Vac 21 Carb On A MAC 21

[Jerry T]

A while back there was a disscussion on the CMB VAC 21 carb and housing on a MAC 21.

Has anyone tried to incorporate a VAC 21 carb, housing, and drum in an older MAC 21 motor...is the intake timing close...or am I chasing.....?

Just asking, have the parts and want to try these things together, also before I go blind trying to get the specs and see if they will work together.

Thanks

Jerry

 

[dave roach]

Jerry

It will work fine.You should see more RPM'S on this set up.

Dave Roach

 

[Jerry T]

Thanks Dave

You are in my prayers for your shoulder surgery.

Hope to see you at Evansville in the spring.

Jerry

 

[dave roach]

Jerry

Are you going out to try this set up.If so let me know how it work for you.

Thanks Jerry

Dave Roach

 

[Jerry T]

Jerry

Are you going out to try this set up.If so let me know how it work for you.

Thanks Jerry

Dave Roach

I have all the stuff so if the rotor timing looks close on the bench, I'll see what happens.

Trouble is the water is getting stiff fast, so it will be in the spring before I get it on the water.

I already run the newer CMB bolt on carb and the newer drum & rotor from the CMB Valvola, seems to scream pretty good already.

I'll keep you posted.

 

[Marty Davis]

Jerry

Are you going out to try this set up.If so let me know how it work for you.

Thanks Jerry

Dave Roach

Dave:

This is what I have been running and it is AWESOME. I have the MAC with the newer CMB liner with the little side eyebrows. That liner had great blow down time (30 degrees). I have one of Brad Christy's flat top pistons in it at 9.25:1 at .006" clearance. It is by far the best 20 engine that I have ever had for a hydro, RPM is off the chart and has terrific torque. Maybe more that you wanted to know

Good luck with the shoulder surgery.....

 

[Jerry T]

Jerry

Are you going out to try this set up.If so let me know how it work for you.

Thanks Jerry

Dave Roach

Dave:

This is what I have been running and it is AWESOME. I have the MAC with the newer CMB liner with the little side eyebrows. That liner had great blow down time (30 degrees). I have one of Brad Christy's flat top pistons in it at 9.25:1 at .006" clearance. It is by far the best 20 engine that I have ever had for a hydro, RPM is off the chart and has terrific torque. Maybe more that you wanted to know

Good luck with the shoulder surgery.....

Marty are you running the new MAC case or the older case. The newer case has more volume than the older case?

In a mono I run .011 head clearance, at .008 I can only get 1 heat out of a plug..

 

[Marty Davis]

Jerry

Are you going out to try this set up.If so let me know how it work for you.

Thanks Jerry

Dave Roach

Dave:

This is what I have been running and it is AWESOME. I have the MAC with the newer CMB liner with the little side eyebrows. That liner had great blow down time (30 degrees). I have one of Brad Christy's flat top pistons in it at 9.25:1 at .006" clearance. It is by far the best 20 engine that I have ever had for a hydro, RPM is off the chart and has terrific torque. Maybe more that you wanted to know

Good luck with the shoulder surgery.....

Marty are you running the new MAC case or the older case. The newer case has more volume than the older case?

In a mono I run .011 head clearance, at .008 I can only get 1 heat out of a plug..

Old case.... I have a head button that has probably more volume than the stock head button so I don't have plug problems.

You have to be careful about plug burning. MANY times it is because the engine is not making much power and has to work very hard. If the engine is on the rich side of the needle, and set correctly (squish) and volume, many times the engine does not have to work hard and the plug stays in very well. The more HP you make the easier the task of the engine.

 

[Jerry T]

Jerry

Are you going out to try this set up.If so let me know how it work for you.

Thanks Jerry

Dave Roach

Dave:

This is what I have been running and it is AWESOME. I have the MAC with the newer CMB liner with the little side eyebrows. That liner had great blow down time (30 degrees). I have one of Brad Christy's flat top pistons in it at 9.25:1 at .006" clearance. It is by far the best 20 engine that I have ever had for a hydro, RPM is off the chart and has terrific torque. Maybe more that you wanted to know

Good luck with the shoulder surgery.....

Marty are you running the new MAC case or the older case. The newer case has more volume than the older case?

In a mono I run .011 head clearance, at .008 I can only get 1 heat out of a plug..

Old case.... I have a head button that has probably more volume than the stock head button so I don't have plug problems.

You have to be careful about plug burning. MANY times it is because the engine is not making much power and has to work very hard. If the engine is on the rich side of the needle, and set correctly (squish) and volume, many times the engine does not have to work hard and the plug stays in very well. The more HP you make the easier the task of the engine.

Gotcha,

Thanks for the info.