1984 F150 2WD auto TFI IV ignition feedback carb 205K miles Stock
I had been having a bad miss on one of the cylinders so i did a compression test and found one cylinder slightly out of spec.
I had purchased a used 1975 300 engine from a friend. So i took the head to a machine shop and had it rebuilt, plugged the air injection holes with 1/2-20 socket head setscrews, and swapped it out. The only difference between the 75 and the 84 head was the air injection and the studs were different on the rockers.
I tightened the rockers down until i had a gap with the lifter callapsed of .150". The spec for the 84 and the 75 is .125-.175".
The engine runs real smooth now.
I have been reading about using a vacuum gage to adjust the carb so over the weekend I had the vacuum gage hooked up. The vacuum at idle is between 19 and 20 inches and seems to vary in this range a little as the rpm varies. When i rev it up it drops but picks up rapidly to around 25 inches.
At idle i get a little Flutter of about 1/2 inch, is this normal
How steady should the vacuum be.
I have been gettin about 14 mpg at highway speed I used to get about 17. I rebuilt the carb about a year ago. And have disconnected the EGR due to a cracked exhaust tube. Otherwise everything is working good. I have the origional cat and exhaust.
Any suggestions?