Whats the best MPG you get from a 230/250/292?
What carb, rear gears, OD or not, etc.
I want to factor this in to whether I go 6, or not.

not interested in a 4200, I know they will get better mileage.

BEST I,VE EVER GOT DRIVING IT 'EASY" IS 14MPG BUT I HAVE 3.73 GEARS. ANYTHING OVER 60MPH AND MILAGE GOES DOWN QUICKLY. 70 MPH ITS 9-10 MPG. THIS IS A ALL STOCK ENGINE.......

1970 bone stock Nova 4 door, 230 and 2-speed powerglide. Engine worn and needing a rebuild, but ran ok. Got 17MPG mixed, mostly highway driving. Not a very heavy foot, there was no difference whether I was at 1/2 throttle or full throttle, didn't go any faster So I took it easy. This was in Florida, virtually ZERO hills, all flat.

65 Chevelle wagon, street built 250, cam , headers, ported lump head, 5 speed no overdrive and 2.56 gears 20 MPG going 75-80. Also never baby it off the line or up a hill.

65 Elcamino 292 turbo 17 MPG going 70-75 with 700r4 and 3.55's.

23 MPG, mild 250 in a 3200 LB Camaro
400 CFM Carter AFB & Quadrajet 4:10 gear OD 5 spd manual

Not trying to get mileage mind you, & was not an ideal combo for mileage.LOL

"not interested in a 4200," horray! keeping it old school!

MBHD

strictly wind resistance

LOL, yep I am building a 1941 Chevrolet Coupe. Low and Slow!

I do plan to put a lot of miles on this sled, and just trying do decide on a ideal engine.
It has to "look right" as well as deliver on the highway.
My thought is a 292(w/2 webers)/3spOD/jag rear w/2.88.
Thoughts?
Thanks for the responses.

Old School is getting newer all the time.

38 Chevy with near stock 250, 3.23 rear with OD tranny: 19 MPG on road trip, some hills, driving speed limit on interstate hwy.

Is a 292 less efficient than a 250?
I already have a 250, but like the idea of the extra torque of the 292 to pull the 2.88 gears.
Jags also came with 3.31 and 3.54 gears, but 2.88 is most common.

292s are not known to get great milage but they can pull whatever gears you got. It will do better with 2.88s than a 250 especially if you are throwing an OD between 'em. Think this out before you invest a lot. What kind of driving will you do the most of and where will your RPMs be while you are doing it?

I'm running a 292 with cam,lump port head, triple DCOE Webers.
4.11 : 1 rear end, 4L60 transmission. All in a '35 Chev Sedan Delivery.
I get around 18 mpg.

Will Willis

Sounds pretty good!

What size are your Webers & the choke tubes?

Thanks

MBHD

The Webers are 45DCOE with 38 mm chokes

Will

I plan to build it for the freeway since everywhere I go seems to be a couple hours.
I'd like to get at least in the low 20's

Last April i spent 2 weeks driving a '59 Ford wagon out west and back.
it was a 390 with an AOD and got 15 MPG.

This '41 is a clean slate, so just trying to do the research to do this car right.
I have a 250, and a '55 3sp OD, but planed to build a 292.
I'd like to go 6cyl as a nod towards the 216 that came in the '41.
Love that 6cyl music, perfect for a taildragger.

I appreciate y'alls advice.

If milage is more important than torque build the 250 you already have. It will be easier to get 20s from it than a 292. I don't know what the first and second gear ratios are in your 3 speed and how they would work with the Jag rear end ratio. To get good milage the engine can not be working hard at your cruising speed. Look at the post by Tom Lowe about his recent trips in his 250 powered wagon. Remember that any money you put into the head, headers, intake, cam (with electric fuel pump), and ignition won't be lost if you later decide to go to a 292.

My 250 is a runner, fairly fresh rebuild from my '64 PU.
so valid points, thank you.
I will build a engine for the finished car though.

'41s are one of my favorites. A friend had a '41 coupe with a 261 in it. When he wrecked it I got the engine and put it in my '40 pickup. Keep us up on your project. Beater

So it seems with proper gearing and making sure the engine breathes well and isn't being overworked, a 292 can get okay mileage. Basically what I am trying to accomplish with my 292, to get efficient power out of it.

Keys to mileage:
1. slow the engine down
2. hot air to carburetor
3. as much vacuum advance as it can stand
4. lean cruise mixture (main jet in Holley, metering rod lean step + spring tension in Carter, Rochester)
5. 195 thermostat

RPM's will be 1800-2100 for cruising at 65-75 in OD. Direct will be 2400-2800 for the same speeds. Definitely will be heating the carb. Check on the VAC-ADV, Carb lean cruise mixture, and 195 thermostat. The warmer thermostat also allows more heat from the heater in the cold months, so it's a win-win for comfort and better combustion.

Thanks Panic, I will implement these as I get mine pieced together and back in operation.

A few more general ideas that affect mileage on my site here:
http://victorylibrary.com/mopar/mileage.htm

One more to add to the mix: 68 gmc, 292 with 390 Holly, electronic ignition, timing set with vacuum gauge; don't remember exactly what but well advanced from stock. A833 OD transmission, 3.73 rear, turns about 2000 at 60 mph. Gets 17.5 to 18.5 driving local, no long trips.

The 390 is ideal (assuming the manifold is good) with those tiny primaries.
Just for a test: only change the size of 1 main jet at a time (yes, it may do a bad mixture distribution thing), the point is to approach best cruising vacuum in small steps.
To get the mpg really big, pick a PV that remains closed at any speed you will reach, even with mild acceleration. Accept the slightly slow tip-in response as the price of better mileage.

Just to be clear, the PV opening point is not speed dependent, it is manifold pressure (i.e., vacuum) dependent. A PV with a larger number (e.g., 85) starts to open at a relatively high manifold vacuum, in this example 8.5"hg manifold vacuum. A PV with a relatively low number (e.g., 35) starts to open at a relatively low manifold vacuum, in this example 3.5"hg manifold vacuum. Keeping the power valve closed as long as possible on accels and heavy cruises means using a PV with a low number (at the risk of possibly running too lean with a heavily loaded engine).

Just as an aside, the 390 we put on our 240 powered Anglia worked fine out of the box except for needing a much bigger pump shooter. But we were not trying to optimize mileage. That's what late model tuner DDs are for.