Amazing Vintage Car Accessory

erco

erco

Senior Member
I'm officially mad at myself for not thinking of this product, which IMO could have been done with a Picaxe.

I've been AWOL from the forums for a long time now, focusing on getting my old classic car back on the road. Everyone says "I wish I kept my first car." Well I'm the idiot who did. In 1980 in college I bought a 1967 Chevy Corvair, mainly because it's a weird car. I like weird stuff. Rear engine, air cooled, kinda Volkswagen-ish. More recently, it sat rusting in my garage for 22 years while life happened. Then it became my Covid project in 2020, mostly back-burner but finally I pushed this year to get it driving. Body is still rough (I'll get to that eventually) but she's mostly new underneath from bumper to bumper. 3 years of rebuilding the front & rear suspension, all brakes, electrical, fuel tank, engine, differential, transmission, wheel bearings, etc. She drives great now and I'm having a ball:


Anyway, now I'm back into gas and carburetors (my car has 4) and engine tuning. Hey, EVs are the future so I want to enjoy my gas car while I can. Youtuber "Thunderhead289" has come up with a new microcontroller system to adjust the air/fuel ratio on the fly. I think Luke's "Carb Cheater" is the coolest thing I've ever seen to bring old cars into the future. Basically he installs a plate under the existing carburetor to introduce air into the intake manifold and adjust the air/fuel (A/F) ratio on the fly, using a controllable air bleed and a wideband air/fuel sensor. Simple but effective. It's a standalone system but it Bluetooths to your phone for customizing and datalogging.

Man it's ingenious. Should have been me but Luke beat me to it. He's selling the whole system for under $400 USD, that's dirt cheap IMO. It won't fit my Corvair but he's got me thinking about how to tweak it, or build my own version. https://www.thecarbcheater.com/

 
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oracacle

Senior Member
Seems a little over priced. Haven't seen the vidios yet as I'm at work, but a fuel injector conversion kit isn't that expensive. Depending where you look and what you need as little as £180.

Honestly since getting a bike that is full l fuel injected and not dealing with carbs I have realised how much of a pain they were
 
hippy

hippy

Ex-Staff (retired)
erco said:
Man it's ingenious. Should have been me but Luke beat me to it. He's selling the whole system for under $400 USD, that's dirt cheap IMO. It won't fit my Corvair but he's got me thinking about how to tweak it, or build my own version.
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I can understand wanting to keep a vehicle more original than a conversion to fuel injection would be. And, in principle, it's fairly simple, adjusting fuel mix additionally to what exists, has the advantages of being something which can be removed and have the car still work, improving performance when fitted.

It's basically real-time carb-tuning. I'm not sure how complicated such algorithms would be, how well a PICAXE would perform, but it does seem one of those projects which can go from 'helps a little' to wherever you could take it. With a fall-back to no worse than it is without it, it's perhaps an ideal project for a petrol head.

The usual caveats and warnings on automobiles, safety, and insurance apply.
 
PhilHornby

PhilHornby

Senior Member
erco said:
Basically he installs a plate under the existing carburettor to introduce air into the intake manifold and adjust the air/fuel (A/F) ratio on the fly, using a controllable air bleed and a wideband air/fuel sensor.
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That can only weaken the mixture though - so presumably it would need to be set deliberately rich, in order for it to change it (A bit like the 'pendulum clock correctors' that have to run deliberately fast, so they can stop it for a while).

There is then the question of what air-fuel ratio it should deliver and when (idle, Wide-Open-Throttle, cold-start etc). Might it need any 'Accelerator pumps' disconnecting?... It could become your life's work!

Maybe a starting point could be a Picaxe ADC reading a lambda sensor? - it might give an interesting insight. (You might need other data logging; at least RPM, maybe Air temperature, throttle position etc?).

I have to say, that as a previous owner of many four-carburettor motorcycles in the past, I never felt the urge to adjust the air-fuel ratio (except maybe the idle). I did on occasion, embark on synchronising them to open together - but that's a whole different kettle of fish.
 
erco

erco

Senior Member
PhilHornby said:
I have to say, that as a previous owner of many four-carburettor motorcycles in the past, I never felt the urge to adjust the air-fuel ratio (except maybe the idle). I did on occasion, embark on synchronising them to open together - but that's a whole different kettle of fish.
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My car also has four carbs, which makes it that much more challenging.

140HP.jpg
 
PhilHornby

PhilHornby

Senior Member
That Distributor and Ignition Coil would be high on my list of things to improve. Kits to replace the 'points' with a magnetic sensor have been around for long time, but a trio of wasted-spark motorcycle coils could see the Distributor consigned to the bin eBay as well. :unsure:

I'm sure a Picaxe could be involved, looking after the vacuum advance!
 
PhilHornby

PhilHornby

Senior Member
Oh how true. I learned that lesson the hard way :(

Nearly 40 years ago, my ex-wife's car was recovered home, after breaking down. It would run for a few seconds and then stop - with a visible splutter from the top of the carb. The 'highly-skilled' :unsure: recovery person said it was the carburettor. Since we were due to go on holiday in said vehicle, I rushed out and bought a 'carburettor overhaul kit'. It made no difference. I then rushed out and bought - at great expense - a new carburettor. That made no difference either :cry:

It was only at this point that I plugged in the Timing Strobe light. The engine stopping and the light going out coincided exactly! A test rig comprising the Ignition module, coil, 6.3VAC transformer and a Spark plug easily reproduced the fault on the bench. One new ignition module and problem solved :)

You live and learn :)
 
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papaof2

Senior Member
Good ignition:

I once owned a Chevy Vega :-( However, I added a capacitive discharge ignition and the next start told me it was an improvement - the idle speed was up a couple hundred RPM just from the improved ignition. It also improved the gas mileage. That might have worked even better if it had a PICAXE to monitor engine vacuum and manage the intensity of the spark depending on the load. Considering the year, the CD ignition was "state of the art" ;-)
 
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