Hey everyone! I have a 1956 F100 with a 272Y Block. I am trying to adjust the carburetor, but I can't seem to find anywhere on how to adjust the screws or the idle. Can someone PLEASE point me in the right direction. She runs "great" but she backfires and pops when I let off the fuel. I adjusted the timing although it didn't work unless I left the the vaccuum hose on....so....there it is.
I was looking at my 56 shop manual. It talks about an "depopper" valve that was used on the throttle body of the original, dual barrel carburetors. ( I am paraphrasing from the manual now) it was supposed to eliminate the loud popping noise/after fire from the exhaust when the truck is being decelerated with the throttle closed after high speed operation. There is an adjustment procedure for it.But first let's make sure we are talking about the original Carburetor. And make sure your basic adjustments are in order. These would be making sure your timing is set correctly. The manual says for a 272 it should be at 10* before TDC and it is set with the distributor vacuum line removed and plugged. Then check for correct float level to see if you are working with the correct fuel level then setting your idle mixture screws , then your idle speed. Then go back tweak your idle mix screws again and reset idle speed if needed. If you by chance are using an automatic transmission do this while a helper is in the truck in Drive with wheels chocked and applying brakes. There is a procedure on how to adjust the depopper valve. But first let's find out about your carb model and double check your basic adjustments.