Carb Tuning w/ Wideband

[Handy Man]

Howdy,

I'm tuning the Quick Fuel 750 DP on my freshly built 347. After initially setting float levels and idle screws (highest vacuum at 1/2 turn from bottom) my AFR's were:

Idle: 13.5-14.5
Cruze: 12.5-13.5
Light Acceleration: 11-12
Anything over medium acceleration: Maxed out rich (gauge reads as low as 10)

It ran perfectly on the primary circuit, but getting into the secondary side too early caused a bog (not surprising with how rich it was)

So I upped the idle air bleeds by 2 sizes (from 71 to 73) to try to get the idle screws in the 1-2 range, reduced the secondary jets by 3 sizes (from 80 to 77) and reduced the secondary squirter by 2 sizes (from 31 to 25). After re-tuning my idle screws (3/4 turn from bottom now) my AFR's were:

Idle: 13-14
Cruise: 13-13.5
Light Acceleration: 11
Medium to full throttle: 10-11

It still bogs if I get on it hard and fast, but not quite as bad. Still runs great on the primary side.

So what should I try next? I want to get light, medium and hard acceleration all around 13 so I'm thinking I should go with smaller primary jets, and maybe play with the secondary linkage and cam to try to reduce the bog?

[mean buzzen half dozen]

Need to adjust the accelerator pumpshot, but you may also have to replace the pump discharge nozzle to a smaller size.

Try two steps smaller.

Also go smaller on the secondary jets again.

Try the smaller secondary jets first, try it out, if it still bogs, then do the smaller nozzle.

[MonzaRacer]

Don't forget to optimize timing, and make sure vacuum advance is hooked to manifold vacuum .

[4086D9]

My dad is having almost the exact same issues with his QuickFuel 750dp Black Diamond.

mixture screws...3/4 from bottom
Idle...13.5 ish
Part throttle...11.5-12.5
WOT...within a few second would go 10.0 on the gauge

The car had a oval filter with 2" paper element on it. So we pulled it off and used a 14x4 K&N round style next. Guess what...all ratios stayed the same except WOT. Now its right at about 11.8. The filter appeared to be starving the motor for air. The factory jets in it are 74/84's. now going to rejet and maybe try a high speed air bleed change once it gets close.

Also from what I have found play with my buddies 650 Quickfuel DP in order to get a full point change in A/F we needed to remove alot of jet. Im talking 4 primary/4 secondary. Now its perfect!

Idle...14.0
Cruise..14.5
WOT...12.8-13.0