Jandk

Help....

last week I had to fill some 95 Octane in the tank (15 litres), pining became present, I drove carefull thinking the low octane was the reason. Arriving at my destination I filled it up with 99 Octane, and added some octane booster try compensate for the leftovers of the lower octane. After driving around 20 km it still pinged. When at home I just left the old car as I had no time to check it.
Today was the first drive since last weekend, and before I drove I checked the timing just to see if anything had moved, now looking back, I am very sure the timing according to the timing light was arround way on the wrong side of the 0 mark. I adjusted it to 6 degrees initial, gave it some throttle a few times and had it settle and checked initial a few times (no difference), made some light checking of vacuumlines, and everything looked fine. I drove, and it was still a pain to drive, felt fresh and powerfull, but easy to get ping also when setting of from full stop. At home again I pulled the vacuumcanister and plugged the line and made a testdrive, NO CHANGE. I then checked timing, and the timing mark was GONE, or at least even furher away from where it should be.
I removed the sparkplugs and distr cap, and sadly I noticed I had a hard time making cyl#1 match distr #1 wire and together with this the timing marks on the crank pulley where off to. I didnt pay much attention to this as it began raining big time, and just before heading inside I was very interested in the huge timingchain slack measured on the crank my guess is it around 20 degrees. The distributor is very tight (as in no play in the gear) when moving it by hand, and my believe is there is supossed to be NO timing chain slack, correct????

Is there an easy way to check the harmonic balancer for slipping, or is it removal?

oldcutlass

A small amount of slack is normal, 20 degrees means its way past time to change it.

Jandk

Oops.. It was running so well !! The 20 degrees was measured by setting the wrench at 2 o'clock and by the time the distributor moved, the wrench was close to 3 o'clock...

This means, my problem Setting it on the marks, could mean the chain have jumped a tooth too?

Its only a 77.000 miles engine. What could be the reason for such a worn chain, this "early" ?

m371961

77,000 is about right for a original style chain and gears.

Jandk

Thats nice to hear....

Jandk

Can the chain gear be upgraded, and would it be recommended? Maybe combined with a new valvetrain ?


Does anybody know of FalconPerformance
http://stores.ebay.com/Falcon-Sales-...4.l1581&_pgn=2

Or would it be recommended to look elswhere?

Tedd Thompson

If mine I would check the harmonic balancer first . If you are getting rotation on the balancer and it changes each time you check it the rubber has probably become de laminated and is starting to fail. Could be a timing chain but after 50 years both would be subject to fail and should be replaced as a good maintenance procedure.... Tedd

D. Yaros

I second inspecting the harmonic balancer. Not likely a chain would repeatedly slip/change. It could stretch and but the new reading on the timing would not repeatedly change, IMHO.

Jandk

Ofcause while I am at it, I will check the balancer, but as I understand it the chain IS worn, so no matter what, I will have the parts removed.

olds 307 and 403

I did the same thing, put lower octane in and it seemed to ping from there out. I slowed the timing curve and added very cold plugs both helped but did not eliminate it. I finally used a good combustion chamber cleaner and removed the choke plate. I think the choke plate did help but I think the lower octane left deposits in the chamber. I honestly had almost no issue till I tried lower octane. Spray a good combustion chamber cleaner, spray it till it stalls. Open the linkage and spray more, let it sit a few hours or overnight.

MDchanic

Since your timing mark keeps moving, you almost definitely need a new harmonic balancer.

Since you have about 20° of crank play before the distributor moves, it seems like you also need to replace the timing set.

Two separate problems.

- Eric

Jandk

Eric: Yes I am aware of this. I will properly take it apart tomorrow or the upcoming weekend to inspect thar parts. But why **** the car have been driving so well for a long time (properly not perfect) and suddenly goes crazy is wierd.

Olds307and403: Some time ago I did do a cylinder clean, but I didnt leave it over night. I am sure this isnt the problem now... This is mechanical.

Tedd Thompson

If that motor is the high compression motor you will forever be plagued with ping if you use the lower test gas. Back in the day they sometimes would ping with the best gas we could find. and it would vary from station to station I'm sure our new gas is much inferior in octane than the old stuff... Tedd

Jandk

It is a high compression engine. I would never have thought you had problems with pinging back then.

MDchanic

That engine was designed for 100 octane on the scale you use in Europe.

Back in the 1960s, they were fine, so long as we used 100 to 102 octane.

- Eric

Jandk

Ah.. I see

cjsdad

While the timing chain will wear and stretch over time, the culprit may very well be the cam gear. The fiber teeth on the camshaft gear dry up and crack over time and can then fall off. This can cause immediate loosening of the timing chain and erratic ignition timing.

Since they very rarely get opened up for inspection before failure it is uncommon to see the fiber gear whole. I took a picture of mine when taking my wrecking yard engine apart for a rebuild because it is so unusual.

20160305_192310%201_zps4xid459p.jpg

Here is what they usually look like with the synthetic teeth completely worn or broken away.

MDchanic

Did the 394s have nylon teeth?

- Eric

cjsdad

OOOH! Ri don' know Raggie. I didn't remember that from the original post. My experience doesn't include that series of engines so they may not have.

MDchanic

I honestly don't know anything about the First Generation timing set, but in the 1961 Manual, it looks like solid steel.



- Eric

oldcutlass

Look theres a tool for that.

Jandk

This is very interesting. Very nice to see for real what actually CAN happen with these gears. Mine is a 77miles engine, that does not seems to ever have been openend, therefor no new gear/chain... I guess

didnt Oldsmobile have problems with these gear back then ??

Jandk

My chain and gear are now pulled off, and they are not in such a bad shape as the one in your picture cjsdad, but my chain is loose.

I tried checking my crank pulley, if the vulcanisation should have come loose. I tried tapping it with a brass dowel, and I cant not turn the outerring from the center.... Will it be good enough??

MDchanic

If your chain is loose, then the whole timing set (gears and chain) should be replaced.


No.

You need to accurately locate TDC on #1 cylinder.

With your heads attached, the best way to do this is with a TDC checker (you can buy one or make one by tapping a thread in the base of an old spark plug and screwing in a bolt).

You screw the screw into the cylinder until the piston crown touches it, and try to do this as close to TDC as possible, then mark the spot on your harmonic balancer.
Once you've set the screw, you turn the crankshaft all the way around until the piston crown touches the end of the screw again, then mark that spot.
Finally, you measure between the spots, and the point directly in the middle is TDC.
If the TDC mark on the balancer is not exactly where your mark is, the balancer ring has moved.

- Eric

Jandk

I got it... I just assumed I could double check it by tapping it, as if it has come loose, I would guess I could move the outer ring :-)

Thanks

MDchanic

The rubber can feel pretty tight but still shift slowly with crankshaft movements.

- Eric

Jandk

And it is old. Its properly best to have it rebuild.