MAC 84 VS CMB 80 CASE

[rbarile]

Cracked a mac 84 case actually a few over the years. My question is would a cmb 80 case accept the mac 84 internals. I know the stroke is 1mm longer on the mac, but will the mac crank fit the bearing is my main concern.

The sleeve i can do a shim under the lip. The liner I think will fit??

appreciate the input , thanks Rich B.

 

[bermudadude]

lots of work.

the matching of ports and shimming is a start.

the case bottom has to be opened for the rod/crank to swing the bottom stroke. then theres the drum housing

 

[Andy Brown]

Richie,

With your ability, It would be easier to bore a MAC 67 case to accept the 84 sleeve. The 67 case is easy to come by. I have done this with good results.

 

[Samuel Hagan JR]

Are the 67 and 84 Rods the same?

 

[Jeff Lutz]

Cracked a mac 84 case actually a few over the years. My question is would a cmb 80 case accept the mac 84 internals. I know the stroke is 1mm longer on the mac, but will the mac crank fit the bearing is my main concern.

The sleeve i can do a shim under the lip. The liner I think will fit??

appreciate the input , thanks Rich B.

. If you choose Andy’s suggestion on boring a Mac 67 case, when opening up the port passages, don’t hog the case on a straight angle forward like the Mac was it will just crack again. Arch radius the transfer passages towards the rotor at the bottom some to keep some meat at the bottom of the case similar to the older 100 cmb big block passage shape if you ever saw them.

 

[Jeff Lutz]

Are the 67 and 84 Rods the same?

. Yes

 

[Samuel Hagan JR]

Are the 67 and 84 Rods the same?

. Yes

What about the head buttons. I have a MAC 67 that is very used up. P/S and headbutton are toast but everything else is good.

 

[rbarile]

lots of work.

the matching of ports and shimming is a start.

the case bottom has to be opened for the rod/crank to swing the bottom stroke. then theres the drum housing

lots of work.

the matching of ports and shimming is a start.

the case bottom has to be opened for the rod/crank to swing the bottom stroke. then theres the drum housing

lots of work.

the matching of ports and shimming is a start.

the case bottom has to be opened for the rod/crank to swing the bottom stroke. then theres the drum housing

Will the mac crank fit in the bearings and line up to the rod ?? And the sleeve, slip in properly?? Boring the case no problem . Is the bolt pattern for the back end the same?? Dont have cmb case on hand trying to see if its worth the effort.

 

[rbarile]

Richie,

With your ability, It would be easier to bore a MAC 67 case to accept the 84 sleeve. The 67 case is easy to come by. I have done this with good results.

mac 67 case gets too hard to line up porting after the bore procedure especially front transfer near exhaust , tried it once. Have to take out alot of

case material. Exhaust going to pipe is smaller also, as you bore out the case the transferes and boost walls become further apart alot of work.

all intake tracts are smaller on the 67 going to outer part of case.

With the cmb going up on the port 1mm shouldnt be too much?? IF crank and rear end bolt pattern are the same good might work with out to much work??

 

[rbarile]

Richie,

With your ability, It would be easier to bore a MAC 67 case to accept the 84 sleeve. The 67 case is easy to come by. I have done this with good results.

mac 67 case gets too hard to line up porting after the bore procedure especially front transfer near exhaust , tried it once. Have to take out alot of

case material. Exhaust going to pipe is smaller also, as you bore out the case the transferes and boost walls become further apart alot of work.

all intake tracts are smaller on the 67 going to outer part of case.

With the cmb going up on the port 1mm shouldnt be too much?? IF crank and rear end bolt pattern are the same might work with out to much work??

 

[Michael Costanzo]

richie,just send the cases to Tom Foley or myself and get them TIG welded and call it a day,mikie.

 

[Samuel Hagan JR]

What does that do?

 

[rbarile]

What does that do?

Sam sent you a email on your mac 67 How much and can you call me Rich B.