Idle Surge In Gear

I've searched on here but thought I'd start a new thread to see what everyone's thoughts are for my situation.

This is a BBC 12° head deal, 14-71 HH, setback rotors, four blade hat. It idles stable in natural, but as soon as I put it in gear it surges enough to make staging a challenge. I've tried curing this by adjusting the BV without any success. That being said I do have a fuel distribution issue at idle. Numbers 1-2 are very fat at idle and the rears are hot and lean, so I can't richen the BV any more without causing #2 to go out at idle, if I lean it the rear cylinders will be over 1000° at idle. Not sure if this is causing the surge or not. The throttle blades are at .012 and both stops are contacting solidly, so there is no twist of the shaft. At WOT the fuel distribution is not a problem, the plugs are very even front to rear with very little stagger in the port nozzles.

I only have the blower at 13% OD, but it does make 27# and I don't really have the need or want to run more boost or OD.

 

What RPM are you trying to idle at?
You can try opening up a hole after the blades to help from sucking them closed.
.012 seems a little tight on the blades. What hat are you using?

 

It's a CF JBR four blade.

 

I've had that happen when the valve cover blow off vents get plugged up too. I had a vent at the rear of the car in the puke tank get blocked. Once the slightest bit of meth got to the filter it suffocated the engine at idle.

 

Idle poppet pressure too close to pump pressure at idle opening and closing while in gear?

 

Idle poppet pressure too low. I have mine at 8-11 pounds and the problem vanished.

 

My idle check is at 15#, port at 26#. I do have only one return spring on the right side, not a strong spring though. I'll check that, thanks Will.

 

Mike, are you thinking that the idle check may be opening and closing once I put in gear and the pump speed slows down?

 

In gear it surges between 1600 and 2600. Out of gear 2200ish. This is a powerglide.

 

Sounds to me that your hat nozzles are too big and that is only feeding fuel to the front two nozzles. How any hat nozzles and what nozzle sizes in your hat?

 

Try putting a 30# poppet in the front two nozzles putting the fuel further back in the hat.

 

rich....lean....rich....lean....rich....lean....

 

Have you checked your poppets since the problem started? Every time mine starts surging I find that the idle poppet isn't seating fully. Clean it up and it immediately idles better.

 

I haven't, but I will....

 

What's the "optimal" opening with a 4 blade hat? I have always seen/heard .012 is right around where it should be set

 

Thanks Mike!