CMB 1.01RS EVO

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Blackout

Well-Known Member
Joined
Sep 10, 2008
Messages
1,610
How is this new engine working out for folks running it in single engine F-Hydro applications? How does it compare to the .91 VAC?

Thanks!
 
The EVO is performing great. Both the 91 and the 101.

Out of the box performance the VAC Is faster.

But my opinion is the RS style motor last longer. But need to be modified to keep up with a tuned VAC.
 
How is this new engine working out for folks running it in single engine F-Hydro applications? How does it compare to the .91 VAC?

Thanks!
If U are putting it in a rigger that weighs 10 LB. or less, I would spend plenty of time breaking it in, non modified, head clearance .010 to .012, I run a .550 carb with .090 spray bar with a multi stage pipe @ 101/2 to 11 inches, pitched up 1667, 60% nitro, if it spools up to fast when U start leaning the third channel down, back the third channel off until U can get a better handle on the peak RPM's before U hurt the engine, if U are breaking in or testing in cool or cold water, less than 70 degrees, U may have to go to a hotter glow plug. If U are putting this engine in a mono, have the piston and liner correctly modded and then do the larger carb and spray bar and fuel and break in.

Moby

JM2CW
 
How is this new engine working out for folks running it in single engine F-Hydro applications? How does it compare to the .91 VAC?

Thanks!
The Big Block CMB engines work well. If the Fuel system can Feed the engine. LARGE Pipe pressure Fitting & 5/32 tubing in fuel tanks With Large Fuel line thru out the Boat. If it is set up correct? you can run a fast piston speed & remain Rich needle while testing.... You DO NOT want a engine set up that comes into its own needle while cycling thru the throttle positions. This Type of Set up is Running Out of Fuel on the Top End piston speed & will cause engine damage..
 
How is this new engine working out for folks running it in single engine F-Hydro applications? How does it compare to the .91 VAC?

Thanks!
Don't mess with the 101 unless you want a steep learning curve . The factory has to fix the fuel starvation problem on this engine , New case casting with much larger intake area IMHO . Otherwise you need to be a modification guru with lots of experience or tutelage from others that have spent the money to learn the hard way .

The VAC 91 will run with any 101 I have seen .
 
The eng is designed for 20% nitro.

Prop it accordingly and It will do what it was designed for with no mods.

High nitro is not always the answer!!!!
 
High nitro is not always the answer!!!!
Amen to that David!
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Thanks for the info!

I'm in this hobby for the challenge. So not always looking for the easiest way.
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Yes..same here, please explain......have a new sitting here and it going in a 44 SD mono...
 
Chuck..... You already know the New RS EVO 91 & 101 engine that Stu is selling is very very close to a out of the Box Race engine........ it needs a little more closing timing on the intake rotor. You Must Cleareance the Center of the intake rotor to float on the crank pin so it can seal on the intake stroke & the compression stroke.. CMB resolved the transfer port size by increasing the port .100 thousands longer. The port & the transfers in the case matches it too. This engine must have the head button increased to 1.0 cc if you plan to run 55-60 nitro & set the squish at .010 .012.. We only cool the top of the cooling head. Most do not use the lower cooling loop. This engine has Way More Power than any other brand or size I have ran........ If CMB really wanted to kick Some ass they need a 105 - 110 Big Bore kit for this engine. as you know they bored the case bigger to make the liner thicker & for piston stability. This now allows a Big Bore kit........
 
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Joe thankyou for the info on the 101 , because of my lack of experience with zimmerman disc engines could you elaborate on the "clearence the center of the intake rotor to float on the crank pin"

David
 
I think what Joe is meaning is the Zim disc drive opening that fits on the end of the crank may be tight and not allow the disc to move slightly to be able to seal on the case . He has lots of time with these engines .
 
Joe thankyou for the info on the 101 , because of my lack of experience with zimmerman disc engines could you elaborate on the "clearence the center of the intake rotor to float on the crank pin"

David
the Zimmerman valve acting as a intake valve on the RS EVO m Engine comes from the factory very tight fit on the crank drive pin. This valve needs a little fileing & fitting to fit gently on the crankshaft drive pin. Just a few strokes with a jewelers file will do the Trick... you want the intake valve Disk to be able to Float on the crank pin so it can seal onto the intake side of the case on the intake stroke & seal to the carb backplate on the compression stroke. This allows for a Good Crankcase Seal & Good Performance Over all..... Someone that does engine work would include this in there engine work or Modification.......
 
Hi Joe,

I know you may not want to give away you secrets on the induction timing but I will ask the question what are your intake timing numbers and do you just do the disc or do you do the case as well.

Thanks Kevin.
 
Hi Joe,

I know you may not want to give away you secrets on the induction timing but I will ask the question what are your intake timing numbers and do you just do the disc or do you do the case as well.

Thanks Kevin.
If you cut the Disk there is No Need to Do the Case..... You actually get the entire timing increase.... If you cut the timing on the Case & Not the Disk? you will have to Match the Case and the carb back plate. The Zimmerman valve is Sucked to the case on the intake stroke...... and Blown or Pushed against the carb backplate on the compression stroke. No More than .005 total valve clearance.........
 
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