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Marco1974
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Sep 9, 2018, 11:22 AM
Post #1 of 11
(2120 views)
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Timing a tooth or 2 off?
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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
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Sep 9, 2018, 12:08 PM
Post #2 of 11
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Re: Timing a tooth or 2 off?
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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)
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Marco1974
User
Sep 9, 2018, 12:40 PM
Post #3 of 11
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Re: Timing a tooth or 2 off?
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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
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Sep 9, 2018, 1:01 PM
Post #4 of 11
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Re: Timing a tooth or 2 off?
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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
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Hammer Time
Ultimate Carjunky
/ Moderator
Sep 9, 2018, 1:38 PM
Post #5 of 11
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Re: Timing a tooth or 2 off?
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You said it started setting codes. It wasn't a P1345 by chance was it?
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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.
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Marco1974
User
Sep 9, 2018, 2:01 PM
Post #6 of 11
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Re: Timing a tooth or 2 off?
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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
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Hammer Time
Ultimate Carjunky
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Sep 9, 2018, 2:18 PM
Post #8 of 11
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Re: Timing a tooth or 2 off?
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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)
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Hammer Time
Ultimate Carjunky
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Sep 10, 2018, 5:37 AM
Post #10 of 11
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Re: Timing a tooth or 2 off?
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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.
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