CMB .67 question

[JPriami]

My dad decided to buy an engine and might start a project boat. He won it on eBay. But we can’t find much info on the motor online. I think it’s the older one is maybe why. But if anyone is familiar with the engine can the help us out with specs and personal opinion on the engine. It a CMB .67 it has the gold head and a twin glow plug design. It’s never been run and is new still. It came with the motor mount, header, collet and pipe all new as well.

 

[AndyBrown]

If moddifed properly, that is a good engine. If you try to run it in stock form, be prepared for plenty of frustration.

 

[anthony420]

My dad decided to buy an engine and might start a project boat. He won it on eBay. But we can’t find much info on the motor online. I think it’s the older one is maybe why. But if anyone is familiar with the engine can the help us out with specs and personal opinion on the engine. It a CMB .67 it has the gold head and a twin glow plug design. It’s never been run and is new still. It came with the motor mount, header, collet and pipe all new as well.

Score!

 

[JPriami]

If moddifed properly, that is a good engine. If you try to run it in stock form, be prepared for plenty of frustration.

What modifications are need?

Thanks,

 

[steve wood]

If moddifed properly, that is a good engine. If you try to run it in stock form, be prepared for plenty of frustration.

What modifications are need?

Thanks,

set rotor clearance and put in a single plug head. lose the low end needle. that's the way we ran em

 

[Chris Wood]

If moddifed properly, that is a good engine. If you try to run it in stock form, be prepared for plenty of frustration.

What modifications are need?

Thanks,

set rotor clearance and put in a single plug head. lose the low end needle. that's the way we ran em

Rotor clearence needs to be set to .003 thousands.. I foreget what we used to use as a bowl volume.. as dad said loose the dbl plug head.. waste of plugs.. and the sleeves need to be cut up.. used to run 192 on the exhaust.. 134-136 on the boost and transfers.

and if you can.. open the carb up to .500 bore.. dad did it on a WIRE EDM machine but i realize most don't have access to this..

and when you get all that done.. play with a velocity stack on the carb.. we picked up 3-4mph with that..

take in mind this was all done for a hydro.. what type of boat is it going in?

chris

 

[JPriami]

He is looking at deep V hulls. The aeromarine challenger 43 I think.

Thanks for the info. I used to work in a machine shop myself so maybe I can help him with getting some of the stuff mentioned done. He knows some people also.

 

[Scott Norris]

I run one is an old 44" Sightler Mono and it runs verry competive as a heat race boat. Got a pair of motors from Bob Finn and he had already massaged them a bit. Motors are bulletproof.

 

[tnrcboatracer]

So, you're the guy that won that one. I was watching it, too.

 

[piper_chuck]

I run one is an old 44" Sightler Mono and it runs verry competive as a heat race boat. Got a pair of motors from Bob Finn and he had already massaged them a bit. Motors are bulletproof.

And having that extra plug has come in handy once or twice, hasn't it?

 

[anthony_marquart]

I used to run one in a aeromarine cat too. It can be a source of frustration for sure. BUT, that motor will last a LONG time...

 

[JPriami]

Looks like I'll be putting this engine in my sprintcat 40/60 for a while. Let me ask this beofre i cut it. Is the tuned pipe length still supposed to be around 11 to 10 3/4 from the center of the engine to the fat part of the pipe? I understand thats the length for an ops .67 but is it the same for this CMB .67?

 

[Chris Wood]

Looks like I'll be putting this engine in my sprintcat 40/60 for a while. Let me ask this beofre i cut it. Is the tuned pipe length still supposed to be around 11 to 10 3/4 from the center of the engine to the fat part of the pipe? I understand thats the length for an ops .67 but is it the same for this CMB .67?

in my hydro i run at 11" on the dot.. in a cat you should be close maybe a little longer depending on prop.. what pipe?

chris

 

[JPriami]

I'm told its a Macs pipe. Not sure what model. but its not a quiet one. I know that because my ears are still ringing. I just came in from testing it out in the shop. Thanks for the nfo once again.

 

[JPriami]

Can anyone help me with a baseline setting for the LSN & HSN on the carb for this engine? I’m having some trouble trying to get it dialed in.

From reading a few post above I guess I should try turning the LSN way out or just remove it?