cmb 21 red head vs cmb 21 blue head

[bob miller]

will the the ramped up carb and housing from the cmb 21 red head fit onto the cmb 21 blue head ???what if any are the differences between the 21 blue head vs the 21 red head cmb ???....thanks....bob

 

[Bert Dygert]

Bob,

I would go with the new CMB Beta. I hear this is the best 21 motor CMB has come out with. There are a few Beta motors out there currently running in sport 20, 20 mono and 20 rigger showing great potential. The motor has great low end torque. We should see more of them in the future.

Just for the record I have both Red Head Valvola (slant) in a sport 20 hull and a converted Red Head with the VAC carb and drum assembly in a 20 Black Jack rigger. It took a little time to get them right but they both run very well.

I believe Stu Barr has the new Beta 21 in stock.

Regards,

Bert Dygert

 

[Stuart Barr]

Bob,

Customers told me that the "inline induction" (blue head) had more torque. This all depends on what type of load you are putting on the motor.

Stu

 

[tnrcboatracer]

Typically the inline induction setup has lower internal case volume due to the intake tract layout. Which in turn is what gives the increased torque.

 

[bob miller]

so apparently there is no major differences between the blue head cmb 21 and the red head cmb 21....

 

[shoboat]

Bob,

What kind of boat are you going to be running this motor in?

The Beta-21 will out perform most of the other stock 21 motors out of the box.

The best 21 motor CMB has made in years.

Thanks,

Mark Sholund

 

[bob miller]

I'm running a aeromarine 21 size cat , I tried to use the 21 cmb red head . very little success , a friend offered his 21 cmb blue head , it wont fit because it is too long , I asked if the ramp up carb and assembly from the red head would fit the blue head motor but so far no one has said yes or no....bob

 

[bob miller]

at this time I don't plan on buying another motor....bob

 

[dwilfong]

Thy all inter change. I run a blue head VAC intake on my MAC and my CMB green head.

The P/L also inter change with just some small cuting at the ex port of the case for the 3 port ex.

 

[FloridaScaleBoater]

I'm running a aeromarine 21 size cat , I tried to use the 21 cmb red head . very little success , a friend offered his 21 cmb blue head , it wont fit because it is too long , I asked if the ramp up carb and assembly from the red head would fit the blue head motor but so far no one has said yes or no....bob

Bob, What vintage red head Valvola do you have? Did you buy it new, from someone like Stu Barr?

Reason I ask, for a breif time, the piston and sleeve's supplied with that particular run of engines, the sleeve had some "whackey" numbers and if you had purchased the engine from Stu, the engine came with a new, correctly timed piston & sleeve.

Ask Stu about how to identify the bad sleeve vice the good sleeve

This MAY be the reason your not having success with you particular engine.

As far as adapting the red head Valvola intake to the VAC engine, contact Mark Grim.

If it can be done, Mark would know.

Mark Grim

714-890-3127 [email protected]

 

[dwilfong]

the RS7 three port ex is a good sleeve. the one port ex not so much.

The new Bata 3 port ex so far has worked very good. Just need more time to loosen it up to realy tell.

 

[bob miller]

I bought the cmb21 red head used , i.ll talk to stu about porting numbers....bob

 

[Bert Dygert]

Bob,

Because I have put the 21 VAC drum and carb assembly on the older slant (Valvola) I don't see why you couldn't go the other way and put the Vavola drum and carb on the VAC. I have an new RSV07 motor that came from the factory with the VAC set-up. I also have that same RSV block with the slant assembly before the VAC was available.

Regards,

Bert Dygert

 

[JoachimRuess]

Bob, the valves from RS 7, Mac, Vac and Beta are interchangeable.

Look at the CMB Beta treat, there is a video from my rigger with beta and old Mac valve.

Regards

Joachim

 

[Steve P]

Will the P/L from the new Beta fit in the Red head 21 (RSV07). I would like to know how to check the sleeve to see if I have one with the "wacky #s" I also bought it from another boater.

 

[dwilfong]

Guys I will take some picks and post the measurement here when get a chance.

Have MAC, Single port ex CMB ,3 port ex CMB and a new Beta that I can show the comparison with.

will include measurements from top of liner to the ports.

Gust give me a little.

All the parts will inter change cranks ,rods ,P/L and intake set up.

You can swap back and forth and make many combos with theses eng.

Thy are all based off the MAC.21

You can freshen up any one with parts now available.

For those that don't want to be bothered. Stu will be more than happy to sell you a new Beta then just drop any slant intake on it and go.

 

[Steve P]

Could some one look at this picture and tell me if this is one of the sleeves that had the wrong timing

on it.

Steve