CMB VAC 45 data question

[ids987]

Morning all. Just wondered if anyone may know if the VAC 45 case bores are the same size as the HR please ?

Alternatively, does anyone know the o/d of the VAC 45 liner please ?

Many Thanks: Ian

 

[tero juola]

The case bore are same VAC and HR.

 

[ids987]

Thanks muchly for the info. Much appreciated.

I picked up a VAC drum and backplate on eBay recently; thinking I might put it on the HR; recognising that I would need to elongate the drive slot to accommodate the shorter stroke of the HR, but then got to thinking that if the critical dimensions of the crankcase are the same, it might be possible to build a VAC in the HR case.

I could re-use th HR P/S to freshen up one of my purple heads.

I don't suppose you happen to know if the rod dimensions are the same too (big end diameter, small end diameter, rod length) ?

Thanks Again:

Ian

 

[tero juola]

I only to fit VAC liner to HR crankcase, but i can check tomorrow this, engines are workshop(my father home). And i send pm.

Thanks Tero

 

[ids987]

Thanks Tero. Much appreciated.

Did you use the VAC piston and liner with the HR crank and rod ?

 

[tero juola]

PM sent.

 

[Andy Brown]

The VAC uses the longer MAC 45 rod. I think the HR used the shorter rod length of all of the previous CMB 45's. You may have to do some extra shiming on the sleeve depending on which rod you use to get the timing where you want it.

 

[ids987]

The VAC uses the longer MAC 45 rod. I think the HR used the shorter rod length of all of the previous CMB 45's. You may have to do some extra shiming on the sleeve depending on which rod you use to get the timing where you want it.

Thanks Andy - makes sense. The bore and stroke of the VAC are also somewhat similar to the MAC. Slightly longer stroke I think....