I took my beloved '74 Duster for a ride last night and wanted to feel how strong the old and tired Slant still was. I drove to a not very steep (although steep) road, and the car just made a great effort to keep moving while the engine kept making a "rattle" sound (not sure of the right term in english, but it is the sound made when a high compression engine is fueled with low octane gas... knocking perhaps?).

Earlier yesterday I replaced the stock spark plugs with extra-long electrodes Autolite 985... I think it had nothing to do with it.

How can I correct the problem before the major repair needed?... want to keep driving it but still saving some $$$ for the overhaul.

Thanks,

Ed

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My other car is... another DUSTER!!! .·.

Was the sound at full throttle?
If it was not, you can try to adjust the vacuum can on the distributor, for less advance.
If it was, adjust the distributor for less adv.
Or both, if you need to.
You can try to run up that hill with the vacuum hose disconnected, and see if that helps...

That's a very good question Rust... , I believe so, but not sure... the car was having a bad time climbing that hill, so I ass-u-me it was at full throttle... But anyways, how do I adjust the vaccum can, remember I'm still a dope here. I noticed it has some sort of hex edge, is it for adjustment?

Ed

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My other car is... another DUSTER!!! .·.

You need a small hex-wrench that I dont remember the name of.
You take off the hose, and insert the tool in the hose-nipple-thing on the can.
I think you will find a better explanation if you do a search...
But if you were at full throttle, the vacuum is probably to low to adjust timing, so try to turn the distributor a few degrees. And try without the hose connected first, to be sure it isn´t the vacuum part that makes it knock.

Ok Rust, I'll try to follow your instructions. You know, everything related to timing has been one of the most difficult parts of my learning here. When I checked it and adjusted (or missadjusted) a couple of weeks ago due to an excessive gas consumption, the engine ended up stalling all the time, running erratically, etc... it was a real mess, and continued to burn gas as if there was no tomorrow... had to take it back to where it was before.
I don't know why I just don't quite understand spark advance timing and related stuff. Still think my car has an incorrect timing but for me it is impossible to know it yet.

Ed

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My other car is... another DUSTER!!! .·.

STOP, don't adjust the vacuum advance until you get the basic timing sorted out. The vacuum cans do not go out of adjustment; the only reason to adjust them is to change the amount of advance they give. That may or may not be necessary -- first the engine has to be timed to spec and the mechanical advance system has to be working properly. How did you set your timing?

Yes listen to Dan, and look at the mechanical part first.
Sorry about that

I used a timing light gun, lose the visible adjusting screw in the base of the distribuitor and checked the mark in the damper... it was at around 10:00 (in a clock), I thought it was far from being right. (of course I think it was stupid on me to ASS-U-ME that with no real info... the sticker under the hood is long lost), I assume that because it was far out of the timing plate that is stuck in the block. I moved the timming until the mark appeared inside the plate... the thing is that the most adjust I could make was 0º, it didn't allow me to go any further; so I set it at 5º BTDC. The engine didn't like the change... believe me. The only good thing then was a very nice "hollow" sound coming out of the exhaust pipe while depressing the accelerator a little... don't know why.

As you can see it was some sort of experiment with no background... sorry teacher

I ended up readjusting timing back to the "original" setting, which by the way was the opposite site of the screw slot in the base (oposite to 0º).

I hope you understand what I just described, in the preview of this post I couldn't quite understand myself... what do you think?

Ed

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My other car is... another DUSTER!!! .·.

Yeah? Which spark plug wire did you clip onto?

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

According to the instructions of the gun, I connected the spring adaptor to the #1 plug... is that right?

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My other car is... another DUSTER!!! .·.

the number one plug wire, yes.

Yes, of course to the wire...

After some research and some PM's, I am starting to believe that my damper slipped... got to check it.

Ed

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My other car is... another DUSTER!!! .·.

To set the timing accurately, the vacuum advance hose must be disconnected and plugged, the engine's slow idle speed must be correct, the vibration damper must not have slipped, and the distributor's mechanical advance system must be working correctly (weights not stuck, springs not broken).

5° BTDC is a good starting point.

Remember, when the engine is tired, it will ingest a lot of oil, and this greatly reduces the octane rating of the fuel. Not only that, but burning oil creates carbon in the combustion chambers. Both of these things greatly worsen the tendency to ping. On top of that, the reports I hear are that Pemex gasoline is not very good quality (maybe getting better?). So, this may just be one more indication that your engine is a tired pony.

If I suspect a bad damper I usually just run a line of paint across the two pieces across the rubber and drive it for awhile. if the paint line doesnt line up with itself anymore the damper is bad. You probably dont have that option. As has been no doubt shared with you privately the TDC mark can be checked by setting #1 cyl (the one at the front of the engine) to TDC on compression.

Since you dont know if the dist. shaft is indexed right (maybe someone has had it out) just whip off your valve cover and rotate the engine until you can feel the piston coming up (gently insert the dipstick into the sparkplug hole to feel it) and watch the valves. If they stay closed as the piston comes up, you are coming up on the power stroke. Wiggle the fan back and forth until you are sure that the piston is at the very top. Then, look at your dist. The rotor should be pointing to the #1 dist tower (put the cap on for a sec to check) and if it is, turn the dist body until the points just start to close. Thatll set up your dist. Then look at the TDC mark on the crank pulley and see where it is. It should point very close to the center mark on your degree plate.

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

Pemex gas is ok now, but I feed my baby Magna (89 octane) and not Premium(93). I was not aware of the octane situation, thought that having a tired engine, compression was to low to need higher octane. Besides, it never pinged or knocked before, until I forced last night in the steep road.

I'll check all the factors you are pointing out before attempting to adjust timing again.

Thanks a lot.

Ed

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My other car is... another DUSTER!!! .·.