Just did tuneup, need timing adjustment help

[dynmicracr]

I just got through replacing the following items:

cap
rotor
plugs
wires
o2 sensor
map sensor
IAC
fuel filter - Still have it, but have not done it yet.

I have a question regarding setting the timing. With the brown wire connected it was off the charts as far as timing goes. With it disconnected it was at about 4 deg BTDC. I adjusted the timing and set it to 0. Tightened the distributor back up, reconnected the wire and its back at -4. Also, with the wire connected, my idle is at about 1K where it supposed to be, with it disconnected it goes down to 800 or so. So my questions are can you check the timing with the wire disconnected, and why would the timing go back if I had it in bypass mode when I set it? Why is the car so dramatically different in bypass mode rather than not as far as timing and RPM are concerned?

Thanks,

Alex

 

[Wes]

Re: Just did tuneup, need timing adjustment help

If you have the original harmonic dampener there's a good chance the outer ring with the timing mark is loose, this is common and I would check for TDC by removing the #1 spark plug, putting a screwdriver or some sort of rod in the cylinder and turning the crank with a 5/8 socket and breaker bar. You can get a fairly accurate idea of where TDC is. If it's significantly different than the mark on the dampener you will need a new one.

At idle the computer puts in a lot of timing advance.

 

[supersports10]

Re: Just did tuneup, need timing adjustment help

THAT SOUND NORMAL. the computer is advancing the timing 4 degrees after you set it at 0 with connector off.

i just checked my jimmy in the same method and it was at 0 with connector disconnected, when connected it went to 4 deg advanced.

you said that with it disconnected it was at 4 deg advanced, and connected it was off the chart, this means that someone advanced it 4 deg, and you corrected it. it should be correct now.

 

[SeattleSy#1255]

Re: Just did tuneup, need timing adjustment help

i agree...set your timing by removing plug 1 wire, stick finger in hole and turn motor over manually on the alt. using a 1 incher if i remember correctly till you feel compression....you'll have to remove top fan shroud.... You'll feel air on the exhaust stroke, but should feel more on compression and you should be able to tell with your finger. I believe this to be easier when motor is cold, or the warm air is hard to detect on your finger IMO (because your fingers are warm). make sure rotor is installed between #1 and #6 tower on dissy. disconnect tan wire fire it up and check it...it should be close with perhaps a little adjustment needed. If you are way off, try to reinstall rotor 180 degrees the other way.

things to remember....there are actually 2 timing marks on the HB you want to use the furthest to the left if you are looking down at it from the front of the truck.

paint the markder white, it helps to see it later.

all timing should be done with tan wire unplugged.

 

[dynmicracr]

Re: Just did tuneup, need timing adjustment help

Hey everyone.... thanks for all the input! i adjusted the timing again last night. I have most of the detonating stopped. I think it was at about 4 BTDC. I was able to adjust it but it appears the distrubutor is moving the more I tighten it down. So I have it down to 2 BTDC. I think I need to do it again and make it 0. I might just start a little (-) so that when it slips it will be at 0. Since most of the pinging has stopped about 95%, that tells me my marks are still lining up (for now) . Now it just pings because I have an overboost condition. That is my next object to tackle. 20lbs is BAD!

http://www.syty.net/forums/showthread.php?t=25525

Thank you to everyone for the great help. I really appreciate all the feedback.

Alex