[Cliff R]

There are secondary metering rods with long tips smaller than CE, the rods from the 301 turbo carburetors are one example.

Since I build and supply parts for folks who race in quite a few racing classes, including circle track , most carbs are supplied to them with a set of machined secondary metering rods machined from the same cores.

These rods will then have the same upper section diameter, taper, tip length and included angle leading to the tips. This is the ONLY way to make predictable metering changes with a Q-jet without also having to mess with hangers.

Some racers are more meticulous than others and want a full set from about .028" to past .060" in .002-.003" increments. I think .005" is close enough, but if you are trying to be the very best and data logging, using DA, etc I guess precision is king.

The later model Q-jets are 850cfm, not 800 cfm. All early versions are 750cfm. Most don't flow to full potential as the factory limited the open angle of the secondary air flaps and sometimes the secondary throttle plates (1968 FB's come to mind here) to limit CFM and engine power.

I do agree that the biggest stumbling block for the Q-jet is one N/S assembly, but even with that going on we have customers feeding big power with them and running well into the 9's. Several ways to skin that cat. Some use smaller N/S assemblies and high fuel pressure, other larger N/S assemblies and less pressure. ALL will use at least 8AN fuel lines, and a rear mounted pump at 140gpm or larger fed from a sumped tank or fuel cell.

As far as tuning with secondary metering rods your aren't chasing much there, assuming the carb is well dialed in right to start with and staying FULL on a hard run. On quite a few occasions early in my learning curve I've changed secondary metering rods from so rich the engine was huffing a little black smoke to so lean it started to surge slightly on the top end and didn't see more than about a tenth and a half for ET difference and less than 2mph.

So if you thing you're chasing half second or so in vehicle performance save your time/funds. Personally I prefer to run a tad 'fat" at WOT. EGT's are lower and less chance of putting a piston in the oil pan just to show a few hundreds quicker on tthe time slip.....FWIW......