Tach drive coupler is a softer...
Tach drive coupler is a softer bronze material. When removing the drive gear, loosen the coupler with a suitable driver. This tool can be fabricated from sheetmetal thick enough to fill the cross slots snugly. Create a notch to clear the drive gear. While loosening or tightening the coupler, hold the tool steadily to prevent damage to the slots.
A fluctuating dwell angle reading is the first clue that a distributor needs rebuilding. If the distributor shaft bushings have wear in excess of two degrees variation on the meter, the distributor needs a complete rebuild. Shaft and bushing play can be tested with the distributor still in the engine. Remove the cap and check the movement of the shaft. If a dial indicator is not available, insert a feeler gauge into the point gap with the rubbing block on the high point of the cam lobe. Pull and push the shaft toward and away from the rubbing block. Note the amount of change in the point gap. Excess movement is a clear sign of bushing wear. If in doubt, remove and disassemble the distributor. Often, after cleaning away varnish and debris, the shaft play will be even greater.
If a rebuild is necessary, mark the location of the distributor base and the intake manifold. Cap removed, index the rotor by placing the crankshaft damper at the TDC mark for #1 cylinder. Mark the distributor housing where the rotor points toward #1 spark lead. This will enable easier installation of the distributor and provide a firing position for starting the engine. Once the engine starts, you can verify timing with a light, following the procedure in your factory workshop manual.
Carefully remove the tach...
Carefully remove the tach drive coupler and drive gear. Remove the distributor drive gear's pin and the drive gear. Slide the driveshaft out and remove the spring or wave clip that retains the point breaker plate. Measure the height of the upper bushing above the housing bore. Using a suitable bushing driver with an arbor press, carefully remove the two bronze bushings from the housing.
Though not complicated, distributor rebuilding requires care, detail, and cleanliness. The distributor's driveshaft spins the oil pump, which must function flawlessly. Debris that falls into the engine can contaminate the crankcase. If abrasive, debris can circulate and cause internal parts damage. Use a shop vacuum around the distributor's base and the intake manifold before removing or installing the distributor. Cover the distributor opening with a clean rag to prevent debris or hardware from dropping into the engine when the distributor is out.
The ignition distributor, including its advance mechanisms, plays a crucial role in the performance and reliability of a Corvette engine. Adequate spark and timing accuracy determine the ease of startups, acceleration, cruise performance and passing power. When wear exceeds simple tune-up needs like new spark plugs, points, condenser, rotor and cap, a distributor rebuild can restore power and provide years of reliable service.
| Difficulty Index - 3 Wrenches |
| Anyone’s Project: no tools required | 1 Wrench |
| Beginner: basic tools | 2 Wrenches |
| Experienced: special tools | 3 Wrenches |
| Accomplished: special tools and outside help | 4 Wrenches |
| Professionals Only: send this work out | 5 Wrenches |
Upper bushing and its grease...
Upper bushing and its grease cavity show wear and solidified grease. Bushings are durable and need no attention over the distributor's service life. Use of proper greases during assembly will preserve the breaker plate and upper bushing. Align the upper bushing's oil hole and the tach drive gear's notch when fitting the new bushings.
Wear points in these distributors...
Wear points in these distributors are clear. Fortunately, the points, condenser, rotor, breaker plate, driveshaft, shaft bushings, weights and springs, the drive gear, vacuum advance and hardware are still available for this distributor. The tach drive parts are also vulnerable to wear, with parts available in the aftermarket.
Parts like this breaker plate...
Parts like this breaker plate have bearing surfaces and electrical wiring. The bushing on this plate has no appreciable wear. The wire is a ground and shows slight oxidation and corrosion. The corrosion can be eliminated with a quality contact cleaner or baking soda rinse. Driveshafts seldom wear out; however, a replacement shaft is currently available if needed.
Unless the distributor cam...
Unless the distributor cam lobes have bad wear or scratches, the surface can be restored with a polishing buffer and metal polish. This cam must be smooth, or the breaker point's rubbing block will deteriorate quickly, closing the point gap. Take time to restore shafts and running surfaces.
The cam assembly looks like...
The cam assembly looks like new after polishing and cleaning. Hard parts need abrasive cleaning with appropriate soda or glass bead blasting. The breaker plate can be re-plated if necessary, using a zinc electroplating system like the one available from Eastwood Company. Apply these restoration procedures if new parts are not available.
These crucial parts are now...
These crucial parts are now restored. Cost of NOS parts can be high, depending upon demand. By restoring the housing, breaker plate, and cam assembly to perform as new, this Corvette distributor remains authentic and ready for another four decades of service. OEM and NOS parts assure the quality that Delco-Remy built into these components.