Gasoline Fuel Injectors: No. of Nozzles Per Injector?

To better your fuel economy advance your cam timing 6-8 degrees, maybe more. You will get more bottom end and this is where most of your driving takes place. Modern VCT engines advance and retard as much as 30 degrees.

Supposedly, these symptoms are an indicator that the injectors are leaking and need replacement.
You should check to see if the injectors are really leaking - they can be tested. Hard starting and poor gas mileage have many causes. No point it replacing stuff willy nilly without knowing what the problem really is.
Is the engine operating in closed loop as soon as it warms up? If it is, and if you are not getting error codes, then the mixture is correct, and injectors are not the problem.

Why should I test? My friend had a neighbor with the same exact color truck, and his mechanic said he needed new injectors every month.

Well, I guess I'm an idiot. My twin cam 454 is such a rare beast that I have variable cam timing and have all the equipment to test injectors. It should be getting 45 mpg because it has a supressed Pogue carb and only phony fuel injectors.

The injectors were already replaced once under warranty by the dealer (years ago) and eliminated the same symptoms.

I'm far enough in the sticks that I can't pull the injectors and find someone who has a test bench to see if they leak or are balanced.

Its cheaper to install a set of rebuilt injectors at between 100-200$. I do my work so the cost is for parts only.

Lots of armchair critics but no answers for my original question: 4 or 6 nozzles and rebuilt VS new?

Jon.

Lots of armchair critics but no answers for my original question: 4 or 6 nozzles and rebuilt VS new?

I think the first post offered answers.

In general, multiple holes offer better atomization. However, the difference between 4 and 6 is small enough that the differences in manufacturing can balance out the potential for better atomization: a good 4 hole injector is better than a bad 6 hole injector. I doubt that, even given the same manufacturer for both, the difference in performance (fuel efficiency or power) would be close to 1% (to small to measure on even a very good dyno).

The pintle and pintle stop are both subject to wear, and neither is replaced in a rebuild. Wear in each shows up as slight variation in fuel flow. Personally, I'd rebuild them myself, and see if the problem is cured. If I were going to buy rebuilt units, I'd want some assurance that the set was well-balanced. (You could end up with one injector with 300,000 miles on the pintle, and another with 30,000 -- and they are unlikely to flow the same.)

Injectors are designed for 1 billion cycles, which is about 1,000,000 miles at 60 mph, so if the rebuilt ones are anything less than 1/2 the cost of new, I'd go with the rebuilds -- just be sure you have confidence in the rebuilder.

Nice injector tech memo to have a look at here.

If you had to have higher delivery rate injectors then more holes would do it for you without having to alter the dwell duration on the ECU map.

Unless the 6 holes are smaller....

Try them out and let us know what you think.