i just got done with my new motor, and am having some major carb issues.. i have a 351 windsor 10.8 comp with a comp 280 magnum cam,, i have a 3310 holley with secondary metering block. The mixtures screws work sometimes and sometimes they acctually make the engine idle best when fully screwed in,, i put a holley trick kit in the carb.. the manifold vacum is at 6 pounds. so i put in a 4.5 power valve. still mixture screws not always effective. throttle plates are almost closed i can get it to idle way down,, doesnt seem to have a leak. has a bad sputter while trying to get around block after power valve change.. doesnt like throttle. it has been bad enough to need an oil change because of gassy oil. i have talked to holley and did everything they mentioned.. what is the symptoms of a incorrectly adjusted bowl vent.. my secondary threottle shaft has some pleay in it also. i have messed around with jets also... would my 1850 600 be a better choice i put it on tonight to try and it poured so much gas in that i am now hydro locked. i have since adjusted float, but they were set low before this happened,, fuel is just flowing in.. i dont want to ruin my new motor with these problems,, thought about getting an edelbrock, since everyone says they are so easy to work with.

thanks for any help, Dave

 

my advice get a new edelbrock 1406 600 cfm with electric choke. it works great

 

A Holley 3310 is a total mismatch for your engine, you'd be much better off with a 600-650cfm carb, the telling factor is that the idle screws aren't doing their job and they should be.

With that carb you at least need to go over to a 3.5" powervalve, and rejet the carb down quite a bit.

 

I think a 600 would be too small for that compressiona and cam. You seem to be running extremely rich and that is extremely bad for the engine. You may have more than one problem including a vacuum leak, maybe on the manifold to block. I would check float levels and look in the carb while running at idle and make sure you don't see any fuel comming out of vent or venturies.

 

Just a guess with gas in your oil sounds like the float has a hole in it is it a old carb . To check you could remove the floats and sink them in a can of gas over night use a weight to hold them down remove the weight if they sink they have a hole .