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Dual HIF6s on a B20E. Forward carb was rebuilt using kit SU23. The rear carb has not been rebuilt, but I am awaiting the rear rebuild kit (SU23R) in the mail. Both carbs use BAL needles (emission needles). Both carbs have tight throttle shafts and new throttle shaft seals. I don't trust my ears as much as Ron Kwas so I use a carb-balancer tool to synch the carbs, my tach to check idle speed, and the piston lift-pins to check air-fuel mixture.
My timing is set to the spec 10 BTDC @ 900RPM. Lifters have been gapped and re-gaped to spec.
So here's the weirdness. I set my idle down to about 900-1000 rpms, as lean as possible and balance the airflow to the two carbs. When trying to get the A/F mix to proper, the front carb is all but irrelevant - that is, the lift pin does not cause any change in idle at all in #1, and the lift pin on #2 immediately kills the motor. It took me a bit to realize that when synched and mixed the same the rear carburator is dominating the setup - although the front carb has the choke.
This has resulted in some very poor performance in the car since I got the whole thing back together. It has taken significant time and driving distance before the car ceased to "buck." Even after 25 minutes of my 30 minute commute, the carb acts as though they've just been started up. Dangerously, the car would have no power at all starting from a traffic light and would often lose power midway through acceleration. Strangely, the car does not exhibit any of these symptoms in the afternoon return trip.
Sooo... after spending some more time on the carbs this evening and adjusting the linkages to further synchronize throttle response, I found that dropping the air-flow on the rear carb to about 1/3 allowed the throttle behavior to "act" more like the carbs are in synch - even though they are not. The lift pins individually slowed the idle about the same and neither killed the engine.
I figure that when I rebuild the rear carb, the overall behavior will improve and may "balance" properly, but just in case something else is going on, I wanted to ask for ideas on other possible issues here.
I previously tried richening the A-F mixture but all that got me so far is a fast-dropping gauge gauge.
Any thoughts?
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