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Timing a tooth or 2 off?


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Marco1974
Novice

Sep 9, 2018, 11:22 AM

Post #1 of 11 (255 views)
Timing a tooth or 2 off? Sign In

1996
GMC
C1500 Suburban
5.7L
35 Miles on new crate motor

Hello,
I recently replaced my engine with a new crate motor, after getting everything put back together the engine fired up and seemed to be running fine.. no codes or anything. I started the break in process of the new engine and after about 20 miles decided to hook up my cheepo ebay wifi OBD2 scanner and just make sure all was looking good.. Well I noticed that the timing said it was -22 degrees.. which kind of shocked me, I know the computer controls much of the timing but when i installed the distributor I had it at TDC with the rotor pointing right at cyl 1, so im not sure how it could be this far off.. i then decided to try manually adjusting the distributor which didnt help much (now its hovering around -20 degrees) and starting to throw error codes and I can tell it's slightly misfiring.. any ideas? could I be a tooth or 2 off and the computer actually be adjusting for that much of a difference? or could it be the OBD2 reader? it's a $20 ebay one that connects to the Torque app on my phone..

I appreciate any input, I'm an old shadetree gearhead that has swapped plenty of older engines, but not used to this newer tech (haha now i feel old when i say 1996 is "newer" tech)

-Marco


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 9, 2018, 12:08 PM

Post #2 of 11 (250 views)
Re: Timing a tooth or 2 off? Sign In

Did this come with the distributor or use the old one? The "R" code engine is not adjustable by turning it BTW it must be set in close and then set by your scanner then ECU takes over forever more. Don't turn those unless somehow it's not an "R" code thought all were says Vortec on it clear as a bell. Timing chain should be as you remember like any Chev. engine easy as they get but you can't see it. No reason to believe it's off by 1-2 teeth by 3 it wouldn't run well or at all if so,


T



(This post was edited by Tom Greenleaf on Sep 9, 2018, 12:13 PM)


Marco1974
Novice

Sep 9, 2018, 12:40 PM

Post #3 of 11 (241 views)
Re: Timing a tooth or 2 off? Sign In

Thanks Tom, I didn't think I was off because initially it ran nice and smooth.. This is a new distributor that I bought. So I think maybe I will pull the dist cap, set it back to as close as I can, since it seemed to be running just fine at that point and then take it in to a shop and let them dial it in.. my scanner doesnt have any adjustment options, it just shows what the computer is saying..

-Marco


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Sep 9, 2018, 1:01 PM

Post #4 of 11 (235 views)
Re: Timing a tooth or 2 off? Sign In

Have this engine right now and never touched it so just know you don't touch the distributor on them for anything but replacing it as you now said you did. Timing is set by computer you don't turn it the smarts can be exact vs how distributors you are thinking of adjust by RPM and even vacuum you set with those disconnected or as it said Underhood even tons older.


NO - just do lube those torx headed bitchy bolts will stick in no time for distributor cap.


BTW - you said "crate" engine and I only know of them do NOT all come the same way being long or short blocks with assorted stuff or not depending on what you found. Yes it probably was rebuilt not truly new but don't really know that the engine blocks either 5.7 or 7.4 (350 or 454) have been gone since model year 1999 I think?
Be glad it's running at all you do have to be close then set it by hand held device to be spot on then leave it and would seek that out for the check don't bother buying too much it's obsolete by now for most. Point is tell you that YOU are not going to set it from a cell phone thing so lucked out that it runs at all most don't for what you did!


Tom



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 9, 2018, 1:38 PM

Post #5 of 11 (230 views)
Re: Timing a tooth or 2 off? Sign In

You said it started setting codes. It wasn't a P1345 by chance was it?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Marco1974
Novice

Sep 9, 2018, 2:01 PM

Post #6 of 11 (228 views)
Re: Timing a tooth or 2 off? Sign In

It shouldn't have damaged anything by my having tried to manually turn the distributor correct? It wasn't much, the intake manifold gets in the way of turning it a lot.. and this was a crate engine that I purchased from JEGS (it's supposed to be a "new" long block but I wouldn't know how to tell if it was rebuilt.. not that I am too concerned about that as long as it runs fine)

-Marco


Marco1974
Novice

Sep 9, 2018, 2:09 PM

Post #7 of 11 (226 views)
Re: Timing a tooth or 2 off? Sign In


In Reply To
You said it started setting codes. It wasn't a P1345 by chance was it?



I don't recall what they were, but will check when I get home from work. It showed 3 of them..

- Marco


Hammer Time
Ultimate Carjunky / Moderator
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Sep 9, 2018, 2:18 PM

Post #8 of 11 (220 views)
Re: Timing a tooth or 2 off? Sign In

They changed systems in that year. If you have a P1345, then your timing is simply not adjustable. All moving the dist does is throw the primary and secondary ignition and the fuel injector all out of synch.

You would need a scan tool to read the cam offset and adjust it to 0.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Sep 9, 2018, 2:18 PM)


Marco1974
Novice

Sep 9, 2018, 8:41 PM

Post #9 of 11 (192 views)
Re: Timing a tooth or 2 off? Sign In


In Reply To
They changed systems in that year. If you have a P1345, then your timing is simply not adjustable. All moving the dist does is throw the primary and secondary ignition and the fuel injector all out of synch.

You would need a scan tool to read the cam offset and adjust it to 0.


I re-ran the scan and this time the only one that comes up was in fact the P1345 like you said.. so if I manually adjust the distributor back to were it was before I moved it, and clear the code would that be the best position to take it to the shop? or does that not matter and should I leave it there and let the shop do it? either way im taking it in because I don't have the right equipment to adjust it.

-Marco


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Sep 10, 2018, 5:37 AM

Post #10 of 11 (181 views)
Re: Timing a tooth or 2 off? Sign In

You are going to have to get it as close to 0 as possible if you expect to drive it. Just remember, it is not timing that you are changing so a timing light is worthless.
The timing is determined by the Crank sensor. All the distributor does is synchronize the primary, secondary and injector pulse to a single firing point.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Marco1974
Novice

Sep 10, 2018, 9:43 AM

Post #11 of 11 (168 views)
Re: Timing a tooth or 2 off? Sign In


In Reply To
You are going to have to get it as close to 0 as possible if you expect to drive it. Just remember, it is not timing that you are changing so a timing light is worthless.
The timing is determined by the Crank sensor. All the distributor does is synchronize the primary, secondary and injector pulse to a single firing point.


Thank you, I really appreciate the help!






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