Drastically Lower Your Fuel Consumption With a Lawnmower Carburetor: Here’s How

A bit tongue-in-cheek? Perhaps. But bolting a one-barrel lawnmower carburetor on your gas-guzzling V8 to increase fuel economy worked in this case. At least it did in this video. So why would someone take something that is obviously both restrictive and inferior, to get gas mileage from the fuel pump into the engine? That’s the point; because it is restrictive and inferior.

How can a lawnmower carburetor work with a Detroit V8?

Lawnmower carburetor
Lawnmower carburetor adapted to V8 engine | YouTube

This lawnmower carb swap takes a puny gravity-feed one-barrel spritzer and meters the gas. But because it is small and restrictive, it means you’re dumping less gasoline into your engine. Less gasoline means more miles per gallon, if you can get it to work. 

It also means less air into the mix, which combined with less gas and a spark are the three components that make an engine spin the crank. Restricting the gas flow was one way Detroit tried to increase efficiency in the 1970s. That ultimately led to what we have now, which is directly injecting gas into cylinders through little computer-controlled injectors under pressure. 

Internal combustion engines are like a vacuum cleaner; the more air that goes in and is then quickly expelled, the better the performance. So with less air and gasoline, the less efficient the engine is. But if you’re looking for fuel economy, this is not a priority. 

What about the simplicity of the carburetor?

Lawnmower carburetor
Lawnmower carburetor adapted to V8 engine | YouTube

Thunderhead 289 took a float bowl-style lawnmower carburetor with needle jets for this experiment. No accelerator pump for this bad boy. The vacuum will replace the push of an accelerator pump.

Let’s be clear, carburetors are dinosaurs. Current fuel injection technology is exceedingly superior. But that’s not what this is about. So you can poke holes into this exercise, but it isn’t about where we are in 2022. Have you not seen gas prices?

To connect the carburetor to the intake manifold, Thunderhead 289 used 3D printing to make an adapter to the four-barrel intake manifold. Using an AutoDesk Fusion 360 program, and PETG Carbon material, he adapted the carb to the engine. 

Will this burn up the V8 engine?

Lawnmower carburetor
Lawnmower carburetor adapted to V8 engine | YouTube

Will it lean out the mixture, which could result in burning up the 302 ci Ford engine in the Maverick test vehicle? That can be controlled to some extent by spark timing. But it is a huge gray area as to exactly how the engine would respond, and what it will take to keep it running. With a less-dense cylinder charge, it is possible to pull off. 

Thunderhead 289 decided to start the experiment with a rich mixture. And then, just like that, a little adjusting here and there, the small block Ford engine was idling and having decent throttle response. For a one-barrel carburetor, that is. Adjusting down the fuel pressure with an inline regulator helped smooth operation out. There is good throttle response, but that’s with no load on the engine. 

It won’t win awards for having a lot of power. But if that’s what you want, you should consider a big block Ford or Chevy engine. And the subsequent nine miles per gallon. That’s not the point of this exercise. Actually, the only point is to see if a crummy lawnmower carburetor could actually work. It looks like it does.

RELATED: Want Better Fuel Economy? Follow These Simple Steps from AAA for Any Car!