Hiya,

On the dyno the operator suggested more crank timing and setting the accelerator pump on the furthest adjustment hole possible which I did. On paper it looked fine unless it's just deteriorated. I remember with the Holley that I had to get 2 sizes up on the primary squirter and an aggressive pump cam. I was just shy of getting a Reo pump for it. For the Elelbrock I don't think one can do much with the pump short of what i did with the hole adjustment. Other than rebuild the thing.
I still have the Holley but the last time I used it it worked perfectly without leaking but lacked any kind of power, A pinto was faster. I just got sick of constantly jacking with it.
I must add that this popping is only under load. You can rap the engine all day and it won't pop at all. Light throttle is fine. Midrange power is superb. WOT stalls, No pop but stalls. 34 throttle under load will pop especially when cold.
Fuel is regulated at 6.5 PSI. I was told the Elelbrock is fussy about fuel pressure but I cranked it up to feel the nitrous gas solenoid cause i think it does run lean when applied. I was told 5.5 is max pressure for the Elelbrock 1401.
The plugs are reading a tan color on the electrode porcelain. They're Bosch plugs rated cold for the nitrous.
The manifold is a Weiand dual plane with the heat transfer passage blocked off at the gaskets.
Only other thing I can say is the engine is capable of 6500 RPM sustainable. Which only adds to my confusion.
Incidentally, 236 HP on the dyno was disappointing to hear. Especially after all the work I did on it. But the power curves and mixture checked out fine.
Well, i'm gonna be working on it this next few days so i can appreciate and new ideas. I'm checking everything again.