okay

i rebuilt my holley 4160 600cfm carb on my 84 z28 (auto)
runs great for the most part idles better than with the edelbrock.
any ways the only problme i have is at light throttle from like 10 percent open to 25( or until the powervalve opens?) it runs really lean according to my a/f gauge and is accompaied by a hesitation, i tried to change the position of the squirter cam by putting it in position 2, better but still there, by the way the cam is pink. i read that small block chevy usaully like blue ones so i will try that but this lean spot is not just momentary if you leave your foot in that position it stays lean( like cruising at certain speeds)
will a jet size change this. it is slightly rich above and below this point and i wiould like it to cuise a little lean but not off the gauge lean like it is now. any help would be appreciated, thanks

 

was it doing this lean surge before you rebuilt the carb?
what jets are in the carb? what intake manifold are you using?

 

well the carb was not used for a year but from what i can remeber no it didn't, i dont remember what the jets were but im using a holley street dominator manifold the high rise dual plane one. it runs flawlessly at every other point except that cruise sustaining throttle posotion also what pressure should i run the fuel pressure at . thanks, could it be the power valve ?

 

You should run at 5-7 psi. The 600 Holley's usually come with #66 primary jets. At least both the 600 Vacuum and 600 DP I have both did.

 

When you rebuilt it, did you use a Holley kit?
When you move the pump cam positions, recheck the lever clearance (overtravel) at wide open throttle position.

 

Check for a vacuum leak.

 

i used a holley kit.it was very easy except that the gasket s wer like the originals and so seperating the metering block and stuff from the main body was not easy ., Appriximatly when deos the idle system cease to meter fuel and transitions to the primary metering system, couldit be that the primary system is the lean part and the idle system is prviding adequate fuel below that 10% throttle, and goes lean while only using the primary system then when i give it more gas lets say 40% throttle it then transitions to power valve or enrichment mode? does that sound like a correct hypothosis? all this is taking place prior to the vacuum secondaries operating. could that be or is my understanding of holley carbs mistaken.

 

No you've pretty well got it right. Check it over for a vacuum leak then try richer jetting.