Something that has alway's had me wondering! Specifically, slop resulting from normal usage?

The resulting effects who's cause is something that cannot really be called out by the standard troubleshooting methods. So these effects are many times just "lived with'!

1. What is the physical effect and resulting disfunction that occurs?
2. How prevalent is "Timing chain slop"?
3. What amount of slop, constitutes too much?

Inquiring minds want to know? (probably a few non-inquireing one's too!)

 

As far as preformance goes,the average person will not notice any difference until it actualy jumps timing.

I've seen them loose enough to rub a hole in the timing chain cover,and loose enough to lift the chain off the gears.

 

1. Cam timing is retarded even further...this is why checking the ignition timing is important...timing will be off

2. it happens...but the amount is up to you...if you are hard on the gas alot the chain will stretch much more...one instance is turning the corner and wingin the tire and then it grabs...that point at which the tire grabs stretches the chain...

3. 8 degrees on the timing tab....turn the engine counterclockwise to pull all slop out and on zero if you can...pull the distributor cap and as you turn the engine clockwise do so until the rotor button starts to move...count the degrees on the timing tab...if its more than 8 degrees replace the chain....

I ALWAYS go for a dual roller on replacement...soak them in oil and then install...installing a dry chain will stretch from the get go...splash from the front cam bearing is the only thing to lube the chain...you dont get much if any from the crank windage...

 

The spec I went by was to roll the engine so the chain was tight on one side - 3/4" of wiggle on the other side was the tolerance. At the time, I had 150,000 miles with 1-1/4" of slop.

Yep - the cam and timing will be late. Valves will open and close after their targets and the spark will be closer to TDC - which can be offset somewhat by advancing beyond spec. Hmmm, may have got that backwards in another related post a while back - doggone unreliable brain cells - maybe I needs to pull the codes? :-)~

 

I think "Doc" already covered it quite thoroughly but,

1.) Physical effect and resulting dysfunction? - From what I know, your power curve will move up in the rpm range, and could quite a bit. Also, achieving a "mystical" 16 degrees of ignition timing could prove to be troublesome... (Hmmm....)

2.) How prevalent? - well, it occurs in all timing chain driven engines. I would surmise it happens with belts as well but, I don't know for sure. It will happen, eventually.

3.) How much slop is too much? - Well, for people like you and I, I'd say "ANY" slop would be too much. Realistically, I'd say when performance suffers, it's probably due.


Funny, you should bring this topic up, I'm planning on swapping my timing chain set for a double roller with the abilitiy to advance the cam timing 4 degrees (thank you Doc Bowtie). It would seem my "power curve" is somewhere above 3,000 rpm and I want to pull it down to about 1,500-2,000 rpm so it's more useful. I believe I'll be able to acheive my 6 degrees of timing advance afterwards too! I'd call that a win/win situation!

Perhaps you DO have something to work on now "Y"!

 

4 degees advance will bring it roughly 500 rpm sooner...

the bad parts is as chains wear it does retard the cams timing but it also retards ignition timing...

retarding does move the curve up but greatly degrades low end power...

you dont notice it as it happens over time...

 

I suppose it depends on intended application, but based on application, where (RPM) should the timing curve be "all in"? And how do you best match to the power curve? In fact, who wants to define both & their "mystical synergistic" relationship! Here's where I start to get the ice cream "brain numb", w/o the ice cream.

 

I should check the timing chain on my 4.9.

 

Yep, after reading dr_bowtie, I fit the description for the need to check too! Not to mention what might have occurred during the 20 of it's 23 years, before I got it. I got a stack of paperwork for all repairs since the P/O bought it new. Nuttin about a timing change replacement.

 

he's being a smart ***...the 4.9L uses gear to gear....

on EFI dont worry about the timing...it varies according to your foot...