cmb 21 induction set ups

[jason jury]

hi fellow boaters just wondering if you can use the new cmb induction styles on an older valvola or mac 21 engine,,all info welcomed thanks jason,

 

[julianconde]

Talk to Stu Barr he can tell you what you can do ok.

julian

 

[dwilfong]

have a small case MAC21 that I am fitting with a CMB VAC intake set up . it dose take a little cutting on the case to unshroud the VAC set up but not that hard to do.

Will see how it runs here in a few weeks.

David

 

[RodneyPierce]

:lol: :lol: :lol: :lol: :lol: Jesus David, what arent you working on??

 

[dwilfong]

RCMK on nitro yet. :unsure:

 

[Bert Dygert]

Jason,

I'm running a 06 Red 21 Valvola motor with the VAC conversion. I had to make no adjustments to the case. But you need to check the clearance on the drum to the crank pin. Also you have to watch the o-ring groove. Get with Stu Barr here on I/W and he can give you all the information you need.

I converted my motor over in june of last year. I all i can say is Wow!!!! Motor is in a 21 Black Jack with a 3280 pipe.

Bert Dygert

 

[Jerry T]

The VAC system works very well on the MAC motors even with no cutting on the case.

The ZOOM Carb from Charles Purdue makes it even better.

 

[LarryConrad]

Several boaters in Europe were going the other way after running the VAC's with less than spectacular results. Fitting the Valvola/Mac drum housings to the VAC's. Maybe Richard Dahlheimer will chime in on this thread He swapped the Red Head Valvola out in his Black Jack for The VAC style engine and couldn't pull as much prop. His engine is the version that CMB released that had parts from the Valvola and the VAC. Over the winter he acquired the parts from Stu to convert it completely to a VAC and also a Zoom carb from Charles.

 

[dwilfong]

I did here some people saying that thy had difficulty in tuning with the stock carb. will be using one of the zoom carbs made for the VAC set up.

You do not have to cut on the case but it will help the pipe draw thew the boost port.

David

 

[dwilfong]

I did here some people saying that thy had difficulty in tuning with the stock carb. will be using one of the zoom carbs made for the VAC set up.

You do not have to cut on the case but it will help the pipe draw thew the boost port.

Also it did take some lapping on the crank pin to get a good fit to the drum.

David

 

[Jerry T]

I have used the Valvola housing and carb on the MAC 21's, but, I used the ramped MAC rotor with them.

You have to modify/remove the ramp in the valvola housing.

So far on the 21 mono I like the VAC setup with the ZOOM carb.

I will try the same set up on the PT Sport 21.soon.

 

[Marty Davis]

I used the VAC front end and stock carb on my MAC and didn't change a thing on the case.

Works perfectly and is better than anything that I have used. The carb works fine. I leave the low speed intact and like having it. Easy to tune and works great.

 

[jason jury]

thanks fellow boaters this info was exactly what i was looking for ,, cheers jase,,