Whiteknuckle

mcrsr,
The metering rods are available at GM Dealerships or you can purchase them from Edelbrock for the q-jet. Dennis Moore's book on Big Block Chevy Marine Performance has a list of all the secondary metering rod sizes. They are easy to change, in fact you can do it with the boat running if you want.

Good luck with what ever you decide to do, but do not run you engines to lean. It is better to have a little bit of soot to clean up off the transom once in a while than to run to lean.

Mkeller

Don't give up on your Quadrajet. The quadrajet was Dennis Moore's carb of choice in his book for all around best performance. I have twin stock 454's with quadrajets on a Formula 330 ss. Great idle, no stumble anywhere, planes instantaneously and hits 55 on a good day (remember this is a heavy broad beam boat). And seems to get significantly better mpg than the same boat as tested by boating with spreadbore Weber carbs. I don't burn but 3/4 the gas I expected to (but then the wife won't let me go out on the boat half as much as I want)

I have a real world comparison between the Holley 6150 and Quadrajet. I recently switched the carb on the stock 401 in my '65 buick wildcat from a Holley squarebore to a quadrajet and saw a huge difference in upper RPM performance, a much smoother idle and a 50% increase in mpg in normal driving (from 8 to 12 all city driving). (the holley was untunable for a good idle on this engine) This was my first new carb tuning experience and I spent more than my share of time throwing tools around the yard in frustration while getting rid of the infamous bog. Once tuned, I couldn't be happier. Seat of the pants suggests a 30-40hp gain. Unless I was looking for all out top end performance I wouldn't have another carb on my GM engine.