Even though Pony carbs set it up on a test mule, it needs screw adjustment immediately. Float level and many settings must be maintained on all engines, but the idle mixture screw is the adjustment that allows a carb to work from engine to engine. Every engine needs its own special adjustment. You should do this before you go much farther, unless it runs so bad you know it has a huge vacuum leak.
First get you screwdriver and spin the screws in slowly and count each turn to the nearest 1/4 of a turn. Tighten very gently against the seat to stop. Find out how many turns out they are. You will not hurt a thing.
Once reset, start the engine and drive it to get it fully at op temperature. Now with it idling in park, adjust the linkage/throttle stop screw to a 500 to 600 RPM if the engine will hold it. I assume you have a basically stock engine. If it will not idle at 500 or 600 get it as slow as possible. Now go to the air screws. Seat of the pants listening works very well. Turn one out 1/2 a turn. Does it run faster? If it does leave it. Try the other screw. Turn it out 1/2 turn. If it runs even faster, great. Your goal is to get the fastest smoothest idle in this manner. But between each try you need to adjust the throttle/linkage screw out to slow it down to around 600. If the throttle plates are open too much, the idle screws are not positioned correctly on the transfer slot in the throttle plate. So you are wasting your time. That is why the engine must be fully warmed up with the choke fully open. They may need to go in vice out. If your first try out makes it run like crap, go back to the original and try a 1/2 turn in. You will find a point that either a half turn in or out seems to make no difference in RPM. Split it and call it good. Also, one screw may be set a bit more in or out than the other. This is normal.
Do not be afraid of your idle mixture screws! The only harm you can do is to tighten them to tight and ruin the seats or not have any idea how many turns they are out when close. You may solve a bunch of your problems with a simple turn or two.
Tell me about the low speed hesitation. That may be another story.
Rob
Hi Rob,
I'm getting there. Big difference so far.
I was thinking that something was wrong with the timinig, that's why I wasn't playing with the fuel mixture screws. So I went ahead as you suggested with the 2 fuel mixture screws (2 barrels). What a difference.
I ended up unscrewing the left screw (pass side) 1.5 turn and right screw (driver side) .5 turn. It is pretty good with that. I rechecked the timing, the distributor location did not really need any change, it was good already.
So my recent figures are 575-600 RPM in Drive (auto trans), 25 deg dwell, dwell specs says 27 deg, I may try to enlarge it again.
The vacuum in Drive is 19 in.
A problem I see now, is when returning from higher RPM, the idle speed is a few 100 rpm higher. I tried to lower it with the idle speed screw, but I'm bottoming on the dashpost screw. So I realize when I push the throttle lever forward, this is compressing the dashpot a bit, so I get the 575 value in drive.
I need to learn about this dashpot feature and adjustment.
After all that, I still fell a little bit of hesitation at low speed during acceleration when I start from stop. If I leave fast, not as noticeable.
In any case much better than before, so the trouble wasn't timing but too lean a mixture.
I can feel more power now. But I would like to get ride completely of this hesiation, even though it is small. I'm getting picky. Any more advice? You hit it right on the head.
I'm left with the dashpot adjustment for my idle (may be), dwell angle 2 deg too low. I wonder if this can influence the slight hesitation at low speed. I may play again with the timing to get the optimal point, which would be about a 1/16 in. rotation CCW before the popint where you can just start to fell pinging at high speed.
Thank you so much Rob and the others for advices.