Gas Mileage

[gogo34]

My '66 IIa seems to run fine (although I've never owned another to compare it to) but I'm wondering what I can do to improve my gas mileage. It has a 2.25 petrol engine, electronic ignition conversion, appears to be timed right but, I'm only getting about 10 mpg. I've been using 87 octane gas from the local gas station as it's the lowest octane I can find. The only negative I can see is that it has a pretty pungent "gas" smell when running. The smell's not in the cab but noticeable if it's running and you step outside the truck.

Any ideas/suggestions?

[stomper]

Sounds like you have a leak somewhere between the pump and the carb. People running Rochester carbs get lower fuel mileage. Often in the 10-12mph range. What carb are you running?

[gogo34]

Sounds like you have a leak somewhere between the pump and the carb. People running Rochester carbs get lower fuel mileage. Often in the 10-12mph range. What carb are you running?

I am running a Rochester carb so, maybe my 10mph is normal.

Thanks!

[TeriAnn]

Sounds like you have a leak somewhere between the pump and the carb. People running Rochester carbs get lower fuel mileage. Often in the 10-12mph range. What carb are you running?

I ran a Rochester for almost 2 decades. Flat highway driving 50-55 MPH averaged 15-16 MPG. Combined round town stop and go driving was closer to 7 MPG.

I had the Rochester with the smallest venturi and was running a 51 jet. Mostly 0-1000 feet above sea level on 100% petrol. You don't get as good fuel mileage with a blended fuel.

I would take the truck to a place that can measure your air to fuel mixture to see how rich your engine is running. Could be you need to jet down a couple sizes. My rochester came to me with a 56 jet and if I just glanced in the direction of the choke knob the engine would flood.

The Series truck is not remotely aerodynamic. If you have a roof rack it will cost you fuel mileage.

[bensdad]

My 60 Series II is getting great mileage these days as I have yet to get it running

Wondering which fuel is better however. Unleaded or Premium?? Any thoughts on this?

Thanks!!

[TeriAnn]

My 60 Series II is getting great mileage these days as I have yet to get it running

Wondering which fuel is better however. Unleaded or Premium?? Any thoughts on this?

Run it on regular. The compression is not high enough to require premium.

[bensdad]

Thank you. You always offer such great advice!

[mearstrae]

The older engines also require a lead substitute in the fuel to protect the valve seats. Hard to get good mileage with the fuels that use alcohol in the blend, it's also hard on old rubber fuel lines.

"95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S

[LaneRover]

I used a Rochester carb on my 69 109 p-up and with an overdrive I got about 15-16 mpg.

The engine is one that was re-built by the British military.

[TeriAnn]

The older engines also require a lead substitute in the fuel to protect the valve seats.

Yes and no. Unmodified heads had problems with unleaded fuel. But when people get valve jobs they tend to have hardened valve seats put in as part of the valve job. With hardened seats you do not need a lead substitute. Most Series trucks that have had a valve job in the last 15 or so years have hardened valve seats in them.

If you don't have hardened seats it doesn't mean that you develop a problem the following day or week. It usually take s thousands of miles before the valves stop sealing. So when you get a valve job check for the hardened seats and if there are none have them installed. The seats are a standard size that any automotive machine shop can readily source.

While the miles between valve jobs would be less without hardened seats, it is no big deal to have hardened seats installed and it is probably cheaper than buying a bottle of lead substitute for every fuel fill up.