Pipe length on a .45 HR CMB with a Cooper pipe??

[Sean Bowf]

Pretty sure I asked this before...and I have read some other posts about pipe length...

As I recall (will go see if I can find it as soon as I post this)...I have read everything from 9.5 to 10.5 inches for pipe length for a .45 HR CMB with a cooper pipe.

Attached is a pic of the pipe laying next to the engine, with a length of 10.5 inches from the center of the engine (glow plug) to the weld on the fat part of the pipe.

To me...it looks like I won't have much of a header left, and not much of the pipe left to make it any shorter, if I chose to try it shorter.

Am I remembering the length wrong?? Is there something else I am missing?? or do I just need to quit over thinking it and just cut the dang thing??

Thanks once again for your help,

Sean

 

[Dan_Cousin]

Don't measure to the weld. Measure to where the divergent cone ends. (just before the straight section).

On the old nitro pipes this is where the WELD was. New pipes are different.

Cut the header and not the pipe. The pipe is designed for a particular flow and the header is not. A more practical reason is that headers are cheaper than pipes if you mess up.

 

[Sean Bowf]

Don't measure to the weld. Measure to where the divergent cone ends. (just before the straight section).
On the old nitro pipes this is where the WELD was. New pipes are different.

Cut the header and not the pipe. The pipe is designed for a particular flow and the header is not. A more practical reason is that headers are cheaper than pipes if you mess up.

99% sure I got ya...but just in case...does the attached pic show the correct places to measure from??

Thanks again,

Sean

 

[John Knight]

Drop your measurement line along side of the engine, centered in the cylinder, along the header to the pipe. That is where the flow is and is more accurate than measuring along the top of the engine.

 

[Buckshot]

Drop your measurement line along side of the engine, centered in the cylinder, along the header to the pipe. That is where the flow is and is more accurate than measuring along the top of the engine.

John is correct.

Measure from the center of the "M" in CMB on the side of the case to the weld or divergent/convergent cone.

That pipe looks like someone welded on an extension to the neck of the pipe. I'm not familure with Cooper’s older pipes.

-Buck-

 

[Dan_Cousin]

Don't measure to the weld. Measure to where the divergent cone ends. (just before the straight section).
On the old nitro pipes this is where the WELD was. New pipes are different.

Cut the header and not the pipe. The pipe is designed for a particular flow and the header is not. A more practical reason is that headers are cheaper than pipes if you mess up.

99% sure I got ya...but just in case...does the attached pic show the correct places to measure from??

Thanks again,

Sean

Thats right. Like other say I measure from M on the CMB to the end of the divergent cone. Doesn't matter too much since this is only a starting point. you'll go in or out from there and the action of the boat will tell you if you too short or too long.

 

[RCUK John]

Pretty sure I asked this before...and I have read some other posts about pipe length.

Go back to http://www.intlwaters.com/index.php?showto...mp;hl=rcuk+john

and see http://www.nimrifmodels.co.uk/setup.html