Fuel economy

Kahuna

Kahuna

Well-known member
Thought I'd share this with the group.
I just returned from a trip to Chester, CA., where a nice car show is held.
I started from my home in Brownsville, CA with a full tank of gas. The total round trip distance was 298 miles going from an elevation of about 2200 ft down to sea level, then up to an altitude of 4500 ft.
The car is a 32 Tudor sedan with an 288 CI flathead, Potvin 425 cam, 2 4bbl carbs, etc. Rear axle ratio is 4.11, but I have an overdrive that reduces the final drive to 3.21 (not used too much on the climb up, but used when possible).
Mileage on the way up was 16.9 mpg, with an overall of 18.1 mpg
Flatheads can be real good, I think
Thought I'd share
Jim
 
I've talked to Jim, he has a beautifull set up there. I am running 276 with four 97's straight linkage T5 with 3:50 gears. Don't know what that finally ratio is in OD but at 60MPH with a GPS I'm turning 2000RPM. On secondary roads I get 18mpg. Walt
 
Having been working on improving the fues mileage of our flatheads, I've found that yo must start in the combustion chamber it's self. One reason you shouls try and keep the piston to head clearance very tight. Next the AF in cruise in the hi 14's low 15's, mid 13's in WOT. Followed by a good ignition curve, you need a fair amt of adv to burn a lean mixture. Last but not least is the basic design of the intake system allows the AF mixture to better vaporize before the plug fires. I like to run these engines in the 180 plus range. This is something that takes time and effort. However most people like to tell fish stories, it's the nature of the breed.
 
I think about 18 MPG is the best I expect with my car.(276 and single 4 brl.) I have checked it several times. The 40 sedan, with Mitchell O.D. is heavy, with my load(3700), and it is not good from the aero viewpoint. However, there is much to be said about the driver when MPG is the focus. I am not a good MPG driver. I installed the MSD adjustable timing device and mounted the dial on my radio grille so I can adjust timing while driving. The crab distributor has limited capabilities when searching for a better "cruise" timing setting. Unfortunately I have not taken the car on extended road trips since installing the toy so cannot report on an improvements.
 
JWL and everyone:
I expected far less than what I got.
I'm now thinking that on a regular road (not so hilly) that the
car will do 20, maybe more.
On the trip I described, speeds were 65 max, 45-55 normally.
Oh, not really hammering it, so no secondaries were used that I remember.
Yes, 51 merc is correct. It's just like running 2 Stromberg 48's until you
punch it
 
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I'd say that's an excellent result and you obviously have the engine set up very well. Especially so considering the one off manifold and carb setup.

Mart.
 
Kahuna, I talked to Willie and he pulled the old VW trick on you where he snuck in 5 gallons of petrol in your tank at a stop on the way. Next part of the trick is to siphon off 5 gallons from your tank during your next day trip.:p
 
My Dad had a 65 Tbird and a guy asked him in sarcasm what he got for gas millage, his answer was "anything I want"! That being said I just got back from Lake George 506 round trip from Ri and got 18.2 mpg with a 276 in a 37 sdn. I have a Mitchel OD with final drive of 2.82. Engine built by who else but Ol'Ron.
Don
 
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