[Jay S]

It is great that the head is fixed, disappointing that KRE didn’t make that right. But it should at least have some tuning potential now. Look at fuel and timing timing first. As I said earlier, a holley 600vac out of the box is ok on a 300ish HP engine, or even a 250 hp completely stock 350 with an anemic stock cam and a 4bbl intake. A 600 vac is not friendly to tune compared to other Holley’s, it has a jet plate on the secondaries. Before you give up on the 350, try a better carb. A 400 with that carb will have problems making much power also. There is no mention of where timing is set at, but more timing won’t help much when the fuel curve is already very lean. You would have much better results switching the carb to a qjet or a Edelbrock 750 AVS2, or a tuned 750 double pumper.