Technical Your RPMs at 70mph

GPS speedo is pretty damn accurate. 3.78 gear 7.50x16s

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You better get some gas!

 

300 hp 327, 2650 rpm at 70mph with 31.5" rear tires in 32 roadster. it like this very much.

 

Some without corn in it this time

 

Sending unit is bad... I hope...

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I find the method that works best for me is to not run a tach, then drive as fast as I want and "trust" the rpms are right about where they need to be.

 

Daily Drivers with 235 and 261 Chevy 6s since 1995 and close to 200K miles total.
3-speed with torque-tube into 3.55 rear
Around 3000 rpm at 70 mph and 20 mpg
3000 lbs. car and truck.
Water temp at 185 degrees at the most even in the hottest triple-digit summer days in the CA Mojave desert, driving all day.

 

My avatar running a '40 flattie, 5-speed with .8 5th gear, 235/85-R16 " rear tires (almost 32" tall), 3:54 banjo rear - 2350 rpm @70 MPH .... sorry - I just reread your post looking for guys running a 3 speeds ....

 

I fall into the category the poster didnt want to hear from, but looking for some input. I have a 40 Ford sedan, stock Camaro 305HO except for a Holley 4bbl, 700R4, 2.79 gears in a Plym 8-3/4 rear end, 235-70-15 BFG's on the rear. I get 21 mpg at 1900rpm at 70 mph, to test it last summer I ran 82mph at 2200 rpm for a 200 mile stretch....still got 21 mpg. a friend says I should change to a 3.73 ratio & get better mileage, but I am afraid to screw with it & maybe get worse mpg. opinions????

 

Nice avatar Steve.
Lower ratio would increase rpms. maybe a compromise would be 3:23.

 

2000 RPM @ 70 with my 401 and 700R4 OD trans and 3:55 Ford rear gears.

 

Make a test run with trans down one gear and see what the milage is and if the engine noise is tolerable?

 

39 zephyr 3 speed behind my 39 flathead. 26-2800 65-70. 3000 @75


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yes, she is.....fitness model Jordan Carver.....google her

 

For YEARS, before those new fangled OD transmissions came out, we would build our Hi Performance street cars at almost 2:1 set up, maybe closer to 2.25. We drove everywhere that way - daily driver, long trips, hell it was usually our only cars. So 70 = 3100-3300 rpm range and I put hundreds of thousands of miles on my Hot Rods that way. Just weren't willing to give up the stop light acceleration for lower RPM's on the highway, never even considered it.