1. Clean and tighten the carburetor and intake manifold bolts.
2. Change the breaker points and condenser. Remove the centrifugal weights; clean and lubricate them. Oil the wick inside the distributor and grease the distributor cam.
3. Check the vacuum advance canister with a hand-held vacuum pump.
4. Change spark plugs, fuel filter, and so on.
5. Change engine oil to remove any fuel contamination from short trips, numerous cold starts, and so on.
6. Start the engine; allow it to warm up.
7. With the vacuum canister disconnected and the line plugged, set the point dwell while being cognizant of idle speed. If it's too slow or too fast, adjust it to near the desired specification first.
8. Check the base ignition timing and adjust it if necessary. Raise the engine speed to check the mechanical advance. (The specs for your HEI are in the '75 Pontiac Service Manual.) Reconnect the vacuum advance, and check the rate of advance just off idle. If there's an adjustable vacuum canister, tailor it to the engine's needs. If the position of the distributor must be changed more than 5 degrees, recheck the point dwell with the new timing setting.
9. With the air filter in place on automatic cars, find a helper to hold the brake while the wheels are chocked and adjust the idle mixture screws to achieve the highest rpm. Readjust the curb idle if necessary. You want to have the air filter in place and the transmission in drive to create the pressure drop the engine will see in actual use.
10. Road test the car.
Regarding the timing marks on your engine, it sounds as if the balancer has spun on the elastomer material. A new, quality-brand harmonic balancer will fix the problem.
Fuel Gauge FixMy '69 Firebird originally came with a 350 and now has a '67 400. I have the original fuel tank in the car and my fuel gauge has stopped working. I ran the car until the engine quit and there were still four gallons left in the tank. I replaced the whole pickup unit in the tank and now the fuel gauge only goes to three-quarters full, and it will only pick up 14 of the 18 gallons in the tank. What can I do to get everything working again? Keep up the good work.
Doug
Green Bay, WI
Ray T. Bohacz responds:
To find out what's going on with your gas gauge you will have to remove the tank once again. Once it's securely on the ground, remove the sending unit and then plug it back into the wiring harness. Have a helper watch the fuel gauge in the car, while you move the float through its full range of travel. The gas gauge should read accurately, the position of the float.
From my experience, you either have the sending unit installed in the wrong clock position (it does not take much to do that) and the float is binding on something in the tank, or you were sold the wrong sender/float combination.
The fuel gauge is a very simple circuit; so I feel confident that if you take the time to study what is happening, you will fix it in short order.