carb question

[ezernut9mm]

302 with the stock style 2bbl. the truck seems to run good and use about as much gas as is expected for one of these old trucks.
it idles well with a slight lope and i'm not sure why. runs down the highway good. the main problem i have is a slight "surge". it is very noticeable in first and second when decelerating or keeping a steady speed/rpm. say like a steady 10mph in first you can really tell, or 20mph in second. it is not noticeable at highway speeds. any ideas?
i still need to check the timing to be sure it's right, but it starts good hot or cold and doesn't ping so i think it's at least very close. also, the vacuum advance is the dual draw type if that matters.
any ideas or opinions?
thanks.

[Alvin in AZ]

I have no idea if this is what's going on or not...
Fuel-flow changes much slower than air-flow can.

So, if you are moving along and you open it a little-bit-suddenly and you feel a power
surge or you feel a bog ...that tells you what's going on with the mixture.
Same with closing the throttle slightly, it should act the opposite way... bog or surge?

The bog or surge you feel will be before the change the throttle would have made. :)

Did I help or hinder? LOL :)

Alvin in AZ

[Dragon]

Old carb? The 2100 after 20 years along with most carbs get sloppy throttle shafts and that will cause that surge as they don't wear smoothly in a circle but are worn in the place they mostly set. This allows air into the bottom of the carbs under the jets so you get lean conditions. You don't feel it on the highway because no matter how we wish it wasn't out throttles are pushed down more to overcome the wind drag and give us more speed so you are at a different rpm.

Now this is not the same in town in first at 10 I am spinning 4000 in second I am turning 1200 in 3rd it is lugging. But if I turn 1200 in each gear then I get the same engine effects until 4th and wind drag kicks in. New carb on this truck and no vacuum leaks so no surges.

My F350 had 2 carbs when I got it both 2100s and I rebuilt both of them but I could not change the throttle shafts. So one got 6 mpg and ran rough and the other got 7 mpg and ran rough. I bought a Holley reman 2100 and went to 10mpg smooth idle and running.

http://www.oreillyauto.com/site/c/searc ... /C0359.oap?
keyword=carb&year=1971&make=Ford&model=F-100%2BPickup&vi=1119899

http://www.autozone.com/autozone/catalo ... entId=49-0

https://napaonline.com/Search/Detail.as ... 24+3999999 PS I don't pay that much for carbs.