What size fuel injectors?

I have found all kind of calculations to figure injector sizes. The problem I have is I am not for sure on the horsepower of my engine. What I have in my sig. is what I have in the motor so far. I have the chance to buy some 42# injectors and I want to make sure they will be big enough. Any help would be appreciated.

42# injectors should be fine. You can have a bigger than needed injector size and still have it tuned to run great, but you can't have too little of an injector as the duty cycle will eventually max out and force you to run lean.

Back when I had a N/A 383 and a cam and ported heads I was running 36# SVO's and they still had room left in them, so your 42#ers ought to be fine.

To look at it another way, assuming no more than an 85% duty cycle, and a decent tune (0.476 #/HR/HP BSFC) a 42#/HR injector can support 600 flywheel HP on an NA engine. Should be OK.

Would I be better off with 48 or 50 lb. injectors?

Would I be better off with 48 or 50 lb. injectors?

42# injectors will adequatly fit your needs. There should be no need to go with a 48 or 50 lb injector size.

Would I be better off with 48 or 50 lb. injectors?

Only if you expect to be in the range of 685 - 715HP on motor.