I need some help I just rebuilt a holley 4160 1850-3. I made sure to clean all the passages and retorqued everything to specs. I bolt the carb to the engine it started right up. I set the float level to the buttom of the threads. the engine pulls 24 lbs of vacume at idle. The problem is the curb idle adjusting screw is all the way out and wont it below 800 in park about 650 in gear. I know this about right but the screw has no more adjustment It idles smoth as silk an revs good in neutral. When driving it under light load it will stumble and fall on its face then pick back up and run better. on a hill it seems to serge. Full throttle seems to pull strong with no surging This is my first time rebuilding a holley so am looking for some help from the experts. I bought a holley book and followed the tear down an rebuild intructions. I set the floats per the book and rechecked with the engine running. The mixture screws were turned in all the way and backed out 1.5 turns per the book. I let them at the 1.5 turns because the vacume reading seems very good. Any Ideas?
Hmmm.... There is something wrong with the idle circuit.... you should be able to kill the engine by just adjusting the idle/fuel screws... if it does not affect it , there is some thing wrong.... sounds like you need to look at the adjustments of the accellerator pump....surging is a symptom of running lean.... stumbling is a symptom of a short shot of the accellerator pump....or ,or, the vacume secondaries opening too soon.... did you change the rating of the power valve????? Well, a holley is a modular carb... so start with each system and get it right ... and it will all work together.... Call the holley tech line and they will be able to walk you thru the situation and get is straight.....but.... I am saying if you cannot kill the engine with the idle screws or the adjusting them does not affect the way the engine idles , there is something wrong ....either the carb is way out of adjustment, or you have a vacume leak somewhere else , not in the carb...unless you left a screw out of the carb where it can pull air into the intake without going thru the idle system....
second thought: be sure of the fact that you dont have a vacume leak somewhere else.... isolate everything that can leak vacume,,, The idle circuit.... the idle circuit affects the idle transfer slots and there are air bleeds into the emulshion passages , are they open??? how did you clean the inside of the carb? and did you blow the passages out with compressed air???? When you turn the idle screw adjustments it should affect the way the engine idles to the point that the engine will die..... each one.....if it does not , there is something wrong.... they adjust the fuel/air amount not the ratio... holleys tend to idle rich,,, the only way to adjust the idle fuel/air ratio is to very, very carefully open the air bleeds up to lean the mixture....
You might want to check the rear throttle blades to see if they're opened up too much. They have an adjustment like the front idle screw There is a set screw that is accessed fron under the baseplate from the right side. Adjusting them down will give you more adjustment in the front.
Thanks guys I will look for a vacume leak that was my suspision to. I took the carb apart baging all assemblies together then soaked metering blocks bowls anb body in carb cleaner then cleaned all services of gasket materal and blew out all passage ways I am going to reset the metering screws with the car running this time per the book turn metering screws in till the idle drops then back out to achieve highest vacume reading correct? Thanks much for your help guys
