Re: Lean backfire Holley Street Avenger 870 vs 489 BBC
There is an inherent problem with the 870 Avengers - for some reason, the secondaries dont come it right. Lotta times, its just delayed - you can feel them come in, but its too late and another gear change is coming. I took one to the track, and the car just about stalled and had a slight backfire. Couple friends of mine had teh same issue, and got other carbs. No amount of tuning with nozzles, springs, 50cc pump kits could fit it. All the other vac sec carbs including the 770 Avenger did not exihibit this issue - they run great.
A regular 850 DP will fork great for your 489.
69 CHEVELLE SS
502 EFI/[224/228 HR]/T56/3.90