engine and drivetrain Update on my jumping tach woes...

[Guest Anonymous]

I pulled the timing back last night to get rid of the pinging, but the tach is still jumping around. Hooked up a dwell meter/tach, and discovered that my dwell is jumping around also: if I'm reading the thing properly, it's centered on about 44 degrees (too little, according to the manual, but the point gap is OK), but it jumps from 40 to 60 degrees intermittently. The tach function of the gauge centered on about 800 rpm, but it was fluttering like my dash gauge, occasionally bouncing down to 100-200 rpm, correcting up over 1000, then back down. The engine was doing its usual not-quite-butter-smooth-but-not-bad idle at this point (warm engine), and it didn't seem to be "searching" as much as the meter indicated.

In other news, I noticed that my valves are a bit noisy (I think that's it). Prolly ought to adjust 'em this weekend, though I suppose that's unrelated to the other issues.

Thanks for your input...

-Dave

Colorado '71, totally stock engine

[Guest Anonymous]

steady on dwell meter...

[Guest Anonymous]

(nt)

[Guest Anonymous]

First, check the screw that secures the condensor to the distributor housing; if it's loose, it can cause all sorts of grounding problems. Next, check the little insulated plug where the condensor wire (on the outside) connects to the points (on the inside). Next, try changing out the condensor.

Have a safe trip to Austin. Molly and I will be there in spirit.

David Roach

"Molly" (Inka 1973 2002)

"Elmo" (Diamondschwartz 1991 325ix)

[Guest Anonymous]

(nt)

[Guest Anonymous]

(nt)

[Guest Anonymous]

...i.e., in a horizontal or vertical axis with regard to the shaft. There's some rotational play, but I've been told that's normal. I'll check again when I swap the condenser over lunch.

-Dave

[Guest Anonymous]

That can cause a bit of trouble if it is dry.

[Guest Anonymous]

Something else to check at lunch. Hope I get to eat! :-)

-Dave

[Guest Anonymous]

(nt)

[Guest Anonymous]

pad under the rotor. The distributor prolly gets the least amount of maintenance of any item on the car, sorry to say. Both the lobes of the cam, as Neil mentions, and the pad under the rotor, need fed at every oil change.(in my humble but often accurate opinion :-)

[Guest Anonymous]

Swapped in the good used condenser over lunch, put a couple of drops of light oil on the distributor felt and a drop on the cam (I didn't have any dielectric grease), and saw no change in the jumpy tach.

I did notice that I was mistaken about the distributor play: There is no play "horizontally" (at right angles to the shaft), but when I grab the end of the shaft and pull up, there is a little play (a couple of millimeters). Does this help the diagnosis?

-Dave

[Guest Anonymous]

you said you are hearing noises in the valve train.

When you get the valve cover off make sure you check the timing chain for wear.

A worn slack chain will make noise and put the timing and the dwell all over the guage.

It's probably a combination of a worn dist. and worn chain

[Guest Anonymous]

Sorry -- no offense intended. I'm kind of a neophyte to engine internals, so what am I looking for when I check for chain wear? And why would it be worn out after just 126k miles? I thought chains were supposed to be good long past that.

But the important question: Would I do any harm or run into trouble driving this thing 1500 miles to Texas and back in a week?

[Guest Anonymous]

(nt)