k& B OB head clearance

[J_Moore]

Just wondering guys. Anyone that runs this outboard, what is a good starting point for a head clearance. I'm at 000.6 now and its a new P/S was wanting to break it in for my son as its his boat. Thanks again to Mr. Otto for so generously donating the head botton and cooling jacket for his engine. He's buggin me to get this thing in the water. Thanks

Jeff

 

[SayMikey]

thats a good number

 

[J_Moore]

k thanks Mikey

 

[camaroboy383]

to be clear 000.6" or .006" ??? cause were talkin tenths then thousands...... ive seen plenty down to 6 tenths of a thou... hard to compensate for wear in the rod that close... be careful and always measure it to see if its changing...

 

[RodneyPierce]

Im pretty sure we are talking 6 thou brother, not 6 tenths And if he is running .6, well, thats nearly impossible. Thats over a half inch of clearance.

 

[camaroboy383]

idk rod..... i know guys runnin down into tenths of thousands man.... its crazy,,its like a baby sitting job keeping an eye on that...

 

[Lennard Cuenco]

how are u guys making recommendations without knowing the engine size?

Jack Garcia gave these numbers from his outboard setups:

3.5cc @ .012

7.5cc @ .013-.015

11cc @ .015-.018

 

[camaroboy383]

no recommendations have been given by me sir.....

 

[RodneyPierce]

nor me. Just clarification.

And Alden, the only person I know that runs clearance super tight is Jim Allen. Well, down to .001 anyhow.

But Leonard, I dont agree with that 3.5cc number at all. .012 is a waste.... tighten it up.

 

[camaroboy383]

andy brown runs or has run engines down that tight.. mark sholund also runs his engines down realllllll tight..... i would have to agree that jacks number must have been conservative,..

 

[Andy Brown]

andy brown runs or has run engines down that tight.. mark sholund also runs his engines down realllllll tight..... i would have to agree that jacks number must have been conservative,..

" i would have to agree that jacks number must have been conservative,.."

Jack's numbers are good 40% nitro numbers ( back in the old days when 40% was the most we ever ran). Higher nitro needs more smack! .006" is good for 65% nitro.

 

[camaroboy383]

andy brown runs or has run engines down that tight.. mark sholund also runs his engines down realllllll tight..... i would have to agree that jacks number must have been conservative,..

" i would have to agree that jacks number must have been conservative,.."

Jack's numbers are good 40% nitro numbers ( back in the old days when 40% was the most we ever ran). Higher nitro needs more smack! .006" is good for 65% nitro.

thank you for chiming in andy....always appriciated........

 

[Lennard Cuenco]

nor me. Just clarification.

And Alden, the only person I know that runs clearance super tight is Jim Allen. Well, down to .001 anyhow.

But Leonard, I dont agree with that 3.5cc number at all. .012 is a waste.... tighten it up.

hey rodney,

i never ran 3.5 or 11cc tunnel, my 7.5 tunnel ran mid 50's topping out just over 60 (calibrated radar gun) at jack's suggested clearance, which was decent speed in my district at that time (iUnno how fast peeps are goin these days), i was using andy's props as well

 

[chuck]

.006 hope you have alot of plugs on hand!

 

[RodneyPierce]

With a correct button and needle, you shouldnt NEED to have a lot of plugs on hand....

 

[J_Moore]

Sorry guys yes Rod your correct i meant 6 thou. And its on 3.5 kaboom outboard. Running 50% nitro. Maybe i'll bring it up a couple thou and start there just to be safe. The rod and crank and P/S are all new and running a titanium rod.