1968 Bel Air Diagnostic Test - Playing Doctor

Sneak a Peek Under the Hood and Between the Framerails

Mike Harrington Nov 2, 2006 0 Comment(s)
Sucp_0607_diagnostic_30_z 1968_chevy_bel_air Timing_light_strobe 2/35

Turn the engine on and press the strobe button; now you can check the timing of the engine.

Sucp_0607_diagnostic_31_z 1968_chevy_bel_air Timing_marks 3/35

You can see in the picture that the timing marks are a near-perfect match. It would seem the previous owner did a decent job at keeping this engine in peak shape.

Sucp_0607_diagnostic_32_z 1968_chevy_bel_air Tachometer 4/35

Press the function button, and it is now a tachometer. The engine rpm was a bit on the high side, so a twist of the idle screw on the carburetor solved that problem. And we brought the idle back down to 600 rpm at operating temperature.

Sucp_0607_diagnostic_33_z 1968_chevy_bel_air Dwell_angle 5/35

This tool just gets better. Press the function button again and it will show the dwell angle. Refer to the manual for the proper dwell angle if you have a distributor with points.

Sucp_0607_diagnostic_34_z 1968_chevy_bel_air Timing_light_functions 6/35

OK, this is what comes on this timing light.
*Battery Voltage mode
*Alternator voltage/tachometer
*Dwell meter
*And yes, it's a timing light, too.

Sucp_0607_diagnostic_35_z 1968_chevy_bel_air Compression_tester 7/35

Another must-have diagnostic tool from Equus is a compression tester. Testing the compression of each cylinder is the best way to diagnose the inside of the engine. Whether it be piston rings or valvesprings, this tool is invaluable.

Sucp_0607_diagnostic_38_z 1968_chevy_bel_air Compression_testing 8/35

Before doing any testing, follow the accompanying instructions and all safety guidelines closely when using this or any diagnostic tool. Disable the ignition system, and turn the engine over five times with the compression tester threaded into the spark plug hole. Test each cylinder the same way and record the results for each one. Take the lowest reading number and the highest; if they are within 80 percent of each other, compression is acceptable. There is a long list of instructions accompanying this tool and we just skimmed the surface of its functions. Like we said, read the instructions before during and after its use.

Sucp_0607_diagnostic_36_z 1968_chevy_bel_air Engine_vacuum_and_fuel_pressure 9/35

Last on our diagnostic list is to test the engine vacuum and fuel pressure. Once again, a must-have tool from Equus aids us in the process. We hate to keep beating a dead horse here, but refer to the included instruction manual on the operation of this tool. As it turns out, the vacuum and fuel pressure on this 327 small-block is running right at what the motors manual says it should be. But it was missing a fuel filter, tsk, tsk, tsk. We took care of that in a hurry. When you're at the local parts store, getting all the necessary stuff for your engine, you should be able to find all the tools, gaskets, and filters that we mentioned sitting on the shelf. If not, go to a better parts store.

Believe it or not, this '68 Chevy is in reasonably good mechanical shape. The only things that need to soon be addressed are the carburetor and an update on the ignition system. Other than that, for a low-dollar car, it can be driven around as it slowly gets fixed up dollar-by-dollar, and month-to-month. Armed with the knowledge that your vehicle is reliable, upgrading other items such as brakes, suspension, interior, and bodywork are easier to justify rather than an emergency engine build. So have some fun, the sky is the limit on which direction to go from here.


Equus Products
17291 Mount Herman St., Dept. SC
Fountain Valley, CA 92708

K&N Engineering
P.O. Box 1329
1455 Citrus St., Dept. SC
Riverside, CA 92502
Phone: (800) 858-3333 or (951) 826-4000

Mr. Gasket Company
10601 Memphis Ave. #12, Dept. SC
Cleveland, OH 44144


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