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Re: Knocking sound under load, obove 3K rpm Posted by Landjet [Email] ![]() ![]() ![]() In Reply to: Re: Knocking sound under load, obove 3K rpm, nuysSAAB ![]() |
If your distributor has a retard servo for when you have boost, then make sure that it is retarding the the spark. This can be tested by applying low pressure from a bike pump, or mityvac to the servo while the engine is at idle. Watch the timing light readings to see that the timing is indeed being retarded when pressure is on the servo. If it isn't, then you are knocking from too much advance under boost. Note how much retard you get, and compare it to the specs.
You should also run some Techron concentrate through a couple of tanks of gas. Use the "concentrate". It is remarkable stuff to get rid of carbon buildup that may be producing hot spots that are causing the knocking.
If this doesn't do it, then you might get a stethoscope tool from Sears, and try to trace the sound at idle.
posted by 152.163.10...
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