1/6th Scale Winston Lobster

[Stuart Barr]

Stu,

I've got two of these gas engines from you, just about to put them into 1/6 scale ML boats, any special note  of using them from you would be appreciated  

Gilbert 

Gilbert,

As others have mentioned, you need to run these motors using square drive.  It does not matter if you run square at motor or strut.  The reason is the motors do not have a bearing clip on front housing (housing by flywheel) to keep front bearing being pushed into motor.

CMB recommends 98 octane or above with 8 to 10% oil.  I started with 100LL and now use 110 octane.

The CMB aluminum pipe is the best pipe for this motor.  Hot Pipes work very well, but I found not very durable.  I tried one of the new steel muffled pipes from CMB and it seemed to run well but, it was very heavy.

I never ran the barrel type carb.  The modified Walbro 929, CMB Alpha EVO and new CMB EVO 2 carbs work very well.  If you choose the EVO 2 carb, you need to get a new backplate to hold the carb.  I had an occasion to bench start one of the ALPHA motor like yours with the barrel carb and it seemed to run very well.

Stu

 

[Stuart Barr]

Thanks, I was thinking able buying one until someone told me they were having problems with the cmb Alpha gas engine.

Roger,

CMB went through at least 2 generations of cranks for the ALPHA's.  The 2016 crank solved the problem.  All the ALPHA's I sold had this crank (2016) installed in them.  Crank is very durable now and seemed to take my abuse.  

Stu 

 

[Gilbert Pun]

Gilbert,

As others have mentioned, you need to run these motors using square drive.  It does not matter if you run square at motor or strut.  The reason is the motors do not have a bearing clip on front housing (housing by flywheel) to keep front bearing being pushed into motor.

CMB recommends 98 octane or above with 8 to 10% oil.  I started with 100LL and now use 110 octane.

The CMB aluminum pipe is the best pipe for this motor.  Hot Pipes work very well, but I found not very durable.  I tried one of the new steel muffled pipes from CMB and it seemed to run well but, it was very heavy.

I never ran the barrel type carb.  The modified Walbro 929, CMB Alpha EVO and new CMB EVO 2 carbs work very well.  If you choose the EVO 2 carb, you need to get a new backplate to hold the carb.  I had an occasion to bench start one of the ALPHA motor like yours with the barrel carb and it seemed to run very well.

Stu

Stu,

Thanks for the information, it is very useful, would you please send me two sets of the modified Walbro 929 new CMB EVO 2 carbs with new backplates, I guess you said it seemed to take any abuse in the following message?

Gilbert

 

[Stuart Barr]

Stu,

Thanks for the information, it is very useful, would you please send me two sets of the modified Walbro 929 new CMB EVO 2 carbs with new backplates, I guess you said it seemed to take any abuse in the following message?

Gilbert

Gilbert,

I will have to order the modified Walbro carbs.  Not sure how quick I can get these in.  I have the new EVO 2 carbs and backplates in stock. 

Let's take this off this thread and communicate by email  now.  My email is [email protected].

Thanks,

Stu

 

[Gilbert Pun]

Gilbert,

I will have to order the modified Walbro carbs.  Not sure how quick I can get these in.  I have the new EVO 2 carbs and backplates in stock. 

Let's take this off this thread and communicate by email  now.  My email is [email protected].

Thanks,

Stu

Don't want to hijack this thread, but try to make sure the CMBs are running great in the ML 1/6 scale boats.

Will talk separately.

Gilbert

 

[David Bryant]

A couple hr's in the machine shop and the engine mounts are almost done, going to add some lightning holes later this close enough for mocking of the stuffing box tube & strut installation

View attachment 98158

View attachment 98163

Hello Stu & Tom:

Is this the latest version of the CMB Alpha 27cc EVO engine? (CMB 27cc Alpha EVO-2?). Does this model (in the picture have the updated carb?

Would be nice if someone could create a new thread to document the CMB 27cc Alpha EVO engine (I searched this site "IntlWaters" but don't see much mention about it?). I've been interested in purchasing, but not enough info out there on detail's- ie. how to properly set-up, or what issues, etc.,...

Thanks,

Dave

 

[TomGracey]

Yes latest Version and Carb

I have yet to finish this build so have no other info on the latest Version CMB 27 EVO other then what Stu gave me during the purchase on how to set up the drive line so as not to apply a thrust load to the crank bearing's,  and a starting length of the tuned pipe and needle valve settings for the tillotson Carb.  which BTW is huge (18mm venture) compared to the wilbro carb on the RCMK or Zenoah's 13 mm ventures

Sure if you call Stu he can answer any ?? U might have



Here is how I set up the strut and  prop shaft 1/4 Square drive to 1/4 prop shaft thrust bearing between prop and drive dog (have to finish cutting Prop shaft to length). Round 1/4 collet on he engine end

 

[Stuart Barr]

Dave,

Give me a call if I can help you. (317-462-9978)

Stu

 

[Stuart Barr]

Tom,

You will need to add more bolts to hold the strut blade.  My strut has 3 10-32's to keep the strut stationary.

Stu

 

[TomGracey]

Tom,

You will need to add more bolts to hold the strut blade.  My strut has 3 10-32's to keep the strut stationary.

Stu

Are u talking in the mounting angles or the vertical strut blade

 

[Stuart Barr]

Are u talking in the mounting angles or the vertical strut blade

Put two more bolts holding the strut blade where there is only one now.

Stu

 

[TomGracey]

Put two more bolts holding the strut blade where there is only one now.

Stu

That's what I thought just wanted to ma sure

 

[David Bryant]

Dave,

Give me a call if I can help you. (317-462-9978)

Stu

thanks Stu, I will call you (was getting through the whole Christmas thing, meant to contact you you earlier)

 

[David Bryant]

Yes latest Version and Carb

I have yet to finish this build so have no other info on the latest Version CMB 27 EVO other then what Stu gave me during the purchase on how to set up the drive line so as not to apply a thrust load to the crank bearing's,  and a starting length of the tuned pipe and needle valve settings for the tillotson Carb.  which BTW is huge (18mm venture) compared to the wilbro carb on the RCMK or Zenoah's 13 mm ventures

Sure if you call Stu he can answer any ?? U might have

View attachment 98438

Here is how I set up the strut and  prop shaft 1/4 Square drive to 1/4 prop shaft thrust bearing between prop and drive dog (have to finish cutting Prop shaft to length). Round 1/4 collet on he engine end

View attachment 98439

Thanks Tom. I (sort of) understand the approach. But can't see which part of prop-shaft is square cut? 

 

[Hydro Junkie]

The square cut part would be the flex shaft at one or both ends and the couplers, the ferrile or collet  It would either be soldered into the ferrile and floating in the collet or left floating at the ferrile and clamped into the collet.  Either way, it will eliminate binding at the engine bearings

 

[TomGracey]

Thanks Tom. I (sort of) understand the approach. But can't see which part of prop-shaft is square cut? 

The prop shaft Ferrule is Sq drive

 

[David Bryant]

The square cut part would be the flex shaft at one or both ends and the couplers, the ferrile or collet  It would either be soldered into the ferrile and floating in the collet or left floating at the ferrile and clamped into the collet.  Either way, it will eliminate binding at the engine bearings

ah-haa! I see, thanks!

The prop shaft Ferrule is Sq drive

View attachment 98461

View attachment 98463

thanks for posting Tom, a big help. Did'nt realize there were square-cut ferrule's. Who sells this hardware? (.250 OD square-cut flex-shaft and .250 ID square-cut ferrule)? 

So, in this scenario, we would need to trim the square-cut flex-cable end to the necessary length (which telescope's into ferrule). Do we need to tin (silver-solder) the trimmed portion of the square-cut flex-cable? Or just leave un-tinned?  

 

[TomGracey]

ah-haa! I see, thanks!

thanks for posting Tom, a big help. Did'nt realize there were square-cut ferrule's. Who sells this hardware? (.250 OD square-cut flex-shaft and .250 ID square-cut ferrule)? 

So, in this scenario, we would need to trim the square-cut flex-cable end to the necessary length (which telescope's into ferrule). Do we need to tin (silver-solder) the trimmed portion of the square-cut flex-cable? Or just leave un-tinned? 6 of 1  1/2 doz of the other its a personal choice.    Buy double ended Sq drive cables cut of the engine end for round collet paying attention to the lay of the cable.

 

[David Bryant]

View attachment 98466

View attachment 98467

Appreciate the info Tom. I will contact Dave (@HyperFormance). Looks like I will need:

01-quan .250 flex-shaft, w/square-cut on one end

01-quan .250 ferrule w/square-cut 

 

[David Bryant]

Gilbert,

As others have mentioned, you need to run these motors using square drive.  It does not matter if you run square at motor or strut.  The reason is the motors do not have a bearing clip on front housing (housing by flywheel) to keep front bearing being pushed into motor.

CMB recommends 98 octane or above with 8 to 10% oil.  I started with 100LL and now use 110 octane.

The CMB aluminum pipe is the best pipe for this motor.  Hot Pipes work very well, but I found not very durable.  I tried one of the new steel muffled pipes from CMB and it seemed to run well but, it was very heavy.

I never ran the barrel type carb.  The modified Walbro 929, CMB Alpha EVO and new CMB EVO 2 carbs work very well.  If you choose the EVO 2 carb, you need to get a new backplate to hold the carb.  I had an occasion to bench start one of the ALPHA motor like yours with the barrel carb and it seemed to run very well.

Stu

Hi Stu:

Which (110 octane) fuel are you guys using? Are you mixing your own? Just wondering if there are (off-the-shelf) product out there