Timing Chain Issue?

[npbsurfr]

Interesting issues...First off, for a few years now I?ve had a slight ping happening within my engine. Not much to worry about and every motor head I know have mentioned that it?s just an old engine.

My current issue is this.

Recently, within the past two days I?ve noticed the issue to be getting worse and worse and I fear absolute engine failure is eminent.

Idle smoothness varies a bit, but on acceleration I notice what appears to be a misfire. There?s no backfire so I?m pretty sure it isn?t an ignition issue. It just seems as if the engine dies off for a piston.

For the past three days it was barely even an issue until today. Idle isn?t bad, a little rough as always, but while on the freeway I can feel that single non-firing sensation and during acceleration as ell. The ignition system is fine, the timing is fine, the carburetor is fine, the exhaust is fine, the CTOs/Emmision systems are fine but I can?t figure out what this is.

At first I was freaking out because I had the slightest doubt of my transmission which is only 3 years old.

I don?t know if the issue is gradually getting worse or if my timing belt might have skipped/skipping. The engine was rebuilt at 100K and I?m currently on 220K.

Regardless I know I?m due for a rebuild, but money is an issue so I?m looking for a second car that will make payments on gas consumption alone.

Money is an issue, so let?s troubleshoot this issue.

Thanks guys!

1977 Jeep Cherokee Chief
AMC 360cui

[andy d]

check the cto which controls dizzy vacuum, might be as simple as a bad hose.

[GWChris]

If the timing chain skipped a whole tooth, I'd think you'd notice more than that, as the cam timing would be off too. If it's just streched some, then maybe. However, the chain would likely to have moved back, which would retard your timing.

Check the advance plate to make sure it is not binding & getting stuck advanced. Look at the EGR, you'll get lots of detonation if that's not working - and there's always the possability of the EGR passages being plugged. Also, how do the plug look? How about arcing in the cap or wires?

I just re-read your post - is it pinging more now, or missfire, or both?

[80Laredo]

It could be the timing chain or it could be either of the gears that operate the distributor wearing. (cant remember the name)

[npbsurfr]

I haven?t checked the entire vacuum system yet, but should be fine. I just replaced some parts, including the CTO, less than a month ago and every time I do some work I check the vacuum lines and vacuum. The plugs are fine since I just changed them on my last oil change. There isn?t more pining, it?s just always been there. I was curious if this could also be a problem in regards to this matter on the valve timing.

It?s not that it?s gradually getting worse, but more along the lines that last night while driving back home I realized how much worse it was. The engine wasn?t cold either since it was warm and required a short trip on a freeway. Also, when I tried started my car in the afternoon it turned about half way then froze. So I re-cranked it and it started right up.

This afternoon I?ll get dirty and check my entire vacuum system. The EGR was pulled apart about a year ago and cleaned. Maybe I?ll just replace it today

Now here?s a good question. All of my spark cables run along side of each other. The majority of the time they?re all clumped and wound together. Are there any separation pieces that would keep them apart? I?ve always questioned that, but oh well.

This afternoon I?m going to pick up the timing chain in case, EGR, and new wires, just in case.

Also, I?m looking to rebuild my engine within a few months. Are there any configurations, heads, cams, cranks, pistons, carbs that would increase mileage and performance?

7-10MPG

[80Laredo]

take your distibutor off and look at the gear on the end. ( going into the timing case.) make sure to mark where your distributor is before you remove it.

I just removed the timing case on a 78 360 not to long ago so if you decide to replace the timing chain any ?'s you have ask me.

[mechanical man]

Usually a timing chain skip results in very little power suddenly. The timing gears on my 87 were all metal (not the plastic ones GM uses) and not likely wear 'nuff to skip in 200K miles. I changed my timing chain only to find the problem was a $5 plastic carb float (GD Motorcraft 2150) that was saturated and flooding the motor.

[Krazy Dave]

To check a timing CHAIN all you have to do, is take your dist. cap off now put a wrench on the harmonic
balancer bolt turn the bolt one way watch the rotor, once it starts to move stop. NOW turn the bolt the other way you shouldn't have to move it more then 10-15 degrees before the Rotor starts to move. Any more then 25 degrees you have a bad chain
Timing chains are only good for 80k-100k mi
Timing chains streach and then the cam is not timed to the crank, causing rough running like it doesn't have enough advance. good luck.

[Krazy Dave]

P.S. use a 1972 and older timing set
Much better cam to crank timing

[Al Johnson]

Krazy Dave,

Did you miss a decimal point or something? Seems to me like 10-15 degrees of slop would be an INSANELY large amount.

npbsurfr,

Another possible cause for the poor performance is worn cam lobes. I had cyl#2 cam lobe just about gone on my 360 when I tore it down, and it had been running pretty poorly.

Good luck!
Al

[npbsurfr]

OK, here?s what I?ve come up with?

Unfortunately, I can?t get a timing chain for a few days, but here?s the diagnosis.

The vacuum gauge is reading 15.5-16.5 in mg, which could be a handful of issues; Late Ignition or Valve Timing; Low Compression; Stuck Throttle Valve; Leaking Carburetor; Leaking Manifold Gasket. The ignition timing is fine and was set correctly. For my own purposes I toyed around with it and it didn?t matter. I dropped the timing well BTDC, probably around 15-18? and ran much smoother too. All of which leads me to believe that it is the valve timing from the timing chain. Honestly, I still believe that the

Second of all, I just spent $90 at Kragen buying an ignition module that doesn?t even work let alone allow the car to start. I already expected such a thing to begin with. Once again, I still believe the timing chain jumped or stretched.

I had also checked the Vacuum Gauge Readings on this website which said 15 in HG was normal, but my Chilton?s manual is saying 20 in Hg flat is normal. So, if anyone knows the answer to this one it would be great.

Last of all, in which direction does the timing chain typically jump? It is coming to jump in the direction that created my BTDC issue with the ignition timing? If not, then it probably isn?t the timing chain.

As mentioned in my initial post, I have a slit ping going on. Honestly, I don?t believe this is the issue since I've had it for almost 40K miles.

Your help is awesome guys! Thanks!

[mechanical man]

My old 360, which I drove from 72-157K miles, pinged no matter what I did during those miles. I changed the timing chain, I put a Performer and Holley on it, I played with the timing, I got all the vacuum stuff up to snuff, replaced the EGR, etc. Nothing stopped the pinging. About two years ago I put a new motor in it and I can't get it to ping unless I push the timing way ahead-so far that it won't start when hot. I run stock timing now. I currently have the EGR disconnected due to some CTO problems and it still does not ping. I think the pinging problem in these motors is due to carbon build up and a rebuild it the only way to eliminate it.

[npbsurfr]

Does this appear to be a timing chain problem though?

[npbsurfr]

Alright, well I?m figuring 14.5? in difference between damper and rotation of the distributor. Who?s right, Krazy Dave or Al Johnson?

15? of does seem like a lot of slop when it comes to timing for me. I don?t know though. Does anyone know the correct answer?

Sorry about my last post... was on the phone while typing it out.

[npbsurfr]

OK, well I?m totally over this?

I pulled the distributor off to check the gears that run with the camshaft and now it won?t even start. I marked everything, and even figured the TDC of Cyl. #1 to verify ignition timing. Didn?t work.

As a matter of fact I almost blew my ears out when it back fired through the exhaust.

So, does anyone know of any good rebuilders in southern california that do a pretty good job for a very resonable price.

Thanks!