I have a 66 f-100 with a 352 cu in engine and two barrel carb. I am wondering if there is a better degree to adjust the timing to instead of 10 degrees before top center. when i say better i mean best all around power band from 500 RPM's to 4000 RPM's. My truck seems to lag around 1000 then picks up at 1100. I am not sure if it is in time now but my service manual says 10 degrees before top center is in time. should i time it to 10 degrees when i time it or should i time it to somthing better? Also how do i adjust the carburator? Where are the jets (which is air which is gas) and is there a tool that can help me adjust them procicely? I just got a glass pack put on and when i step on the gas a puff of strong gas smelling smoke comes out so i think i am burning rich.

 

I'm sure no expert. But have been researching the same questions for my 1966 F100lwb. I initially adjusted the timing according to specs and still had poor performance at higher speeds. I advanced to about 12 degrees BTDC and changed ignition coil and distributor cap (had already changed wires, plugs, etc...next to change rotor, condenser) and greatly improved performance. From what I read on these forums, a lot of the guys like to advance the ignition and heat up the spark. Still think I'm running a little cold.

I was just about ready to tear down carb thinking problem was with fuel supply. I had adjusted the carb (Autolite 1 barrel) by vacuum gauge and found the engine to perform very well when monitoring vacuum. So I ruled out problems with fuel and stayed with troubleshooting my ignition. I'd say that $10 vacuum gauge was money well spent. Now, I will always adjust my carb by vacuum! Still want to change out that carb and maybe the intake and exhaust systems, but that mod can now wait.

 

I imagine my 65 has the same 2bbl. The air/idle screws are under the float bowl facing forward where you can't see 'em too good, but they're there. Normal settings on just about all carbs are a turn and a half out to start with and go a turn or so from there. Adjusting them is normally an "ear" type of deal, listen for a sweet spot more or less, but you could hook up an intake vacuum gauge and adjust for the highest vacuum point. Might help.

Be aware the screws have a brass tapered needle on the other end that is easily damaged. Don't crank 'em down hard to find the bottom point because you can damage the taper. You might as well haul 'em out and make sure they aren't damaged now for that matter.

The black puff when you stomp it is probably something to do with the accel pump circuit. That's located right on the front of the float bowl. On my truck the linkage to the pump can be installed in 2 different holes that affect the "throw" of the pump and therefore how the gas gets pumped. You'll see it.

Mine happens to be in the closer to the pump of the 2 holes which would be the max setting. You might check yours and if it's not already there try the outside hole.

Another possibility is a leak at the squirter. With the motor off look down your carb while jacking the throttle and watch what happens. You should see a squirt of fuel out of the nozzle of the squirter with even the slightest movement of the throttle. If it's leaking out somewhere .......

The main jets are located inside the by now famous float bowl. but I wouldn't go in there. You've got a tuning issue. A main jet change would only be needed if you did some kinda major mod to the motor.

As far as ignition timing I can't help much because mine runs so sweet I've never fooled with it. I love the way these old trucks start. Just a bump with the starter.