Flags Across the Harvest #12June 11, 2019
Thank you Mr. Hipp.
I always was and still am the type of guy that does not embrace only one type of machinery. My interests are very eclectic.
I can get just as excited about an economy car that is exceptional at sipping fuel as a high output drag race engine or a new style hay bailer.
I pride myself on getting a machine to run better than it did from the factory; regardless if it is an 8 HP Tecumseh Snow King engine or a washing machine.
When you are of this ilk there is an engineering term that you embrace though it is meant to be used in a slightly different context.
The term is degrees of freedom.
According to the McGraw-Hill Dictionary of Engineering it means: Any one of the number of ways in which the configuration of a mechanical system can be changed.
To someone at the bottom of the engineering food chain as I am, I call that tuneability. I love being able to adjust and tune something.
The more tuning points there are… the happier I am.
If I were an audiophile, it would be akin to having a graphic equalizer on a radio versus just a simple bass and treble knob.
Due to this I always loved carburetors, especially ones with a multitude of adjustments.
As a farm kid there was no better way to spend a summer afternoon than taking a carburetor apart and reverse engineering it and playing with the adjustments.
On some models the linkages or pivot points would need to be tweaked with a gentle touch from a pair of needle nose pliers. Others allowed changes via a treaded component or screw.
They were all adjustable. It was just a matter of how hard you had to look to find it.
Back then we had a Gemco Giant lawn mower with a 3.5 horsepower Briggs & Stratton engine circa 1954 (the year my family purchased our farm).
It was already quite old when I was introduced to it.
Unbeknownst to my father, I took the engine apart when I was 13 and ball-honed the cylinder, scraped the carbon off the piston and fitted new rings.
I ported the cylinder head with a Dremel.
I hand lapped the valves with some compound we had laying in the barn and a wooden valve dowel I found near it.
I put it back together and it started on the second pull, but it did not sound right under load.
Nervously, I came to believe it was now too lean.
I pulled the carburetor off and with a book from Western Auto, identified the main metering circuit.
I raised the float level so it would pull-over sooner and with a hand-crank drill (I did not want to ask my dad for his electric and let him know what I was doing) I opened up the main jet, albeit a little cock-eyed.
Boy did that Briggs run now!
I then let the grass grow a little longer so I can test it out (my dyno) since I knew it used to struggle with the lawn that height.
My father could not believe how the old mower suddenly laughed at the grass it used to wheeze at.
I told him I tuned it up and put in new breaker points and sharpened the blade.
You can now imagine how devastated I was when I read that the new for 1981 GM Rochester carburetors would be electronically controlled and no adjustments could be made.
No carburetor adjustments… what is the use of living?
The automotive rumor mill was ripe with stories even though no one had yet seen an electronic Quadra-Jet or its two-barrel brother.
“All computer controlled, son. You might as well throw away your tools”, I was told by the old-timers.
A George Orwell-style prediction of a changed world four years earlier than the title of his book.
It was going to be 1984 in the fall of 1980 when the 1981 GM cars hit the showroom floor.
Back then the car magazines would put photos with callouts of engine components as part of their new car issue. Today all they talk about is connectivity.
Sure enough, the image in Popular Mechanics showed no mixture screws. It had sensors, a solenoid and an idle speed control motor. What a nightmare.
They too regurgitated the no adjustment mantra.
Everything was factory set.
To my way of thinking if the factory could set it then I could unset it.
I departed on a quest to learn about these new carburetors. It ended at the GM Training Center in Tarrytown, New York, and the AC-Delco training room of Mr. Richard Hipp. I signed up for a three-day class.
Mr. Hipp passed away in 2003 and was buried on my birthday.
The knowledge he imparted to this baby face kid in the front row that would come early and leave late, still lives on today.
Much to my surprise the electronic GM carburetor was even more adjustable than before!
I could not help but think of how great that Gemco Giant would have run if this carburetor design was on it.
The electronic carburetors were a dream come true.
Where could you find a carburetor that had a threaded and stepped adjustable air bleed?
Engine vacuum was removed as the control for the metering rods and a duty-cycle solenoid that pulsed at 10 hertz replaced it.
You could easily control the lean authority and the rich fuel flow rate.
The mixture screws worked in concert with the dithering primary metering rods.
All that was required was a dwell meter for a perfect air/fuel ratio adjustment.
A dwell of 30 degrees meant the metering rods were spending an equal amount of time in and out of the main jets.
The idle speed control motor guaranteed a rock steady rpm regardless of the load evoked.
The choke spring tension was no longer tuneable, but the fast-idle speed and pull-off angle were easily tweaked.
The secondary side of the QJ was the same as before and could be fine-tuned if you understood it.
I was in love.
I came back to the farm feeling as if I were Columbus and discovered that the world was not flat.
Few wanted to listen.
While in college I took a job in a Buick dealership and fixed all the drivability problems.
I do not want to brag but I could get an electronic 3.8 V-6 Buick to idle so smoothly at 550 rpm in drive with the A/C on that the customer would think it stalled.
Without Mr. Hipp and the Rochester carburetor that “could not be adjusted” you would not be reading this today.
Please think of this story when your young son finds his way into your toolbox.
Mr. Hipp, I owe you a debt of gratitude.