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1968 Bel Air Diagnostic Test - Playing Doctor

Sneak a Peek Under the Hood and Between the Framerails

Mike Harrington Nov 2, 2006
Sucp_0607_diagnostic_01_z 1968_chevy_bel_air Front_view_hood_up 2/35

There you are, standing in the driveway, staring into the garage at your first new/old car. What a deal. You picked it up for only $1,900 and it runs, too! If you're anything like the typical car guy, images flash through your mind of cruising on a warm summer night with one hand on the wheel and the other doing the "Orangutan Hang" out the window. Sure, it's rough around the edges, but what can you expect from a $1,900 car, but hey, it's yours and you can't wait to get in and cruise it.

Before jumping in and running full throttle down the highway, there are some mechanical items begging for attention before any action is performed-sorry to burst the bubble of imagination there. Indeed, basic diagnostic evaluations can save you a world of hurt and even some money. There are also a few cool tools that should be added to any automotive collection. For those tools, we turned to Equus for help, (but more on that later).

Sucp_0607_diagnostic_02_z 1968_chevy_bel_air Front_wheel_and_jack 3/35

Before we crack open the hood, let's first get to the dirty job of crawling around the underside. It's time to lift it up, put it on stands, and pull off the wheels.

Back when I was in high school, I was saving every nickel and dime to buy my first car. My grandfather saw me working hard and stocking away my money, and decided to help me out with the automobile situation. He did so by handing me the keys to his '73 Camaro! How's that for a 17-year-old kid in school? My dad, however, wasn't so thrilled. About a year later, the small-block started running rough, and shook like a dog passin' peach pits. I was perplexed as to how I should handle it. I had no mechanical skills, and no idea how to check the timing, compression, vacuum, or anything else for that matter. My father, being a "Ford man," never did help me spin wrenches on the Camaro. Gradually, the car got worse, and eventually stopped running all together. Giving in to frustration, I eventually sold the Camaro for $400, and I never saw it again-a decision I will always regret.

For some of the new guys just getting into this lifestyle/hobby, there is nothing like looking back with regret over selling a car-when you didn't have to-due to the lack of mechanical skills. For you fellas who have just sent your last kid off to college, and are looking to recapture your youth and buy the car you have always dreamt about, we hope that getting back to basics helps you achieve your automotive pursuits.

Sucp_0607_diagnostic_06_z 1968_chevy_bel_air Tire_tread 4/35

While we've got the wheel off, take a closer look at the tread. Look at your tires and check for uneven wear patterns and tread depth. Uneven wear patterns can be indicative of misaligned steering. Apparently, the previous owner put on a new set of tires-hoorah for us! For the time being, that's one less thing to worry about.

Sucp_0607_diagnostic_10_z 1968_chevy_bel_air Drum_brake_cover_off 5/35

Now let's pull the drums off all four corners and make a visual inspection of the drum lining. Check the drums for any deep wear patterns or cracks; in our case, the drums were just fine.

Sucp_0607_diagnostic_03_z 1968_chevy_bel_air Wheel_cylinder 6/35

After checking the drums, let's take a look at the brake shoes and wheel cylinders. Inspect the wheel cylinders to make sure there is no leaking fluid and all the seals are in order. Also, check the backing plates. If any brake fluid is present it'll usually translate into a greasy, wet mess on the backside of the backing plate and surrounding suspension components; replace them immediately. Wheel cylinders are inexpensive to replace.

Sucp_0607_diagnostic_07_z 1968_chevy_bel_air Wheel_bearing 7/35

Next up on the list: let's pull the wheel hubs off and check the wheel bearings. Make sure they have plenty of grease and repack them if necessary. True story: I once had to spend the night in a tiny out-of-state town on account of dried-up wheel bearings that had gone bad. The new bearings arrived the next day via overnight delivery (not cheap). If you hear a metallic chirping noise from your wheels or vibrations, stop and take a look for safety's sake.

Sucp_0607_diagnostic_11_z 1968_chevy_bel_air Spindle 8/35

A quick visual inspection of the spindle is also on the list. Look for any worn or shaved spots on the spindle where the bearings sit.

Sucp_0607_diagnostic_04_z 1968_chevy_bel_air Clean_drum_brake 9/35

After looking the brakes over, everything checked out in our favor. Once everything is put back into place, a quick dowsing of brake cleaning solvent should be the icing on the cake.

Sucp_0607_diagnostic_08_z 1968_chevy_bel_air Front_suspension 10/35

It made perfect sense to inspect the entire underside of the vehicle, since the car was up on stands. Once again, we were pleasantly surprised to find that the frontend had recently been rebuilt. All the bushings were in top shape, the chassis was lubed, the steering box was new, and some of the control arms had been replaced. We did, however, notice a leaking shock, so we put that on the list of must do's. Besides that shock, the underside of the car was in excellent, rust-free condition, and the exhaust looked fairly new! This budget vehicle is starting to look better and better.

Sucp_0607_diagnostic_12_z 1968_chevy_bel_air Oil_filter 11/35

While under the car, you might as well change the oil, right? After all, we have no idea when the last oil change was. If you're anything like me, I have lost about three oil filter wrenches in the last two years. This time around, a K&N filter is on the list for use. Why K&N? Not only do they make some of the best filters around, they also have a 1-inch nut attached to the bottom of the filter saving me from having to hunt for my missing filter wrench.

Sucp_0607_diagnostic_05_z 1968_chevy_bel_air Vacuum_bleeder 12/35

Here is one of the must-have tools from Equus we spoke of earlier. This hand-held vacuum brake bleeding kit is a time saver. Just pump the handle to create vacuum on the brake line, and then turn the bleeder valve. What used to be a two-man job of brake bleeding can be turned into a one-man show. It might be a very good idea to first bleed the master cylinder then bleed the lines, but that usually involves removing it and bleeding it on the bench. There is no way to determine the age of the brake fluid in your car. For all we know, it could be from 1968. It's time to drain and replace all of it; this vacuum bleeder is a must. Remember to start at the wheel farthest from the master cylinder and then work your way around. Repeat if needed.

Sucp_0607_diagnostic_09_z 1968_chevy_bel_air Repair_manual 13/35

Now that we are done crawling around on our backs, it time to climb up top and under the hood. Before starting any tuning and adjusting, having a reference manual or book with all the specs and diagrams is a big help. Tony Kelly saved the day and let me borrow his motors manual for the weekend tune-up of this 327 small-block.

Sucp_0607_diagnostic_14_z 1968_chevy_bel_air Engine 14/35

And here is the stock 327. It sure isn't pretty to look at, that's for sure. But "pretty" doesn't get us down the road, either. It's time for a quick visual inspection of the engine.

Sucp_0607_diagnostic_15_z 1968_chevy_bel_air Coolant_puddles 15/35

Right away, I noticed pools of radiator coolant on the intake manifold. It looked like a faulty thermostat-housing gasket was the culprit-an easy fix and an inexpensive part. Looks like we've got another trip to make to the local parts store.

Sucp_0607_diagnostic_16_z 1968_chevy_bel_air Radiator_cap 16/35

Before draining the radiator and flushing it, take a look at the condition of the coolant inside, it may have some telltale signs in it.

Sucp_0607_diagnostic_17_z 1968_chevy_bel_air Coolant 17/35

You want to look for any oil that may be present in the cooling system, which could be a bad sign that a blown head gasket is releasing oil into the cooling system and vice versa. In this case, the coolant was as green as the Incredible Hulk, which is just what we want.

Sucp_0607_diagnostic_18_z 1968_chevy_bel_air Dipstick 18/35

Another way to check for a leaking head gasket is the dipstick. If the oil appears to have a milky look to it, you could be in for some more repair work. Just like the coolant, the engine oil was fine.

Sucp_0607_diagnostic_19_z 1968_chevy_bel_air Antifreeze_and_flush_kit 19/35

Let's back flush the radiator. Since the car has only been in my possession for a week there is no way to know if it has ever been done. The radiator appeared to be in great shape, so there was no need remove it or take it to a radiator shop for hot tanking or replacing. While at the auto parts store, we picked up a basic back flush kit from Prestone.

Sucp_0607_diagnostic_20_z 1968_chevy_bel_air Back_flushing 20/35

Back flushing the radiator is pretty straightforward and simple. Just follow the instructions on the back flush kit and you will have no problems. This would also be a good time to replace that thermostat-housing gasket.

Sucp_0607_diagnostic_21_z 1968_chevy_bel_air Filling_radiator 21/35

Lastly, fill her up with a 50/50 mix of anti-freeze and water.

Sucp_0607_diagnostic_22_z 1968_chevy_bel_air Engine_bay_cleaning 22/35

Since the driveway is a big mess, let's make it messier, shall we? One of the best ways to make a diagnostic check on the engine is to thoroughly clean the engine bay. How does that help? Well it makes it easier to spot any of those mysterious oil leaks that seem to plague old engines. We used a biodegradable cleaner on our engine bay. Some of the more caustic cleaners, running down the gutters, might not make the neighbors happy, not to mention, the EPA.

Sucp_0607_diagnostic_23_z 1968_chevy_bel_air Valvetrain 23/35

After the engine was cleaned, we spotted a small leak coming from one of the valve cover gaskets. We pulled off the valve covers and had a look. The valvetrain looked to be in great shape, no gummy residue build up was present anywhere under the covers.

Sucp_0607_diagnostic_24_z 1968_chevy_bel_air Gasket 24/35

It just so happened there was a set of Mr. Gasket valve cover gaskets collecting dust in the garage. So on they went.

Sucp_0607_diagnostic_26_z 1968_chevy_bel_air Gasket_sealer 25/35

After scraping the last of the old gasket sealer off the heads, a thin layer of silicone sealant is spread on the new gaskets; no need to go overboard with the silicone sealer, a little dab'll do ya'.

Sucp_0607_diagnostic_28_z 1968_chevy_bel_air Valve_cover_gasket 26/35

Try 'em on for size. Batten down the valve covers, and that's one more task to scratch off the list.

Sucp_0607_diagnostic_29_z 1968_chevy_bel_air Timing_light 27/35

This next tool has got to be the most useful of the bunch-a four-in-one pro timing light from Equus. When the engine is not running, simply hook it up like any regular timing light and voltmeter to obtain an accurate reading of the battery's current strength.

Sucp_0607_diagnostic_30_z 1968_chevy_bel_air Timing_light_strobe 28/35

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 29/35

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 30/35

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 31/35

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 32/35

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 33/35

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 34/35

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 35/35

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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