Carb or ignition ?
Its eating fuel and hurting my eyes .
Classic too much Transfer-slot exposure, usually because of lack of bypass air.
Try this;
Reset your T-slot exposure to a lil taller than wide. Reset your mixture screws to 2.5t on a Carter type carb. Make sure your fuel-level is correct and stable. Make sure your V-can is plumbed to the Spark-port. Make sure your PCV is NEW and correctly plumbed to the front of the carb and below the plates. Make sure the Secondaries are closed up tight but not sticking. Make sure the Brake booster is not sucking air and that the suction hose goes to the PLENUM, not one single runner.
Finally start it up, and DO NOT TOUCH THE SPEED SCREW. Set the idle-speed with Idle-timing. I suggest 12 to 14 degrees.
That is your baseline for the 221 cam.
Now;
if the rpm is too slow at 12/14+ timing;
She will want some bypass air. To find out how much; I tee into the PCV line with a smaller line. Sometimes I install a wooden dowel, plug into the end of this line, and drill the plug out until I get the rpm where I want it AND, very importantly; the exhaust no longer burns my eyes,lol. hen I calculate the area of that hole, divide it in two, and then drill the primary plates to nearest smaller size, one in each . I install the holes on the PCV side, about half way to the edge and between the two ports of Transfers and Idle discharge.
Warning; if your fuel level is not right, don't make trouble by drilling the holes too big. But if you do, don't panic. I have dropped solder into too-big chamferred holes, and peened it into there then dressed the high-centers down. and Finally just moved over a bit.
If the idle-rpm is too high at 12/14 Idle-timing, with the T-slot exposure set right; Something is Wrong! You probably have a vacuum leak. Be sure to check the crankcase for vacuum after flipping out the PCV and sealing the covers. If you have cut the decks it is easily possible for the engine to pull air from the crankcase atb the intake to head interface.
That's the best I got.
Killer low-speed cam that 221 will be.
IMO forget trying to target the idle AFR. Find out at what rpm in neutral, that your V-can comes on line, and work from there.
BTW-1
I ran a Hughes 223/230/110 cam for 4 years; What a great hi-torque cam.But I had to modify the V-can to bring in 22* to satisfy her craving for cruise-timing, with alloy heads. My Idle-timing is just 12/14 with a manual transmission.
BTW-2
If you want a great coil, I highly recommend the Accell big yellow square top, and it's matching ballast resistor. Mine was new in 1999. It does a great job to past 7000, yet doesn't burn up the plugs. My plugs were refreshed in 2004,lol. I mounted mine horizontally on the apron with the terminals down.
BTW-3
the jumping around AFR is probably misfires, or the O2 sensor seeing an up-stream air-leak into the exhaust system.
OOPs Sorry Mattax, I didn't read to the end.
OP, Mattax has you covered
