Last sunday I went to the Maverick Dyno day and found that my carb is running lean in the idle-3k range than it gets a little rich after that... here's the kicker, I richened up the Primaries as rich as it'll go (the biggest jet and smallest rod in the tuning kit) and got back on the dyno and it still had the same air/fuel ratio numbers as before ... I was thinking that some junk got through the filter and cloged the primaries, is this a reasonable assumption? Is there anything else I should look at? Yesterday I did a partial cleaning by pulling it appart and spraying everything down on the top half (I didn't remove the carb to clean the bottom but I did spray into the jets with carb cleaner to push anything out) and I removed and cleaned the venturies (primary and secondary) as well as the accelerator pump jet. I also reset my floats... Is there anything else I should do? Thanks. I also redid all my fuel lines from firewall to pump and pump to carb and this time I'm using a stock-type filter instead of that clear one from autozone/checker...
the springs on the metering rods may be too soft. or maybe the metering rods or there pistons are binding and the rod is staying on the cruise circuit. it starts getting better when the vac secondary flap starts opening at the higher rpms.
is there a basis as to which springs to use? i.e. "half of total vacuum at idle"? or something like that? I was temped to take some 2000 grit sand paper to my rods to clean them up but didn't want to risk damaging them.
Id start with a new fuel filter. Ther is an edelbrach tuning kit with multiple combos of rods and jets, it comes in a little plastic tackle box insert with some charts. Ryan had one at Dyno Day with lots of goodies inside.
the springs are color coded. when you buy a spring kit it should come with the vacuum level that will over come the spring tension. i just remembered that float level will effect air fuel ratio. the lower the float in the bowl the leaner the mixture. the higher the float is the richer the mixture. what happens is the weight of the gas on top of the jet increases as the float is higher in the bowl increasing the pressure of the fuel being pushed through the jet. you may want to check the float level and even try raising it past the factory spec. to see if it has the desired effect.
Id ask Ryan the sand box Edelbrock Guru. IMO I would tear it down, clean it, and rebuild it. I was there at dyno day something was not right with your pulls. I cant say it was a carb problem. But something was not right. It could have been a timing adjustment, I dont know. Id start from square one to eliminate every doubt. Bad fuel? Im glad you survived the "Ground Loop" on the way home. I would have taken a bow.
another thing to remember is that the widedband o2 sensors are only measuring the oxygen in the exhaust. if you have a missfire the oxygen doesnt get burnt and the o2 will read that as lean.
I did tear it down but I didn't pull the lower half off the intake but I sprayed all channels that I could with carb cleaner. I only did a base set on the timing no real tuning only set the total to 34. The fuel was pretty old, since I don't drive the car much I have Sta-Bul or what ever it's called in there. On that road, if I got out to take a bow I would have just got run over. Would'nt a missfire be more apparent? plugs and distributor both have low miles and the wires aren't that much older... the plug gap is quight conservative (low side of the mallory gap suggestions)
I would take the carb off the car and tear it down to make sure there isnt anything plugged up. coul be one of the primary jet passage or venturi is plugged up. Take it all apart and spray out every hole and passage. Its a very simple carb to take apart. take each venturi out of carb and spray them out. When tearing it down watch for the little balls hear and there, I think theres one under the acceleraor pump squirter, and somewhere else but Im not picturing it right now. I know Ive taken it apart before and about lost the damn things when they fell out.
