilding or moving things around. Obviously the prop will change but as far as stuffing tube, ect.

Thanks in advance for help on this.

Todd

 

[steve wood]

91 will not fit in same mount as 67/80

 

[Dempsey15]

91 will not fit in same mount as 67/80

What about the new .91 HR. its in a smaller case then the .91 RS.

 

[Don Ferrette]

Hey guys, I have a question about the case and mount size on CMB engines. First of all this is going into a play boat so I am not trying to meet any kinds of racing class with this set up.
My question is, Are the case and mounts the same for the .67 .80 and the new .91HR (this is the new small block 91 not the big one)

I am wondering if I build the boat with a .67 or .80 would I be able to switch to the .91 without rebuilding or moving things around. Obviously the prop will change but as far as stuffing tube, ect.

Thanks in advance for help on this.

Todd

Todd the 67/80 bolt pattern is the same & if you go up one size on the mounting ear holes on a 91RS & widen the mount spacing you can squeak it on the same rails but I would just change the mount. The 91HR is not a "small block", it is it's own animal on width & fore/aft hole spacing. Both CMB 91's will require stuffing tube length changes. I do know that when Andy gets the A/A Pro motors out his 91 will be a "small block" that will share the 67/80 pattern so that is something to keep in mind for "the future". The CMB greenhead 67HR is a rock solid strong performer, the 80RS-H needs a little help to live but Stu Barr seems to have something going on that with honing the sleeves. I'm sure he would be happy to share the details with you. B)

 

[Dempsey15]

Hey guys, I have a question about the case and mount size on CMB engines. First of all this is going into a play boat so I am not trying to meet any kinds of racing class with this set up.
My question is, Are the case and mounts the same for the .67 .80 and the new .91HR (this is the new small block 91 not the big one)

I am wondering if I build the boat with a .67 or .80 would I be able to switch to the .91 without rebuilding or moving things around. Obviously the prop will change but as far as stuffing tube, ect.

Thanks in advance for help on this.

Todd

Todd the 67/80 bolt pattern is the same & if you go up one size on the mounting ear holes on a 91RS & widen the mount spacing you can squeak it on the same rails but I would just change the mount. The 91HR is not a "small block", it is it's own animal on width & fore/aft hole spacing. Both CMB 91's will require stuffing tube length changes. I do know that when Andy gets the A/A Pro motors out his 91 will be a "small block" that will share the 67/80 pattern so that is something to keep in mind for "the future". The CMB greenhead 67HR is a rock solid strong performer, the 80RS-H needs a little help to live but Stu Barr seems to have something going on that with honing the sleeves. I'm sure he would be happy to share the details with you. B)

Don, thanks for the info about the HR. I have an old dumas Skater that was originally built for a .67. I like overpowering things and trying to make them as fast as i can. Once i saw the new .91 i thought it would be a cool option. So out of the 67 and 80 I am guessing the 67 is still the better option even thought its smaller?? What is this motor that Andy has?? I might be intrested in looking at one. Thanks

Todd

 

[Don Ferrette]

Hey guys, I have a question about the case and mount size on CMB engines. First of all this is going into a play boat so I am not trying to meet any kinds of racing class with this set up.
My question is, Are the case and mounts the same for the .67 .80 and the new .91HR (this is the new small block 91 not the big one)

I am wondering if I build the boat with a .67 or .80 would I be able to switch to the .91 without rebuilding or moving things around. Obviously the prop will change but as far as stuffing tube, ect.

Thanks in advance for help on this.

Todd

Todd the 67/80 bolt pattern is the same & if you go up one size on the mounting ear holes on a 91RS & widen the mount spacing you can squeak it on the same rails but I would just change the mount. The 91HR is not a "small block", it is it's own animal on width & fore/aft hole spacing. Both CMB 91's will require stuffing tube length changes. I do know that when Andy gets the A/A Pro motors out his 91 will be a "small block" that will share the 67/80 pattern so that is something to keep in mind for "the future". The CMB greenhead 67HR is a rock solid strong performer, the 80RS-H needs a little help to live but Stu Barr seems to have something going on that with honing the sleeves. I'm sure he would be happy to share the details with you. B)

Don, thanks for the info about the HR. I have an old dumas Skater that was originally built for a .67. I like overpowering things and trying to make them as fast as i can. Once i saw the new .91 i thought it would be a cool option. So out of the 67 and 80 I am guessing the 67 is still the better option even thought its smaller?? What is this motor that Andy has?? I might be intrested in looking at one. Thanks

Todd

The new motors from Andy will hopefully start being released during the latter part of this season. Now that they finally got the MAZAK straightened out, Andy has been crankin' out parts, I just ordered some of the new rudder blades to try. Like I said the CMB67 has no real issues but like I said Stu seems to have found something that helps the 80RS-H, time will tell soon enough. B)