Last Place

For the longest, I've battled spark knock. The spark knocking could be heard under any acceleration, no matter if it was downhill, uphill, level ground, hot or cold. I've tried using higher octane fuel, different plugs, chemical cleaners, etc.

Today I was examining the plug wires, which need to be changed, and I noticed that one of the wires going to the dist. cap was loose(not pused down all the way). Not only was it loose, the inside of the terminal was completed rusted. I cutt off this rusted terminal and crimped on a new terminal.

The engine never seemed to have a skip, but this had to be causing me some trouble. If nothing else, it was making the coil work hard.

I haven't test drove it yet, but was curious as to if this could cause the spark knock?

1979toy

No it will not.

Try disconnecting and plugging your vacuum advance and see if the problem goes away. If you do not have a vacuum advance now you need to back the timing off 2 degrees at a time until the knock goes away.

Last Place

You're right, knock still there. At the least maybe I'll get better mpg :lol:

So if I disconnect the vacuum advance and it goes away, what do I do then? Just plug the advance line and drive without it? What effect will that have on power and fue3l economy?

Thanks! :seeya

Larry B.

You don't say wheather you have an HEI or point type distributor but both have mechanical advance weights .. The center shaft that the weights are part of must move freely a few degrees by hand and snap back with the spring attatched to the weights. If not the center shaft has frozen and need to be freed up. This will not allow the mechanical advance to back off when the rpm's slow down. You may have to remove the distributor to do the job depending... Also the is a bushing that limits the total advance (on the pin that rides in a obound slot in the mainshaft. If this bushing is missing, which by the way is very common the then timing will overadvance. The are several spring and bushing kits available at most auo parts place in the speed section that allow you to customize you distributor for todays agas or you combination of mods or whatever. The instruvtions give you starting points but it's really a trial and error thing. It works very well when you find that sweet spot . The weight that come in the kit are never very good. The stock one usually work better but make sure they are not worn at the holes. Just go to a seed shop... They will expain the whole thing.


[Modified by bluevetteman, 7:21 AM 3/25/2004]


[Modified by bluevetteman, 7:23 AM 3/25/2004]

SpyderD

"So if I disconnect the vacuum advance and it goes away, what do I do then? Just plug the advance line and drive without it? What effect will that have on power and fue3l economy?"

If it is the vacuum advance - See if you have an adjustable vacuum advance, Vacuum advance on these units are limited by a "limiter plate" so you only get as much vacuum advance as you need before you ping. You can purchase an adjustable one as well, they aren't that expensive ($25 or so).
As the previous guy said - tuning it is a trial and error process.