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Gas mileage with Duals


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assuming the 38's are properly tuned and you do not change your driving style, yep...you are going from 38/38 to 40/40/40/40. even if you choke them down to 30mm and small jets there will be a difference. it may not be much, but...

and then there is the sound factor. dual DCOE intake noise is loud and intoxicating. it will be hard not to drive more aggressively...leading to more fuel usage!

people who are concerned about mpg shouldn't be going down the DCOE road! ;-)

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..."..what woulod I be compromising in way of mileage?"

lets see - when straying from

the original frugal BMW SOLEX carburetor:

add more throats

add more jets to flow gas

add improperly set up jets & poor air/fuel mixture

add a foot that keeps pressing the pedal

add poorly set ignition timing

add big fat tires

.............. looks like your in for buying more gas in the future


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CD's idea or suggestion is that the road to more hp is a slippery slope.

Getting dual DCOE's set in proper tune is a daunting task that can take a long time. There are all those choke sizes, jet sizes, and emulsion tubes..... On a personal note, I have gotten 40's close through dumb luck and a good ignition set up. As I said..... Close and NOT perfect.

Back to CD's comment. More carb, more hp, more speed, more tire (tyre for you Les) you are going to need more seatbelt for safety.

Behold the wisdom of Brother CD.


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One of my favorite sayings...

"you've got to pay to play"...

I'm currently running a 38/38 with a 292 cam and 10.5 to 1 pistons. Very happy with the setup but i have been considering side draft 40s. Some people seem to love them and think they are simple. Others seem to say they are impossible to tune perfect. I didn't realize the gas mileage could be all that different but it makes sense it would be a little worse. Seems like it really boils down to how heavy your foot is. I seem to get 25+ with my 38/38 in 5th gear which is more than enough for me...

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I just got back from a drive.The dual weber 45s are a blast.They sputter a bit and fart at first start but then are great.Tuning is a real challenge for me.

And back to the topic,my milage sucks,teens in town is about it but the rorty fun is worth the extra gas.


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Marshall, guess I should stick with my EFI project. i just LOVE he sound of duals but I also know i tend to drive fast which equates to lots of extra gas

You can have it both ways. With EFI, you can haul ass (and drink gas) or cruise nicely and get outstanding mileage.

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