CMB 67 Pipe Length

[John Seybold]

Hi, I have a CMB 67 Greenie and am wondering what length I should start at with the pipe. Its going in a scale boat and I'm using a CMB black muffled pipe with an AccuTech header. I measure from the glow plug to widest part of pipe correct? Do I remove material from the header or pipe?

Thanks

 

[Michael Costanzo]

depending on the boats weight and prop,i woulds start at 11-3/4" and go from there.as far as cutting header or pipe,i try to keep the pipe the same length and go to the header first.PS, i have done it both ways with not too much of a difference.good luck. mike.

 

[jwo]

Lke Mike said. It largely depends on wieght and prop. I run mine at 11 7/8 with a 15 lbs boat and run a 255 most of the time. I also have been using the Accutech header. Be aware that this header has very thin lip around the holes for the spring. I have had 2 of them pull through in a couple runs.

Anyone have a steel ring that will fit it to eliminate the problem?

John

 

[Bert Dygert]

John,

I'm at 11 3/4 inches. Measure for the center of the bore on the case where the CMB 67 is engraved into the block running center on the pipe to the weld. Start with a X457 three blade for the two wing hulls. Your flow should be around 0.90 on the flow mtere for the two tank system. Both your hulls should weight around 14 lbs dry ( less fuel). Make sure your head clearance is around 0.013 - 0.015.

Bert

 

[John Seybold]

Thanks everyone, John did you contact AccuTech about the header problem? I wonder if James knows theres a problem with them, I'll keep a close one on mine.

 

[SayMikey]

Lke Mike said. It largely depends on wieght and prop. I run mine at 11 7/8 with a 15 lbs boat and run a 255 most of the time. I also have been using the Accutech header. Be aware that this header has very thin lip around the holes for the spring. I have had 2 of them pull through in a couple runs.

Anyone have a steel ring that will fit it to eliminate the problem?

John

John Rossi used to make a ring and spring assembly should be easy to duplicate... I have one pm me your email if you want a pic

 

[Mike Cathey]

Lke Mike said. It largely depends on wieght and prop. I run mine at 11 7/8 with a 15 lbs boat and run a 255 most of the time. I also have been using the Accutech header. Be aware that this header has very thin lip around the holes for the spring. I have had 2 of them pull through in a couple runs.

Anyone have a steel ring that will fit it to eliminate the problem?

John

John see if you can get Lee Robertson to make you one of his stainless ones. Nothing better.

 

[m brater]

I'm sport running with 20% and after 4 tanks of fuel (from break-in) I blew both plugs when I finally went to WOT on my cmb cam 67.Bud T-5. Using a x450/3. Going to try a 447/3. I've since switched over to single plug head. What pipe length should I try w/ 20% and 447/3? How much fuel do I need to run before I start to shorten Pipe? Thanks MIke