2-bbl on 301 running WAY too lean, but why/how to fix?

[Bonnewagon]

Do as suggested and check everything else first. Then and only then can you be sure the carb is at fault. FWIW the 2 barrel Dual-Jet is the ideal carb for a dead stock 301. The 4 barrel Q-jet was offered but it really was overkill. I found out the hard way that unless you have better rear gears the 2 barrel is about all the 301 can use. Since the Dual-Jet is essentially the front half of a Q-jet, all the Q-jet rebuilding and tuning tips apply. That said, and old float can absorb fuel and sink, flooding the carb. Air bleeds and idle passages clog. Sounds like a rebuild is in order, and will be money well spent.

 

[King_V]

I do plan to keep this as a 2-bbl - since I plan to keep the tame 2.41 gears, and want this as a smooth, relatively economical cruiser, rather than a brute (at which point I'd probably just swap to a 350 or 400). If I can tweak a little extra torque out of it, so much the better.

I think there's only 2 or 3 other vacuum lines that have sizes that are not 5/32" that I have to replace. Hey, I had a spool of 5/32, but I didn't have anything else! They actually look to be in decent shape, but I want to just get all the rubber hoses replaced. One's 3/16, one's 1/4 inch, and whatever the size is of the PCV line, etc. Gotta get those taken care of.

I only did a "quick and dirty" carb base gasket check by simply bearing my weight down on the air-cleaner assembly as the car was running. It made no difference, but I don't think that's exactly a good way to check the carb base gasket! LOL

Now that i know where all the vacuum lines run, I might try disconnecting them ALL, putting vacuum caps on, and seeing what happens. May try that either before or after doing the following:

- Replace remaining odd-sized vacuum lines, and PCV valve
- Fuel pump
- Plugs, wires, cap, rotor (check advance springs while I'm at it!)
- Pray that all the weird vacuum delay valves and thermal vacuum valves still work correctly!

If that doesn't work, then, well, I suppose I have to blame the carb. Dang shame, too, seeing as everything off-idle runs beautifully, and the previous owner said that the idle issues started very abruptly, sometime in the fall of last year (I bought it in December)

 

[Bonnewagon]

Actually, just about every carb problem is usually a dirt/cleaning issue. Once a carb is installed at the factory the only thing that can go wrong is it gets dirty. Few things ever wear out though the float can leak and sink or the inlet needle/seat can wear to the point of leaking. But it's usually just dirt. Buying one of the Rochester books and learning how to rebuild your carb is one of life's better moments.