Thursday, November 18, 2010

How to install vortec timing chain. 5.7 1997 gmc 3500?

How do I know if my timing chain is installed correctly. The truck starts and drives but is slugish. I rebuilt the engine 2 years ago and has never been as good as new. I just took off the timing cover and here is what i see. With 1 piston at tdc and the dist rotor pointing to the 8 mark (1 connector) I see my timing gears as so.

Crank gear dot is at 12 oclock position.

cam gear is at the 12 0clock position. (If this is incorrect would it even start?)

Any Ides, before i change the timing chain.

This is a 1997 GMC 1 ton crew cab 5.7 vortec. at breakin the vortrc seemed to run good. shortly after it ran doggish It passed Immissions and inspection with flyin colors. it runs and drives and has recently been giving a p1345 code and will now not pass immisions untill i get the code to go away. Whe n I rebuilt the engine I reused the double chain and gear set cause it looked more durable, but I now think that was a mistake. I have the new one and its going in this weekend. any experience with this is appreciated.How to install vortec timing chain. 5.7 1997 gmc 3500?
I do agree they should be pointing at each other. But did you try turning the engine another revolution? but P1345 is for the CrankShaft position sensor. To fix a CSP after replacing it or setting timing on these trucks you need to connect it to a scanner. The timing is completely computer controlled.

Vortec Timing, 96 to 98. This is very common and after dealing with it a couple times on my own I felt I should add to this FAQ. Listed below is good for a v6 or v8, (just line your mark up to the 6, not the 8.) There are two processes to follow, I will list the more favorable A and alternate B:


First if you are doing a smaller job like intake gaskets etc, you want to mark the distributor. Mark the distributor housing to the intake with a grease pencil. Also mark where the rotor is pointing to on the base of the housing. I suggest doing this at TDC 1 compression stroke so that if you accidentally bump the motor over you can put it back. on tear down to find TDC turn the engine over manually until you line up the line on the balancer to the timing mark on the timing cover. Check the distributor and it should be pointing to a 8 in the housing of the distributor. you will note a 6 and an 8. The 6 is where it would have pointed if this was a 6 cylinder. If pointing to that little 8 then you are at TDC 1 compression, if it is pointing in the opposite direction you are at the top of the exhaust/intake stroke 1, not compression and you need to turn the crank a full 360 additional degrees.

on reassembly just make sure you are TDC compression and slide the distributor back in. If it doesn't sit flat on the intake try wiggling the rotor back and forth a bit to get the distributor gear to seat in the oil shaft. If this doesn't work you may need a long flat head screw driver to turn the shaft and properly align it.


If that doesn't work, or you forgot to make your mark or you did a full rebuild with new timing gears and need to get it set this is what you do. Find TDC 1 compression stroke. How do you find it? I found if you are alone the best is with a compression tester. you can turn it until you see it build pressure. I recommend you do this with all the spark plugs out, makes it a lot easier to turn over. If you have 3 hands or more available, you could have some turn the motor over while another puts a finger on the 1 spark plug hole and feel for pressure, once you feel pressure line the timing marks up. Being at TDC you can now move on. Get your distributor. Look on the lower part of the housing and you should see a white vertical line painted on it. Turn the distributor gear until the drilled hole lines up with the white line. look at the rotor and it should now point about at that 8. Stab the Distributor in with the wire harness connector facing towards the fire wall(more towards driver side). Once seated see if you can line of the rotor to the 8. If you can and can lock it down and put the cap on then you are good, if not you may need to re stab on a new tooth but the end result is you want the rotor pointing the the 8 on the housing. (now I am not talking about 8 cylinder, but in the distributor there is a 6 and 8, tiny but it is there.)

That should fire it up, if not then you messed something up and start over. You may need to pull your spark plugs and dry them (air compressor helps here) as I struggled with fouled plugs leading me to think I was wrong on the timing but wasn't.

Lastly once done with A or B, you should get a scan tool that will display the cam retard and you need to turn the distributor to set this to zero.How to install vortec timing chain. 5.7 1997 gmc 3500?
The dots should point at each other crank 12 o'clock and cam 6 o'clock, no wonder it runs bad. You don't need to change the chain, just point the dots together. You really need to get yourself a Haines or Chiltons manual so you will not make another silly mistake.How to install vortec timing chain. 5.7 1997 gmc 3500?
I believe the cam gear dot should be at 6 o'clock and the crank at 12 o'clock.

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