To all TBI owners

[96k1500]

This is what I was thinking about doing.. don't want to put anything to far out of whack though.

My trucks sitting around 150 000 miles now, wondering if it'd be worth getting timing chain done & a new dizzy. Both have never been replaced

Prob wouldnt hurt to get them replaced

 

[88GMCtruck]

I did my timing chain and a full ignition tune up around 140k. You'd be surprised how much stretch a stock single roller timing chain gets in that amount of miles.

 

[94Sierra4x4]

Prob wouldnt hurt to get them replaced

Could hurt the wallet a bit
I haven't heard of anybody else replacing the timing chain, so no idea how long they generally last. Some of you guys have a lot more miles on these trucks than I do.

I did my timing chain and a full ignition tune up around 140k. You'd be surprised how much stretch a stock single roller timing chain gets in that amount of miles.

Some info to go on there, I'll have to make an appointment with a shop for this one, mind you. Timing & Brakes, not my business, lol.

 

[88GMCtruck]

Generally people leave them in till the motor dies. I noticed my timing fluctuating a tad and ended up replacing it. They aren't expensive.

 

[94Sierra4x4]

Generally people leave them in till the motor dies. I noticed my timing fluctuating a tad and ended up replacing it. They aren't expensive.

Okay, so generally they last a good while, still going to be worth looking into. How did you notice your timing was fluctuating?

 

[88GMCtruck]

Yeah it would be hard to break a timing chain in a stock motor.

My truck was knocking and throwing the SES light, i threw the timing light on it and it seemed to dance around a little more than i liked. Put a new chain in it and problem solved.

 

[94Sierra4x4]

Yeah it would be hard to break a timing chain in a stock motor.

My truck was knocking and throwing the SES light, i threw the timing light on it and it seemed to dance around a little more than i liked. Put a new chain in it and problem solved.

Hmm so if it was far enough out of time it would set off the SES light, well i'm not getting any trouble light, however haven't seen on in a while. SES light will come on with key ON engine OFF, correct?

 

[88GMCtruck]

Yes, that is correct.

 

[VorTecxas]

Just for s and gigs..
Is there anything you can do to check the timing, or advance/retard it to 0* without a timing light?
Like mark the dizzy, loosen it and turn it a c-hair, drive it to see if symptoms cleared up/changed?

Is it even worth screwing with, without a timing light?

Yes. Remove your dist cap and turn your crank with a breaker bar using the hold down bolt in the center. I believe it is a 16mm, don't quote me though. Turn it until the timing mark lines up with the big indention on the tab and your rotor is pointing close to where your #1 wire was. You are now at TDC on the ignition stroke. If your rotor points at where your #6 wire was, that is 180 degrees out, make one more full rotation with the crank and you should be set. Now here's the iffy part, you now need to make sure that your rotor is pointing exactly where the #1 wire goes on the cap. Simple way is a use a paint pen or something similar, put your cap on (or do this before taking it off) and mark on the distributor housing where your #1 wire is at. Now remove the cap and line it up with the rotor tip as best you can. Tighten down the dist, reconnect everything, and fire her up. There's not really a way to check while running without a light, unless you have access to a scanner that will read OBD1

You can also do this to advance or retard it, each mark (we'll call them "peaks" and "valleys") is 2 degrees. So the deep valley is 0, the peak next to it is 2, the valley next to it is 4, so on and so forth. Use the same process, just put the balancer mark where you'd like your timing to be. This is a good way to test how your truck responds to different octane fuels, higher or lower heat range plugs, etc.

 

[VorTecxas]

Another thing I will add to this, if your motor is higher mileage it's worth replacing your timing chain. They do stretch over time and it can make the timing walk around.

Giggity. Good catch. Don't know why I didn't mention that, I've replaced more than I'd care to.