Spark knock during acceleration on incline's

Asked by Jul 28, 2018 at 08:12 PM about the 1985 Chevrolet C/K 20 Scottsdale LB RWD

Question type: Maintenance & Repair

Spark knock during acceleration on

4 Answers


Assuming the engine isn't heavily modified and you're running clean, fresh fuel here's a few things to check off the top of my head. Vefiry you have the correct heat range spark plugs, factory stock make and model is ideal. Make sure carburetor is in proper tune so air to fuel ratio is correct. Check and clean EGR valve, it cools the combustion process and aids drivability. Check and adjust spark timing via distributor, the distibutor advance module (can on side of distributor) may be not functioning correctly (check for a vacuum leak) also the mechanical advance weights and or springs by be out of whack or sticking, repair and replace as required. If all else fails try running high octane fuel and see what happens. Spark knock which is pre-ignition (not to be confused with detonation) can occur when there is alot of carbon deposits in the combustion chambers, a tell tale sign of that is a splatter of black soot after a cold startup that dries to a powdery susbstance. Most of these things are cheap or free to test for someone with a little automotive experience (some research may be required) and a few basic hand tools (SAE wrenches and screwdrivers mostly). I hope this helps some


I posted a reply but it's stuck in Cargurus limbo assumably because it's lengthy =s

1 people found this helpful.

I've had this problem before but with a different vehicle I just can't remember what I did to fix it. I think it has something to do with carburetor thermostat adjustment but I can't remember


The choke thermostat? That you can watch for proper operation easily by starting the vehicle cold, the choke should be closed and then begin to open as the engine warms up and stay fully open until you shut it down and the bi-metallic choke spring cools back down

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C/K 20

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