Tuning With AFR

[kfa670]

Carb is a 17058204, and is set up after a rebuild pretty close to Recipe #1. 

Idle Tubes: .036
Idle Channel: .046
Lower Idle Air: .072
Upper Idle Air (Main Cast): .065

All MABs: Pressed in .070s From Cliff

Mains Jets: .071
Primary Metering Rods: Cliffs Tapered rods (.044?)
APT: 4 Turns from bottom

Secondary hanger: O
Secondary Rods: CZ
Secondary flap Spring: 3/4 turn

Float at 1/4"

This sits atop a mild 350 (RV cam, Performer Intake, Headers) inside a 89' Landcruiser. Timing at about 16 degrees Initial. All in 36 by 2800 RPM.  My vac at idle with the Vac advance hooked up (adding about 12 degrees) is around 14 inches (I live at about 6000')

All in all I am pretty happy with the idle and off idle response.  The acceleration from a stop is acceptable considering its not a race car. 

I am having trouble with a couple different areas...

First, I get a really flooded hot start sometimes... Maybe every 3rd start after 10 or 15 minutes.  I have my well plugs welded shut a while back and that helped tremendously in a number of areas of tuning (tried plugging them unsuccessfully), but I still have to hold the throttle wide open and get a lot of black smoke sometimes.  It just doesn't seem to have a very crisp start anymore.  My float used to be lower than 1/4", and I'm wondering if I should put it back? like 3/8?

Second is I'm having trouble with WOT.  A question I had is... With the Secondary flaps locked out, can the secondary fuel circuit still add fuel at WOT?  I have always read that you should tune the primary side first by locking out the secondaries and taking some WOT runs. I locked mine out and noticed a difference in "response and noise" but my AFR readings didn't change much. I originally had CH Rods, significantly fatter tips than the CZ's.  My WOT was rich at 9s to 10s. So I tried an experiment (sort of by accident).  I removed the little screw holding the hanger on.  With the secondary flaps again locked out, WOT leaned the carb out to the point of killing the engine.  AFR was showing total fuel starvation.

I'm a little uncertain where to turn next.  I am now running the setup at the beginning of the post.  With the fatter CZ rods, my AFR's at WOT have definitely improved but it seems like they should be leaner still.  I am now around 11s to 12s on a WOT run.  I hate to go down on the primary jets any more, because I tried .070s, and my cruise and midrange start to suffer.  I end up having the APT screw turned out like 6 turns to keep from running in the 15-16 range on the AFR.  How high is "too high" for a APT screw?

Thanks for any help and suggestions.  It is very drive able the way it is now but I just feel like there is some performance missing

[77cruiser]

With just the air valve locked it would still pull fuel, but if you lock the secondary plate shut it wont.
15-16 in the cruiser range is perfect if it doesn't surge or misfire. If you can get it around 13 under heavy acceleration with out opening the secondaries you should be good.

[boogie]

I have the same carb number on a 383 sbc. I have my float set at 3/8", APT 3 turns up from bottom, and Cliffs 77 jets along with the 44 rods.  It works great!

[kfa670]

Thanks for the reply guys. Haven't had much chance to tune lately as I was working on my truck.

Have to do a little more testing. Definitely going to move my float back down a little as now it seems like I get a few fat starts, more than before anyway.

Boogie what elevation are you at?