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Obviously, something changed dramatically. You would have to shave the head significantly to get enough of a boost in compression to cause a dramatic increase in pinging, so that's not a likely cause.
Without a manual here I'll guess that a '79 did not have a knock sensor, so that rules that out.
Looking at things that cause knock (pinging), three primary causes come to mind - an overly lean mixture, overadvanced spark timing, and high ambient (intake charge) and engine temperatures. A less common cause is carbon deposits in the chamber, but since you just had the head redone I doubt that's a cause. So what has changed relative to mixture, timing, and temperatures? Consider:
- is there a vacuum leak anywhere, causing a lean mixture? Pull the plugs and look at them. A bad vacuum leak will have you using more throttle, and gas mileage will suffer.
- you changed injectors and a fuel pump. Are you sure enough fuel is being delivered?
- you probably pulled the distributor when the head came off. Is it re-installed correctly, AND is your timing correct? Is the cam properly timed, relative to the intermediate shaft and crankshaft?
- is your coolant temp showing a normal indication? Is there a chance there are air pockets in your cylinder head? Does the thermostat open at the correct temp?
Last thought is the gas itself. Are you in a geographical area where the gasoline formulation recently changed? Have you tried changing brands of gas, or gas stations? (You can never be sure about what off-brand gas dealers pump.)
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