Well I'd like to say its better news -


Just to recap, here's how the carb behaved on the DP intake before the swap -

Mixture screws 4 turns out
AF - idle was 12.2, Cruise was 14.5 and WOT was 12.5
Vac was 13
Jets were .101 / .138

I had it running pretty darn good.

On Sunday after the swap - I had

Mixture screws all the way out
13- 16 AFs bouncing around like crazy at idle
Off the scale lean at cruise
Vac bouncing between 9-13 and dropping to zero on deceleration.

I swapped on a buddies AVS 650 and all the bad symptoms went away!

- it idled at 12.5 and I had steady Vac at 15.

This told me it was def a carb issue - not an intake leak.

- so here's how I spent my Tuesday evening -

Testing of TQ,

Replaced the carb flange gasket - improved slightly but still a vacuum variation and running pretty ordinary (Sorry its bad news Dave) - AF was between 13 and 14.5 at idle

Took the holes in the butterflies out to .094th - slightly more even idle but a still way lean and a big Vac drop after blipping the throttle.

Blocked off the air bleeds completely, and the idle settled - it stayed around 12-13 AF and the Vac settled at 14.

So.......I thought I had it licked - till I went for a drive , and -

AF dropped to zero when i let off the pedal

AF went to 9s under light acceleration and I blew black smoke.

Conclusions

- Blocking the air bleeds richened the mixture so it idled better

- but the low speed circuit needs the air from the bleeds to maintain a decent cruise/light accelration mixture

In which case - blocking the bleeds is not going to work.

Next step

Would I be right in thinking its not getting enough fuel through the idle circuit?

Is this common?

In which case, how do I fix it?