mpg display for carb engine
 

Back in the 80's there were several trip computers that would hook into a flow transducer and calculate fuel mileage.

So if you have a carb what do you do now?

Airplanes have that sort of gauge but it is not really what a car needs.

Something that would calculate the fuel flow with the speed.

Any ideas for a non fuel injected car?

besides fuel injection!!:)

Thanks! Retrorocket

Little flow meters are available for diesel, probably gas too. You would need to calibrate 'em iirc, and also need something to interpret the data and an electronic signal for speed but those are both doable iirc. They don't tend to be very accurate for semis, but iirc it's because no provision is made for fuel density at different temperatures, so if you had something to measure fuel temp, fuel flow, and speed, along with a microproc to perform all the calcs, maybe some memory storage, and a little lcd display as well as the desire to put it all together it's definitely doable imo.

retrorocket, what do you drive? I would also like something to measure my MPG instantly. I saw some of those flow meters on ebay, but you would still need to feed it to a computer for calculations.

How hard would it be to grab odometer readings for the calculations. How do speedometers measure back in 1963, is it all mechanical or electric at some point?

Easiest way to get the speed measurement would be to use one of those magnet speed sensors. They are pretty simple. A magnet is attached to a brake rotor or drum and the sensor picks up every turn of the wheel. Something like these https://trailtech.net/vapor_speed_sensors.html

Then you would need to use a microcontroller of some sort to get the flow rate and wheel rotation and calculate the mileage from those numbers. All in all it would not be that hard to build as far as soldering a few components together and the program running on the controller would be fairly basic but if you don't know how to do this stuff then it would be really hard to figure out how to make it work.

there is a device (from the 80s) that you can buy on ebay for around 100 USD. Wish I could remember what it is called.

Is it that thing we talked about way back when?

that's it

Damn, what was that thing called. Some british guy had one...

My buddy had one in his car around 1984.

I remember there were 4 or 5 different kinds.

3 or 4 brands

to answer a question

I have a 1966 Oldsmobile F-85 and a 1966 Ford F100 camper special

I am putting a new engine and trans in the truck.

I have a 390 with a very very small solid cam and a TKO 600 5 speed trans.

I intend to run a Qjet carb that the mixture can be changed by pulse width.

I have a controller that will let me control part throttle cruise while driving down the road. It has had an O2 sensor and vacuum gauge in it for 10 years and I have really studied the timing curves and fuel curves.

I intend to run a 2.5 rear gear and a 31 inch tall tire with a .72 overdrive in the trans.

If I can break 20 mpg I will be happy.:)

I also have a very nice 1985 RX-7 which was the last year for the 4 barrel carb.

I know that mpg is not the strong point of the rotatory but I may end up playing with that or sell it and get a Corvair! Who knows about that one.

Retrorocket