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timing


swoop
01-27-2006, 12:01 AM
I had posted this on another forum with no response. I have a 89 chevy sub. 5.7L that I have been trying to fix a hesitation problem with. I checked the timing and with the EST hooked up the computer had it at 0 degrees tdc. I then unhooked the EST and the timing went to 12 degrees advanced. So I set it to 0 degrees as per label on the radiator support. Hooked up the EST and the truck sounded and performed better. With no hesitation. Hooked the timing light back up and the computer has it about 9 degrees atdc. Im just wondering if anyone knows if that is where the computer is supposed to keep it. It ran great through out the power band, no hesitation and no sluggishness.

2000CAYukon
01-27-2006, 01:58 AM
0 degrees with EST disconnected. Should be around 20 with it connected but set it to 0 disconnected.

//2000CAYukon

romancatholicism
05-27-2006, 10:32 PM
Could someone please explain to me what the steps are in setting the timing for my 1990 Burb? Where exactly is this EST connection supposed to be disconnected and what does it look like?
I just fired my fresh rebuild today and the timing is at 0 with everything hooked up. Engine is a now a 357 sbc with TBI.

Elbert
05-28-2006, 06:28 AM
Could someone please explain to me what the steps are in setting the timing for my 1990 Burb? Where exactly is this EST connection supposed to be disconnected and what does it look like?
I just fired my fresh rebuild today and the timing is at 0 with everything hooked up. Engine is a now a 357 sbc with TBI.

ok I'll explain it....using my 92 K1500 pickup as reference. On the passenger side firewall under the hood you'll see a large black plastic cover (relay cover) it has three of those push-on plastic type nuts. Remove this cover. YOu should see a brown wire with white stripe...I think thats the right color, anyway it has a connector spliced in the middle of that section of the wire so you can disconnect it.

So you hook up your timing light and start engine, making sure you can read the timing mark and see the reference on the harmonic balancer as the engine runs. Good idea to buy a distributor wrench that fits your vehicle before you get started. While engine running disconnect brown wire and you'll notice that the engine changes in rpm.. Check timing at this point and adjust to 0 degrees as referenced on label under hood. THis is known as base timing. To set the timining you need access to the bolt at the bottom of the distributor that holds the distributor tight. Loosen the bolt and manually turn the distirbutor left or right to either advance or retard the timing. You just have to loosen the bolt a little so that you can move the distirbtor a little bit. Check timing to see where you are and once agjusted correctly tighen the bolt at the bottom of the distributor and re-connect wire and repace plastic cover. You'll also need to clear the check engine light that will be set by disconnecting the wire referenced above. You can do this by disconning the battery cable for a few minutes and then re-connecting.

ON these trucks you are concerned about the "base" timing. Because the computer controls the timing, you have to disconnect the wire in order to set the base timing.

I know my truck is real picky about either a little bit advanced or retarded base timing. It seems to run best at the suggested setting of 0 degrees.

Once again 0 degrees is base timing with the wire disconnected.

romancatholicism
05-28-2006, 07:33 AM
Thanks for the reply Elbert. I knew right off the bat that your post was not going to help me when you mentioned that your truck was a 1992...I dont have the relay box as you described. The rest was informative and applies to be sure, but I still need help locating the disconnect point for my 1990.....Chiltons manual is unhelpful as usual. Thanks to you and to any others that can help.

romancatholicism
05-28-2006, 08:31 AM
I think I found some insight as to where the EST Connector is after searching threds about timing. One guy mentioned that on his 1989 the connector was right near the wiper motor on the driver's side. Also, on later years, they moved it to behind the glovebox, near the heater core, or under the carpet at the feet of the passenger. I seem to remember diconnecting a single wire connector at the wiper motors' location while I was rewraping my wiring harness and painting my engine compartment. I will look there and post back.

romancatholicism
05-28-2006, 09:05 AM
Sure enough!!!!!!!!
The EST Connector is right next to the wiper motor on a 1990 R1500 Suburban 2WD w/5.7L
It is taped outside of the main split loom harness at the connector from the factory. It was evident that mine had never ever been disconnected in the 16 years of it's life. I'll set the timing to zero with the connector seperated later today. Thanks for all help received....(NOT you, Chiton's Manual!!!)

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