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Guest Message by DevFuse
 

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86 gl with high timing advance.

timing / vacuum advance

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8 replies to this topic

#1 jeffsimons

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Posted 23 July 2013 - 06:00 PM

I have recently received a 1986 GL Wagon that used to run great after normal tune up stuff. I haven't done it for about 2 years, it was my mothers car. The car currently runs and starts great up to about 3500 rpm the it acts weird. Checked the timing and it is at 6deg BTDC, just as the book says. When I rev the engine the timing goes completely off the chart, unreadable. When it gets high enough, somewhere in the 4k range the secondary starts to kick in. Seems to run normally unless driving, under load. Any suggestions would be appreciated.



#2 ferox

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Posted 23 July 2013 - 07:18 PM

I have recently received a 1986 GL Wagon that used to run great after normal tune up stuff. I haven't done it for about 2 years, it was my mothers car. The car currently runs and starts great up to about 3500 rpm the it acts weird. Checked the timing and it is at 6deg BTDC, just as the book says. When I rev the engine the timing goes completely off the chart, unreadable. When it gets high enough, somewhere in the 4k range the secondary starts to kick in. Seems to run normally unless driving, under load. Any suggestions would be appreciated.

 

What do you mean when you say it runs weird over 3500 rpm?  Your timing should advance quite a bit with rpm, so far that sounds normal. 



#3 MilesFox

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Posted 23 July 2013 - 07:30 PM

Timing should be set to 8 deg BTDC.

 

The vacuum advance should be disconnectoed to get a static reading. Otherwise, the vacuum advance will make the timing move all over the place 9normal operation)

 

According to your post, the timing should be set to 8 deg as 6 deg is lower than spec.



#4 djellum

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Posted 23 July 2013 - 10:27 PM

base timing should be 8 degrees, as stated, wtihout the vacuum hooked up (but make sure to plug the hose so you dont have a vacuum leak).  the total (max) timing will be very high, over 40 degrees, but it moves around depending on your throttle position.

 

if you hit the throttle and the timing quickly moves high, then I doubt theres any significant problems with the system.  nothing that would cause any major problems at higher rpms.  I would check the vacuum advance and readjust the 2 degrees that you are short and give it a check.  if it remains problematic repost with some better explanations of what weird is.  I would suspect on the surface that its more likely a fuel system issue.



#5 jeffsimons

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Posted 24 July 2013 - 12:09 PM

Is the Chilton manual off by 2deg. I have set it at 6deg at 700rmp as the book dictates but if you guys say I need 8 than I'll give it a couple more.


Edited by jeffsimons, 24 July 2013 - 12:10 PM.


#6 NorthWet

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Posted 24 July 2013 - 12:57 PM

MilesFox is seldom wrong (or at least seldom far from correct), and Chilton's tends to be next to worthless.  Chilton's crams a lot of different models into one manual, and it is easy for them or for you to grab the wrong info.



#7 MilesFox

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Posted 24 July 2013 - 01:22 PM

The vacuum schematic/emissions info sticker under the hood will state the timing. Provided you have the original engine and original hood.



#8 ferox

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Posted 24 July 2013 - 01:32 PM

I believe timing specs are usually given as 8 degrees BTDC plus or minus 2 degrees, so 6 degrees is within spec, but 8 degrees is the timing setting that the engine was designed for.



#9 scoobiedubie

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Posted 24 July 2013 - 10:36 PM

Just checked the manual.  For a manual transmission, it is 8 degrees BTDC at 700 rpm.  For an automatic, it is 8 degrees BTDC at 800 rpm.






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