daverino Posted October 8, 2011 Report Share Posted October 8, 2011 Hey dudes. So I have a 76' datsun 620 w/ around 220,000 miles on it and engine has been acting a little weird recently. I was driving it up a hill and the engine was making popping sounds and losing power every time I pushed on the gas pedal. When accelerating on flat ground, everything is fine but uphill, the car was dying. also before this happened, the speedometer started acting crazy and spinning all over the place. Not sure if they're related but something is definitely up with my lil' hustler. Any thoughts would be greatly appreciated as to what's going on. Thanks, Dave Quote Link to comment
metalmonkey47 Posted October 8, 2011 Report Share Posted October 8, 2011 Manual? (Thought they were all manual, but just playing safe) Any mods on it? Stock carb? Any recent work done? Quote Link to comment
daverino Posted October 8, 2011 Author Report Share Posted October 8, 2011 Stock Carb, manual 4 speed. only makes sound and loses power in 3rd and 4th gear Quote Link to comment
daverino Posted October 8, 2011 Author Report Share Posted October 8, 2011 re-did the air filter and carb hoses about two months ago due to vacum leak. that's the only work ive done. Quote Link to comment
Str8_69 Posted October 8, 2011 Report Share Posted October 8, 2011 If not EL Dizzy check points, definately check dist cap for fuzz on the electrodes, or possible cracks, check rotor. Quote Link to comment
datzenmike Posted October 8, 2011 Report Share Posted October 8, 2011 Popping sound is usually a backfire through the carb and is quite noticeable. This can be caused by the following... 1/ A bad intake valve seat, damaged or bunt valve or possibly not fully closing because the valve clearance is not set. Check and set the valve lash to proper spec. A leak down test will confirm a hissing sound from a leaking valve. If the sound is from the carb an intake valve or seat is bad. If from the tail pipe its an exhaust valve. 2/ A blown head gasket between two adjacent cylinders. A compression test will sometimes show two adjacent cylinders with low values. A small leak may not be big enough to show up. 3/ Spark jumping to another wire and firing the wrong cylinder. Inspect all wires and ends, cap and rotor for obvious damage. Clean with WD-40 and a rag to remove grease and dirt. Look for carbon tracking which looks like a scratch or burnt path where the spark has found a path to arc across. If in doubt replace them all. Quote Link to comment
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