CMB/MAC Part Swap

[kilr95ss]

Will a CMB 21 piston and sleeve fit a MAC 21?

After getting my second hand engine cleaned and back together, there does not seem to be much compression, easily turn the crank past TDC.

 

[kilr95ss]

Well, I just did a search and found this: http://www.twf8.ws/new/tech/engine/cmb/int...gentpiston.html

Anyone have a opinion on it?

 

[Richard Dahlheimer]

Well, I just did a search and found this: http://www.twf8.ws/new/tech/engine/cmb/int...gentpiston.html
Anyone have a opinion on it?

Yes, the CMB green head Valvola, and the first Red head Valvola piston and sleeve will work fine in your MAC .21 blue head. Richard D

 

[Josh Stollfuss]

I put a piston and sleeve from a CMB .21 Valvoa in my Mac .21 last year. No difference between the two, it works great.

Josh-

 

[Andy Greene]

Would the same hold true for the .45 motor as well ???

 

[Bob Finn]

No. The 45's are not the same at all.

 

[Andy Greene]

No. The 45's are not the same at all.

How did I already have a feeling I knew that answer. I need a piston and sleeve, zammm

 

[Don Ferrette]

No. The 45's are not the same at all.

How did I already have a feeling I knew that answer. I need a piston and sleeve, zammm

Is the sleeve damaged??

 

[Andy Greene]

No. The 45's are not the same at all.

How did I already have a feeling I knew that answer. I need a piston and sleeve, zammm

Is the sleeve damaged??

Its seems to be okay, it has been squeezed a time or too. But mainly getting a little scarring on the piston and it just doesnt have the thump it used too. I hate to ditch the liner as A/B has done a little trimming on it.

 

[Don Ferrette]

No. The 45's are not the same at all.

How did I already have a feeling I knew that answer. I need a piston and sleeve, zammm

Is the sleeve damaged??

Its seems to be okay, it has been squeezed a time or too. But mainly getting a little scarring on the piston and it just doesnt have the thump it used too. I hate to ditch the liner as A/B has done a little trimming on it.

Send the piston & sleeve to Brad Christy & have him make a piston for it. He also can hone the sleeve. Brad just did a set of pistons & sleeve honing for a pair of MAC84's for me that are superb.

 

[Andy Greene]

No. The 45's are not the same at all.

How did I already have a feeling I knew that answer. I need a piston and sleeve, zammm

Is the sleeve damaged??

Its seems to be okay, it has been squeezed a time or too. But mainly getting a little scarring on the piston and it just doesnt have the thump it used too. I hate to ditch the liner as A/B has done a little trimming on it.

Send the piston & sleeve to Brad Christy & have him make a piston for it. He also can hone the sleeve. Brad just did a set of pistons & sleeve honing for a pair of MAC84's for me that are superb.

Thanks for the tip Don. Any other go fast goodies you would rec. while its apart ??

 

[Don Ferrette]

No. The 45's are not the same at all.

How did I already have a feeling I knew that answer. I need a piston and sleeve, zammm

Is the sleeve damaged??

Its seems to be okay, it has been squeezed a time or too. But mainly getting a little scarring on the piston and it just doesnt have the thump it used too. I hate to ditch the liner as A/B has done a little trimming on it.

Send the piston & sleeve to Brad Christy & have him make a piston for it. He also can hone the sleeve. Brad just did a set of pistons & sleeve honing for a pair of MAC84's for me that are superb.

Thanks for the tip Don. Any other go fast goodies you would rec. while its apart ??

fresh bearings. B)

 

[FloridaScaleBoater]

Get all you can dude!

Mike will be back soon!

Will you make it to Orlando? Don't know if Mike will make that one or not? I will be there though

Rick

 

[kilr95ss]

Thanks for the info, what about the article on the way the MAC piston is designed to fit in the sleeve properly once the engine is at operating temperature? From the article my piston and sleeve fitment is correct.

 

[Tofastformellow]

Gday,

would the HR91 piston and sleve fit into my tired old mc 67 ??

they look similar in engine size?? similar in porting too!!

if not i really want to get a mac 84 piston and liner for it ... when andy gets some new parts

but a HR91 setup would get me going again..

]

will it fit ???

thanks

jason

 

[tnrcboatracer]

I believe that the MAc 67 and 84 sleeves have different OD's, so no, the 64 sleeve won't fit in a 67 case. The casting on the 67 and 84 are the same, but the cylinders are bored differently. I don't know about the HR91.......

 

[Tofastformellow]

ok thats news to me ..

i thought they were the same bore , just a thicker sleave for the 67...

ok..



Jason

 

[Don Ferrette]

ok thats news to me ..
i thought they were the same bore , just a thicker sleave for the 67...

ok..



Jason

Jon is correct, the MAC67 & 84 cases are different bore sizes.

 

[Tofastformellow]

ok thats news to me ..
i thought they were the same bore , just a thicker sleave for the 67...

ok..



Jason

Jon is correct, the MAC67 & 84 cases are different bore sizes.

:unsure: :unsure: :unsure: <_< <_< <_< :huh: :huh: :angry: :blink:

sighhh

the wait goes on..

Jason

 

[waltr]

ok thats news to me ..
i thought they were the same bore , just a thicker sleave for the 67...

ok..



Jason

Jon is correct, the MAC67 & 84 cases are different bore sizes.

:unsure: :unsure: :unsure: <_< <_< <_< :huh: :huh: :angry: :blink:

sighhh

the wait goes on..

Jason

Jason,

As Don has stated in an earlier post, It your sleeve is still decent,send the sleeve off to Brad Christy and he can make you a new piston and hone the sleeve. Brad does a FANTASTIC job on pistons. He recently did a Picco 45 Blackhead for me and it is beautiful.

I'm sure you won't be dissapointed.