400 vs 440 in a 76-78 New Yorker - noticeable difference?

[WissaMan]

Yeah, I think anytime you see the milage go to 99 or infinite the fuel injection system has cut the fuel completely. It usually doesn't do it until the engine is warmed up though, at least the cars I own. And won't happen below a certain RPM

But that's why it's better, from a fuel consumption standpoint (and brake pad standpoint), to let a FI car engine brake down a hill rather than coast in neutral. Unless it's a "U" and you're looking to pick up speed to coast part way back up the other side....

 

[WissaMan]

BTW, I had a chance to do a 0-60 test the other day. From a dead stop on a flat, straight road. Measured 10.3 seconds on my "0-60" phone app. I don't know how precise it is, but it feels about right. I had to let off a bit because it actually pealed the tires when I tromped on it, which surprised me. I didn't think the old girl had it in her!

 

[Rustyrodknocker]

I have a few anecdotal milage experiences..
My 83 D150 318 A833od with hiway gears did as well and maybe better in 3rd gear on the freeway. To much gear to push for the little 18. Had horrible throttle lag under 75mph. Drove like a normal car as expected with a tall gear and 1:1 3rd.

Same deal when I went from an 80 v6 camaro commuter to a 90's bar of soap caprice with 305 700r4 and a 3:08.
I babied it for a month thinking I could get equal to camaro milage with the od. Not the case. Had a busy as hell week after work so I justified leading the pack in the left lane and bearing cost of fuel for the week. Mileage went up... 305 can't push all that gear at low rpm..

A buddy was building flipper muscle cars over 20 years ago I and selling on ebay,

He painted up his daily driver 318 coronet and dumped in a used 440 for the desirability factor. Ran it over a 100 Mile mountain pass to deliver to the shipper. Best mag ever recorded.. we guessed being young and dumb that the big block just didn't have to work very hard.. my own 45o coronet can really behave if I do the same..

I swapped a 4 barrel holley onto my factory 400 two barrel pick up. The mileage plummeted!! Adding two barrels may have well have been two more carburetors..
And the cost of tires would have been unbearable if I wasn't getting free tires from the dump.. but holey **** man! .. that thing would literally do 1/8th mile long burnouts all day long! It could turn bias ply directional M&S's into drag slicks in a week..
But I never figured out the mileage thing..

 

[WissaMan]

I swapped a 4 barrel holley onto my factory 400 two barrel pick up. The mileage plummeted!! Adding two barrels may have well have been two more carburetors..

I have learned that aftermarket carbs are usually not tuned very well out of the box for any particular engine (except maybe a chevy 350 with an intake and headers). I think they send them with an overly rich tune so they run decent if you just drop them on an engine, since that's what most people do. Put another way, a lean carb will run terrible, but a rich carb will run "ok" -- but just be down on economy and power. So from the factory they set them up on the rich side so you can run it with acceptable results, but it's far from optimized.

 

[Rustyrodknocker]

I have learned that aftermarket carbs are usually not tuned very well out of the box for any particular engine (except maybe a chevy 350 with an intake and headers). I think they send them with an overly rich tune so they run decent if you just drop them on an engine, since that's what most people do. Put another way, a lean carb will run terrible, but a rich carb will run "ok" -- but just be down on economy and power. So from the factory they set them up on the rich side so you can run it with acceptable results, but it's far from optimized.

I think this one's issue was throttle blades position while in motion.. it seemed to go from off idle to wfo. At every stop sign..
Sometimes I would pull the air cleaner assembly off and it would pull down the center of the hood on the 72.. it just never got old and it never broke.