holley expert?

[rowingone]

I"m having problems with the adjustment of both float levels in my holley 600 . . seems no matter how far I turn the external adjustment screws in the float level doesnt go down . . my assumption is that the little o rings on the needle and seat arent sealing properly . . so is that the only thing that could cause the non adjustment problem and does anyone know the exact size of these o rings?

 

[WayneC]

First let me ask a couple of dumb questions (I'm not an expert either, it's been awhile since I've rebuilt a Holley)... you are adjusting the large screws on TOP of the Holley fuel bowls (the ones with the lock nut on them), right? And you are allowing the carb a minute to readjust the bowl level with the engine running before you check the level again? If so, then...

I suspect the problem could as easily be the viton-tipped needle as the O-ring. If I recall correctly, I think the whole needle & seat assembly screws out from the top, so you could do that to have a look at the parts.

Holley lists a kit containing the adjusting nut and gasket, locking screw w/gasket, and an O-ring; part number 34-7

They also have needles & seats, but it's not obvious on their website which kit is the right one for you; it's one of these:
6-506
6-508
6-517

Try 1-800-2HOLLEY to determine the right needle & seat assemblies.

You may be able to find the parts at a local speed shop or NAPA, etc.

 

[rowingone]

thanks wayne . . yes I adjusted as you described . . . think I'll try new o rings first and then maybe the needle and seat assembly . . I'm not sure how to tell if the needle is bad . . I cleaned them and the appearance is ok?

 

[WayneC]

Well, I'm not certain if you can tell by looking at the needle, either, assuming nothing looks amiss. I suspect even tiny flaws or alteration of the shape or embedded particles in the viton could cause a leak. Also it might be worth looking down into the bowl through the hole with a light to see if you can tell if the float lever is aligned with the needle center (hasn't come loose and shifted), and maybe poke it to see if the float appears to be floating rather than sunk to the bottom (unlikely, but perhaps possible).

I agree the O-ring is the simplest thing to check first.

Did you rebuild the carb yourself? I ask because the float should be preset at a level adjustment with the needle & seat in place and the bowl upside down, in order to be sure you're in the ballpark before re-installing it and using external adjustments. You might even use a wire or tube to measure down to the float arm and compare that to the needle & seat assembly length to assure yourself that the butt end of the needle actually does contact the arm.... because another possibility, although unlikely, is that the 3 needle & seat assemblies (that I previously mentioned) may be different in overall length and that the wrong ones were used when the carb was rebuilt.