Home » Public Forums » GMCnet » [GMCnet] setting timing
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| Re: [GMCnet] setting timing [message #164495 is a reply to message #164491] |
Wed, 28 March 2012 19:48   |
rssbob
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
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David, Are you using a timing light?
On Mar 28, 2012, at 3:29 PM, David wrote:
> Ok, so i was wrong, once i took a picture (and zoomed in) of the
> timing marks they are the same, so it seems that i am to set my timing
> at 8* btdc.. i can get 6 or 12. not sure what i am doing ... wrong
> that is.. but i set it to 6. turn it off. moved the dist. 1/4 inch.
> even measured. and it goes to 12, any clues as to the steps i am
> missing? sounds great just a little fast. I have not taken it for a
> spin with the new setting.
>
> any input would be appreciated.
> thanks in advance.
> --
> David Paliotta
> 75 Glenbrook
> Tulsa, OK
> http://75glenbrook.googlepages.com/
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Bob Sobrito
78 Palm Beach
La Mesa, Ca
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| Re: [GMCnet] setting timing [message #164524 is a reply to message #164479] |
Wed, 28 March 2012 22:23 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
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Mine is a '77 and not sure if the years matter, but it is a little weird in that the spec calls for setting timing at 1100 rpm. Most vehicles are checked closer to "normal" idle speed. Also, the vacuum line going to the distributor should be removed and plugged.
I was hoping some of the people with fuel injection would post for you, as if you have the distributor controlled by the engine control computer, that may affect what the base timing setting is. I still have the carb, and my sense is most of the fuel injection kits don't include spark control, unless you have added that yourself.
With lots of people in Shawnee, it may take a while to get some responses.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: [GMCnet] setting timing [message #164532 is a reply to message #164479] |
Wed, 28 March 2012 23:31 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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IF you have a standard HEI or points distributor then the setting of the timing is not different for an injection system than when you have a carb on it.
If you have a computer controller distributor then it is a whole different ball game.
If you have the OEM distributor (not computer controlled) just turn the idle down to 700 or 800 RPM, remove and block vacuum line to the distributor and have at it. I always adjust the timing with the engine running. Watch the light, rotate the distributor and tighten the lock bolt when you have the distributor where you want it. Then check the timing a second time to make sure it has not moved while you were tightening the bolt. You will find as you advance the timing that the idle speed will go up. Set it back as necessary and definitely set it again when you have finished setting the timing.
The engine does not have to be hot to adjust the timing. It just needs to be warm enough so the automatic choke does not increase the idle speed. Since you are injection you probably do not have a choke so that should not be a problem.
If you have a computer controlled distributor then the process changes. I have never done a computer controlled distributor in a GMC but on other GM vehicles there is a jumper that you install to prevent the computer from advancing the timing while you are adjusting it. When you are finished you must remember to remove the jumper.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] setting timing [message #164536 is a reply to message #164532] |
Wed, 28 March 2012 23:43 |
Dave Motorhome
Messages: 175
Registered: July 2007
Karma: 2
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Mine is controlled by the computer, I contacted turbo city to verify
the procedure, he said to unplug the timing wire (brown/tan). so that
was done, just seems that when i get it on 8* I kill the engine to
lock down the dist. I am trying to be very careful not to nudge it at
all. but when i start her up, she runs great just goes to 12 * (seems
fast rpm). so then i adjust it again retard to 8*..shut down the
engine.. lock down.. restart, then it goes back to 4 or 6*.. can not
seem to hit 8*, i will try again in the AM, i was getting frustrated
tonight, just thought i would send out an inquiry to see if i missed
anything, tonight i thought that i might need to adjust the idle on
the throttle body..
thanks again!
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
> If you have a computer controlled distributor then the process changes. I have never done a computer controlled distributor in a GMC but on other GM vehicles there is a jumper that you install to prevent the computer from advancing the timing while you are adjusting it. When you are finished you must remember to remove the jumper.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
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| Re: [GMCnet] setting timing [message #164543 is a reply to message #164536] |
Thu, 29 March 2012 01:38 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| Dave Motorhome wrote on Wed, 28 March 2012 21:43 |
Mine is controlled by the computer, I contacted turbo city to verify
the procedure, he said to unplug the timing wire (brown/tan). so that
was done, just seems that when i get it on 8* I kill the engine to
lock down the dist. I am trying to be very careful not to nudge it at
all. but when i start her up, she runs great just goes to 12 * (seems
fast rpm). so then i adjust it again retard to 8*..shut down the
engine.. lock down.. restart, then it goes back to 4 or 6*.. can not
seem to hit 8*, i will try again in the AM, i was getting frustrated
tonight, just thought i would send out an inquiry to see if i missed
anything, tonight i thought that i might need to adjust the idle on
the throttle body..
thanks again!
David Paliotta
75 Glenbrook
Tulsa, OK
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it sounds like you are doing it correctly. When the brown/tan wire is disconnected, the module is on it's own. Most modules have an advance built in sort of like the weights on a mechanical. This way, if you loose computer control you limp home a little better. So it is my guess that the faster idle is bumping the timing.
I don't have TurboCity, but if you had it at 8 before you shut it down the last effort, I would think it is ok. Once the brown wire is back on, the computer should then get you back to a normal idle.you can then check the timing. You will see that now it is so advanced that you see no mark... Probably around 20 degrees at idle.
If you hear no pinging, and it does not kick back when starting, I think you are good.
The computer is adjusting the idle speed. Fiddling with the idle screw is not going to change anything, and will put the TBY out of adjustment. It could be that it does need a tweak, but there is a set of steps to get it right.
There is another forum for EFI and some TurboCity folks there. We can also help you get the tbi adjusted. Write to me at gbeckman at pggp dot com and we can get you hooked up to the forum. I am not at my computer now.
I say drive it down. Look ip Randy Van Winkle and Bob Drewes. They can help. Take the timing light.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] setting timing [message #164544 is a reply to message #164536] |
Thu, 29 March 2012 01:43 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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On a computer controlled distributor the static timing is not that big of a deal. It is just a starting point for the computer. The computer takes over the actual timing and advances /retards the timing based on several inputs. The TPS, the knock sensor, and RPM are the three major input sources to the computer for adjusting timing on the fly. I do not know the actual programing in your computer so I am talking in generic terms.
I would just get it close and be done with it.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] setting timing [message #164562 is a reply to message #164479] |
Thu, 29 March 2012 10:04 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| Dave Motorhome wrote on Wed, 28 March 2012 13:14 |
i
even though mine does not seem to denote 0 4 8 ..... are the marks
universal? i should go over to the third ridge?
again sorry for my probable..very mundane question?
mine again are different, I will try to post a pic, but it is veryt
tight in there,
--
David Paliotta
75 Glenbrook
Tulsa, OK
http://75glenbrook.googlepages.com/
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I had one more thought. We have had some bad modules... Out of the box. Take a spare on your trip to GMCMI
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
[Updated on: Thu, 29 March 2012 10:05] Report message to a moderator |
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