Modifying an OB

[Grimracer]

Topfuel

Email me and we can talk.

Grim

 

[topfuel443]

youve got mail.......

Thanks T/F

 

[_laxmasta2039]

james,

i slapped your carb on the engine after the races on sunday, the glow plug burned out quick [not b/c the carb, it was an old plug] but the engine really roared while it ran, it spit fuel out the pipe and stuff but once i get a chance to play with the needle it will probably stay on we put the stock carb on the IB .18, which had a little metal carb which is nicer quality but smaller bore......does anyone know if it's better to use the stock carb while breaking in, or even if it's okay to use a .21 carb on a .18 in the first place? also, is it okay to install a carb slightly twisted to one side?

Joe

 

[topfuel443]

Cool Joe, Let me know if you get it dialed in. I managed to run my carb on my new tunnel this weekend and it seemed to make a big improvement on top end, however I had to run it very rich. But once it clears out it seems to be ok. You can mount the carb in any direction you want, should make a difference. ~ James

 

[_laxmasta2039]

james,

same thing happened to me, i had to run really rich for it to go steady....we're going to be taking the new .18 mono out for it's maiden voyage this weekend, i'll get some running in with the .21 too hopefully. let me know if you get your carb running lean, if i can't get it much leaner than it'll eat up fuel too fast for my tank to run a full heat.

Joe

 

[GTR]

hi Guy's,

when you bore out the carb do you enlarge the spray bar outlet? If you go up to red carb sized venturi you need to open up the hole also or the needle has to be screwed almost right out to get enough fuel in. trying opening it up if it isn't.

GT

 

[topfuel443]

what size should the hole be opened up to? Or just go up the next drill size from where im at now? GTR also we are opening the throat up to gold carb size from the black carb not the red. is there a difference in spray bar size between the black and gold?

 

[GTR]

I don't think the black & gold carb have different size holes in the spray bar. However, if your needle is more than say 2.5 turns out you could go up a few thou to allow more fule at the lower needle position. I thought you had gone to the red carb size where you need to go to a number 53 or 54 (can't remeber for sure) drill.

You can also try opening up the inlet nipple on the carb to allow more fule pressure here, and make a good chamfer on the very opening of it, These littel thingsd help the fuel get in easier.

GT