Why does the distributor modulator keep burning out?
The 1964 Chevy El Camino’s Distributor was originally equipped with a Breaker Points & Condenser ignition system. If the points are not adjusted properly they will wear out prematurely. The most common cause for the points burning out is caused by too wide a gap that creates excessive arching.
Dwell Angle
Dwell angle is the amount of time (measured in degrees of distributor cam rotation) that the contact points remain closed. Initial point gap (0.019 in.) determines dwell angle. If the points are set too wide they open gradually and dwell angle (the time they remain closed) is small. This wide gap causes excessive arcing at the points and, because of this, point burning. This small dwell doesn’t give the coil sufficient time to build up maximum energy and so coil output decreases. If the points are set too close, the dwell is increased but the points may bounce at higher speeds and the idle becomes rough and starting is made harder. The wider the point opening, the smaller the dwell and the smaller the gap, the larger the dwell. Adjusting the dwell by making the initial point gap setting with a feeler gauge is sufficient to get the car started but a finer adjustment should be made. A dwell meter is needed to check the adjustment. I suggest this Dwell Tachometer.
Dwell Angle Adjustment
- Run the engine to normal operating temperatures and then let it idle.
2. Raise the adjusting window on the distributor cap and insert a 1/8 in. Allen wrench into the adjusting screw.
3. Turn the adjusting screw until the specified dwell angle is obtained on the dwell meter.
NOTE
The HEI (High Energy Ignition) system used on some 1974 and all 1975 models requires no maintenance other than checking the condition of the cap and wires. There are no points to wear out or adjust
Breaker Points Ignition
Point alignment is preset at the factory and requires no adjustment. Point sets using the push-in type wiring terminal should be used on those distributors equipped with an R.F.I. (radio frequency interference) shield (1970–74). Points using a lockscrew type terminal may short out due to the shield contacting the screw.
- Remove the distributor cap.
- Remove the rotor.
- If so equipped, remove the 2-piece R.F.I. shield.
- Loosen the two mounting screws and slide the contact point set from the breaker plate.
- Remove the primary and condenser leads from the terminal.
- Loosen the condenser bracket screw and slide the condenser from the bracket.
- Install the new point set and condenser and then tighten the mounting screws.
- Then Install the wires to the terminal so that they will not interfere with the cap, weight base, or breaker advance plate. Install the half of the R.F.I. shield which covers the points first.
- Using a 1/8 in. Allen wrench, make an initial point setting of 0.019 in.
- The cam lubricator (if so equipped) must be replaced after 12 months or 12,000 miles. The end of the lubricator should be adjusted to just touch the cam lobes. Additional grease should not be applied to the lubricator.
- Start the engine and check the point dwell and the ignition timing.