Sunday, January 6, 2019

Quadrajet Tuning: How to Connect a Handheld Tachometer

If you plan to fine-tune your Corvette's Quadrajet carburetor, one tool you may want to have handy is a handheld tachometer. This allows you to check and adjust the vehicle's idle speed while you wrench under the hood.

If you have a timing light with RPM-reading capabilities, you can use one of those, but this article is for those of us who have or prefer a handheld tachometer.

I found a used vintage RAC Maxi-Tune on eBay for about $20. Needless to say, you take your chances when buying anything used, especially electronic equipment manufactured in the 1970s, but luckily for me, the one I bought works fine.

The RAC Maxi-Tune is a multi-function ignition analyzer. It can measure low (idle) and high RPM, dwell, dwell variation, point condition, idle mixture, power balance, and more. But for this article, I'll focus on the RPM function exclusively.

Since my car has electronic ignition, I had to devise a way to connect the analyzer so it would read the engine's RPM and the easiest option was to use a solid 14-gauge copper wire to do so.

Wednesday, December 26, 2018

Quadrajet Tuning: Replacing the Idle Mixture Screws

I wasn't sure if the company that rebuilt my Corvette's Quadrajet carburetor replaced the idle mixture screws, but from the looks of them, my guess is that they did not.

They were clean, but they showed signs of pitting and wear, and I wasn't sure if that would have a negative effect on how my car idled.

So, I removed them to inspect them closely as well as take measurements to make sure I would order the correct screws. I also messaged the eBay seller with the details as to what I needed, the carburetor ID number, a photo of one of the screws, plus measurements I took.

A reply from Quadrajet Power confirmed I was ordering the correct idle mixture screws for my Rochester Quadrajet.

The $10 cost for the pair, shipping included, made this decision super easy.

Thursday, December 20, 2018

Quadrajet Tuning: Adjusting the Idle Mixture Screws


For some of us who own C3 Corvettes equipped with Rochester Quadrajet carburetors, getting them properly adjusted seems to be a difficult task. And at first glance, it appears only a select few know the secret or the magic juju spell required to get a Quadrajet to run right.

I've had professional mechanics attempt to get my 1976 Corvette Stingray to run properly, with mixed results (no pun intended), and I've never been 100% satisfied. From rough idle to hard-starting to extreme gas smell, my car experienced all of those and more.

One "professional," for example, convinced me Quadrajets were trash, so I spent money on a brand new Edelbrock. This was not the solution and that carb was, in my opinion, worse than the factory carburetor.

Eventually, I sent my old and tired Quadrajet to All American Carburetors in Orange Park, Florida, and they remanufactured it. A few weeks later, I had my old carburetor in like-new condition.

The mechanics who did the engine swap reinstalled it and adjusted it a bit so the car would run okay. And it did. My Corvette ran "okay." Call me crazy but I wanted it to run great after all the money I'd spent.

Friday, December 7, 2018

Replacing the Fuel Filter on the Rochester Quadrajet

Where is the Fuel Filter Hiding?

In plain sight, that's where.

And even though that may sound like a dumb question once you know the answer, I know I was left scratching my head many years ago when someone told me that it would be a good idea to replace my Corvette's fuel filter on another '76 Vette I owned back in the early 1980s.

Anyway, the fuel filter resides inside the fuel inlet housing right on the carburetor itself.

GM engineers even added the word FILTER along with an arrow showing the location.

Saturday, August 25, 2018

Building 3" Car Ramps

Three inches is not a lot, but three inches allows me to maneuver and position the low-profile jack I have a lot better, thus allowing me to raise my Corvette without flexing the body as much. If you've ever lifted your Vette from one side, pay attention to the door gaps and you'll see what I'm talking about.

I built four ramps in order to drive the car up on them and keep it level. This also allows better access all around, especially after you jack up the vehicle and have it sitting on jack stands front or back or both.

Since I did not want to break the bank with this project, I purchased inexpensive,  construction-grade lumber. You could build nice ramps from an exotic hardwood, for example, but for my garage, this lower-grade stuff is just fine.