Hello all, is anyone familier with the CMB .67 nitro engine with dual plugs? I need info please, I am thinking of buying a rigger boat that has this engine installed in it.

No personal experience but have seen a few of them run. I'll try to give you a little help as that's about all that I can offer.
Since I really don't know right now what you need to know, I'll throw this out to you.
Nitro is a slow-burning fuel so CMB added the second glow plug so that higher nitro can be used in it. When starting you just fire it up with one ignitor then once it's started you hit the second plug briefly to get it glowing. The nice thing is that if one plug fries the other might get it back to shore.

Thanks. I am looking at a used rigger boat which has this engine, it is about 36" x 18" looks like a fast boat to me, just do not know much about the twin plug heads. I am figuring it needs at least 30 - 40% nitro fuel to boogie out

Yeah, that baby ought to scoot! 40-60% would work in that engine as the twin plugs will allow you to use higher nitro. You just don't see those engines around much any more but I've seen twin plug engines as small as .45's using them. CMB must have seen some kind of performance gain for them to use that head but how much, I don't know. It sure seems to work in fuel drag cars though.

Iv got about 25 dual plug buttons right now, The idea as I know it was to give a "even" burn to your fuel, in a .67 make sure you have the correct head button bowl for high nitro, as most will detonate the head button and piston to death with 50%+ fuels. My advice would be send it to a CMB engine guy, and have it blueprinted.

40% is what i run in my sport boats, 50% and higher for the 21's, and 25% with 18% oil for my .90~101 motors.

The dual plugs are waste of money.You only need one!I ran one years ago first thing i did was have Steve Woods make a single plug head button.The second thing you need to have the disk clearance set.Those are bullit engines but are harder to work on.

How do you know its a evo motor Roxy?? If its a HR/Green head, ect it has a drum..

Here is the ebay auction I am looking at, nice boat but I think it may be a bit much beast to tame


190243859051 ebay auction number

Yep... Evo, I'm building 2 right now for Crazycat.


I cant say if i would buy that boat.. The motor is old, And I'm about 99% sure I bought the last 5 crankshafts in America last month. So... If you were to buy it, once the motor is wore out, toss it in the trash and go buy a modern engine.

thanks guys for the input, the boat sold and I did not bid on it.