Replace it with an different Holley. The 4180 is made by Holley to Ford specs and is an emissions carb and there isn't much you can do to it. I replaced the 4180 on my 1984 460, C-6 and 4.10 rearend in a F-250 crew cab, super duty (light 1 ton). Stock 6 to 7.5 mpg was the best I ever got. After the install of a Holley 1850S with a 2 stage power valve and reworked vacuum secondary spring, later opening. It added just over 1 mpg. I recurved the dist, to 35° mechanical advance in at 3500 rpm and with vacuum advance 50° total. The mpg is right at 10 mpg. The exhaust is both head pipes dump into a single 3" pipe, muffler and tail pipe. Other than going to headers it as good as it is gonna get.
Replace it with an different Holley. The 4180 is made by Holley to Ford specs and is an emissions carb and there isn't much you can do to it. I replaced the 4180 on my 1984 460, C-6 and 4.10 rearend in a F-250 crew cab, super duty (light 1 ton). Stock 6 to 7.5 mpg was the best I ever got. After the install of a Holley 1850S with a 2 stage power valve and reworked vacuum secondary spring, later opening. It added just over 1 mpg. I recurved the dist, to 35° mechanical advance in at 3500 rpm and with vacuum advance 50° total. The mpg is right at 10 mpg. The exhaust is both head pipes dump into a single 3" pipe, muffler and tail pipe. Other than going to headers it as good as it is gonna get.
It's all about making as much torque as possible and then not using it . Might try advancing the cam if you have that nasty retarded chain...
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'85 F150 4x4 300CID, NP435, 3.08's, Factory 15x8's, 31" Goodyears, Lock-Right in the back.
I have a 88 Georgie Boy witht the same set up. I replaced the timing set-up, an RV cam and had higher gears put in the rear end and I increased my mileage 20%...It increased from 5 MPG to 6 MPG (that's a 20% increase)...But I drive it 65 + mph too.
The best mileage tactic is to flat slow down. I quit the 60 - 65 mph stuff and now run about 55 and gained 1 mpg just from that even with 4 quads on a double axle trailer behind the truck.
Great stuff guys....I'm in snow country Canada so it's in storage right now but this gives me something to work with and I have some time to source out a carb. Bear do you know, is there much difference between an 1850s and the 4160 series Holley.
Yes I must say I push it pretty hard, not under 65 on a good highway, probably a good to slowdown even for safety.
The 1850 is a 4160 carb. 4150, 4160, 4180 and 2300 are series of carbs. List numbes such as 1850 or 1850S are the actually numer of a carb. The difference between a 4150 and a 4160 is that the 4150 has a full size metering block, with regular jets while the 4160 uses a metering plate for jetting. The 4180 is an emissions modified, for Ford specifically, 4160 carb.
Here's a list of all Holley carbs by list number and the parts they use:
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. Might try advancing the cam if you have that nasty retarded chain...
The other side of green...
