16 replies to this topic

[dklawson]

Turns out there's a pretty substantial groove on mine.  

 

That's the witness mark I mentioned in post #7 above.  The grooves that wear into the tip of the float valve can indeed let extra fuel into the float bowl (particularly at idle) which can make tuning difficult to impossible and the leakage creates a rich mixture.

 

If your friend is letting you keep the needle and seat that he had, great.  If it was just a loan, buy yourself a float valve that has the Viton tip instead of the brass tip.  All needle valves wear out over time but the Viton ones seem to provide a better seal longer.

[dansnyderECE2010]

Gotcha, I'm gonna swap put my oil for something heavier (25W or something).

 

Slapped the needle valve in and now the engine seems to purr decently at 750rpm after a bit of warming up.  Gotta check on the plugs to see if they're still fouling but so far so good!  This valve has a black tip so I assume it is brass coated with something.  I didn't see a huge selection out there so perhaps this is what you're referring to Doug.  Only other needle valve I saw was the mini spares "SUPERFLOW" valve.

 

When tuning your carb, I see that there are at least 4 adjustments that can be made for fuel/air mixture.  The jet screw, the throttle linkage screw that rides the idle linkage, the float needle valve depth, and the jet needle oil weight.  Seems like the linkage and jet adjustments are a function of the float height so I would zero this to some value and THEN do my adjustment.  Jet needle oil weight is more of a matter of acceleration.  It sounds like some people adjust their float height as a last adjustment.  Where should I begin?  I assume that I should probably tune the thing to be a bit lean at low speeds so I can have a proper mixture at 30-40mph (squared relationship between gas pulled through the carb and car "speed" right?)

Edited by dansnyderECE2010, 25 February 2014 - 07:58 AM.