I actually found a working original style clock in a box of spare parts. It seems to gain about 2 seconds in three minutes. It won't take long for it to get way out of time at that rate. It looks like there is a rocking or sliding switch accessible through a hole in the back, but I have no idea how it works or if you can even adjust it that way. Any thoughts?
P.S. I know the sensible thing would be to buy a replacement quartz unit, but I have this working original so I first want to try that route. Call me crazy.....
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1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.