How do, all? I know there's other threads about ping/spark knock, but I've searched/trolled most of em and am not finding anything that applies I haven't tried.
I have a 79 with a pretty much stock 351m that was (supposedly) rebuilt about 15k miles ago. Had it about 6 months as my daily driver, and it's run like a champ, until last Tuesday.
Cruising into work on the highway at about 55, ironically, I had JUST been thinking how great it seemed to be running that morning, and then I stopped at a red light to make the turn up onto post. As I began to accelerate up the small hill, all the sudden it starts knocking/pinging like crazy. And it's been doing it ever since, despite trying ever suggestion I've come across.
It doesn't make a peep at idle, just purrs like a kitten. If you rev it up somewhat gently, no noise, though if you're out of gear idling and crack the throttle open, it will make one or two sharp "Tink" sounds. On the road, cruising or decellerating, no issues, sounds like normal and runs great. It's only under load, accelerating, it will just make a constant, loud, and fluctuating "tink-ta-tink" sound.
I've replaced the distributor (thinking maybe bad advance mechanism?) and played with the timing till the cows come home. Also changed out the brand new Autolite plugs for some Motorcraft coppers properly gapped, no change.
I just finished rebuilding the carb today (edelbrock 1406 with performer 400 manifold, no EGR/emissions), seems to actually be running a little better (I knew it needed the rebuild), but no change on the pinging.
I've checked for vacuum leaks and sea foamed the crap out of it, even tried the glass of water through a small vac. line, no dice.
Checked for the possibility of an exhaust leak or loose torque converter bolts, all seems well.
Pulled the valvecovers, everything looks new and clean, pushrods are all straight and tight (will rotate but no up and down movement) and ran it abit opened up, everything looked good and made a helluva mess spraying oil from every push rod just fine.
I have a friend who's been playing with old Fords all his life and tends to know what he's talking about, he suggested that possibly the timing chain has stretched or jumped a tooth... but it seems to me that wouldn't that actually retard the timing at the distributor and just make it run like crap, but not ping? Also, seems like a lose chain would cause the timing to jump around, but mine seems rock solid watching it under the timing light.
I'm not ruling out the possibility of a knock/bearing/etc., but wouldn't it also make the noise at idle and especially deceration (i.e. if it was a wrist pin)? Also seems like it would be a bit more 'rythmic' in time with the RPMS, this is very sparatic. And I've tried pulling every individual plug wire, none seem to change or effect the noise much, if at all.
Kind of at my wit's end here, especially with this ole girl being my daily driver. Any helpful insights would certainly be appreciated.