Is it possible my dizzy springs are old/tired?

[Gogar]

Car: 1983SC. Distributor with both vacuum advance and retard.

I've noticed over the past 1K miles a knocking (similar to detonation) sound when I'm at LOW rpms with load. If I'm at 2K rpm in 2nd and nail it, I can make the sound happen.

Worse when the car is hot,

No problems at all with light load, or anytime above about 4K rpm.

My (no vacuum) advance was set to spec (25 degrees at 4K rpm),

Which would bring it to about 5 BTDC at idle, and about TDC (I think) with vacuum.

I can make everything better if I reduce my advance to 20degrees or less,

which brings my total (with vacuum) advance to around 25,

but that's no fun.

Of course, neither is detonation.


Is it possible my distributor springs are 'tired', allowing too much advance too soon?

I do lube under the felt often, but I have never opened it up and looked around.

[Scott R]

If you want to try mine we can swap it in, it's a fresh rebuild. Would give me a chance to get those tools from you.

But yes, I had some bad timing problems as well, timing would walk, knocking, lag. I used that thread that Goonter did and found the internals on mine were a disaster. The plastic keepers for the springs were gone, springs were just hanging there, thing was bone dry inside and the advance plate was stuck.

I bet if I had cleaned it a few times, maybe oiled it, it would have saved me the cost of a rebuild.

[enjefriy]

Have u changed anythin in that passed 1k. I hav found that spark plugs play an important role in ignition timing. So chk them out too. Does this only happen under load. Free reving will not create similar symtoms

[Gogar]

Thank you guys. Scott, I may take you up on that.

enjefriy,

The knocking sound caused me concern,

Since it started I have installed Carrera tensioners (needed to do it anyway.) No change.

I have messed with timing a bit and got a full fresh tank of 91 and installed a fresh set of plugs. No change.

[Eagledriver]

Knocking sound is a misnomer. The sound from detonation is a rattle/pinging sound. At Denver with 91 octane I doubt you could get detonation even if your timing is off. Maybe get someone else to listen to it to get a second opinion.

-Andy

[Gogar]

I showed off my new sound to my mech, and he diagnosed it as detonation, so that's where I'm going to start, with the timing and making sure my ignition stuff is healthy.

I agree that I 'shouldn't' get detonation at 25 degrees advance with 91 but it's not at the top of the range. If my springs are shot or broken, then wouldn't it advance too much in the middle of the curve and detonate in the middle RPMS?

Thank you

[stlrj]

Has the mixture been tampered?

[Gogar]

Idle mixture is right on the money, about .8%

[jtfreels]

I'll be interested to here how this goes Jeremy. My 82 has exhibited this same symptom for a while.
I can make it go away by enriching the mixture a bit, and yeah it stayed the same over a plug change.

Jay

[Gunter]

Goonter?
Hm................

I'll replay the same old record:

Distributors are the most neglected item in an engine.
Amazing they actually live as long as they do.

Even though you lube under the felt, the bearing for the trigger plate gums up and freezes.

Try this easy DIY:

Distributor service (Clean and lube) real easy without removing the pinion gear! - Pelican Parts Technical BBS

Your distributor will love it.
On the '80-'83, I suggest you disconnect and plug the retard vacuum but leave everything else connected like OX sensor etc.

After the distributor service, with vac retard disconnected and plugged, set the timing the usual 5 deg BTDC @ ~900 RPM and see where the Stroscope shows timing @ 5k RPM.

Or set the timing at ~25 deg @ 5k RPM and let the timing fall where it may at idle.

[Scott R]

Originally Posted by Gunter

Goonter?
Hm................

I'll replay the same old record:

Distributors are the most neglected item in an engine.
Amazing they actually live as long as they do.

Even though you lube under the felt, the bearing for the trigger plate gums up and freezes.

Try this easy DIY:

Distributor service (Clean and lube) real easy without removing the pinion gear! - Pelican Parts Technical BBS

Your distributor will love it.


On the '80-'83, I suggest you disconnect and plug the retard vacuum but leave everything else connected like OX sensor etc.

After the distributor service, with vac retard disconnected and plugged, set the timing the usual 5 deg BTDC @ ~900 RPM and see where the Stroscope shows timing @ 5k RPM.

Or set the timing at ~25 deg @ 5k RPM and let the timing fall where it may at idle.

Sorry about that.

[stlrj]

Originally Posted by Gunter

Your distributor will love it.
On the '80-'83, I suggest you disconnect and plug the retard vacuum but leave everything else connected like OX sensor etc.

After the distributor service, with vac retard disconnected and plugged, set the timing the usual 5 deg BTDC @ ~900 RPM and see where the Stroscope shows timing @ 5k RPM.

Or set the timing at ~25 deg @ 5k RPM and let the timing fall where it may at idle.

Unfortunately, here in the US, most states require smog inspections and what you suggest is not legal. In addition, eliminating the retard would actually degrade performance and throttle response by eliminating the instantaneous tip-in advance the moment the retard vacuum disappears at the slightest crack of the throttle.


Cheers,

Joe

[Gogar]

Originally Posted by stlrj

Unfortunately, here in the US, most states require smog inspections and what you suggest is not legal.
Cheers,

Joe

Understood, but last time I went to get my tag the guy had a hard time even finding the engine, so I'd take my chances with the concept that he would discover the vacuum retard line was unplugged.

[Flieger]

Originally Posted by Gunter

Goonter?
Hm................

"Ah, Günter Wendt.

I wonder where Goonter went? "
- (Tom Hanks from Apollo 13)

Incidentally, Günter Wendt died just a couple weeks ago. The "Pad Fuhrer" responsible for seeing off the Mercury 7, Apollo crews, and Space Shuttle jockies.