Wierd Timing Problem---shade tree at fault?
09-29-2001, 02:14 PM
#1
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Car: 1989 IROC-1
Engine: L98
Transmission: 700r4
Wierd Timing Problem---shade tree at fault?
I had a new cam put in my 84 Z with an L69. Comp cams 12-238-8.
I installed the same cam # about 6 months ago. It didn't work properly. The lobes didn't appear to have been worn off during break in...but I neglected to degree the cam during installation!!!
I took the car to the local shade tree mechanic (I've had a back injury and can't do anythign that extensive). He put a new cam in and the car runs. However, he rigged up the cooling fan, rewired it so it is always on, did something to make the gauge lights not work, has the tach all screwed up and some other issues.
Here is the wierd thing though...maybe someone has an answer.
I suspected that the timing was off, so I check it. The ding-dong told me it was about 10 to 12 degrees. I check it and the timing is at like 20* initial!!! I re-adjusted it to be at about 10*. Had to turn it quite a ways.
It ran pretty well for the next 10 days or so. Has much better power at part throttle than before the cam swap, but not what I expect at WOT, even a little hesitation (timing again I believe).
I took it for a long ride yesterday. It got a little warm at stop lights. The warmer it got, up to about 230, the rougher the idle got. When I would take off and cool the car down a bit, the idle would settle down and smooth out. I knew I had some older ignition components in there....
I knew the cap was worn so I swaped it out with a new cap and coil I had. I checked the wires, and the shade tree mechanic had the 6 and 8 plug wires crossed.
I put on the new cap and coil, changed nothing else.....car WON'T start...back fires through carb. I wiggled the timing forever, until I got it to start. Re-timed it, and now it is at 10* again, but nowhere close to the same position it was in before.
All I did was swap out the cap, coil and switch the 6 and 8 plug wires to be where they should.....
Now it starts better than before, and still has good throttle response......Before I had a tiny, barely noticable, little stutter when I shut it off also...not anymore.
I checked to make sure that it was NOT missing by putting the timing gun on each wire, and they all fire. Idle is smooth, starts easily, shuts off quitely....
So, what can cause such a problem?
I installed the same cam # about 6 months ago. It didn't work properly. The lobes didn't appear to have been worn off during break in...but I neglected to degree the cam during installation!!!
I took the car to the local shade tree mechanic (I've had a back injury and can't do anythign that extensive). He put a new cam in and the car runs. However, he rigged up the cooling fan, rewired it so it is always on, did something to make the gauge lights not work, has the tach all screwed up and some other issues.
Here is the wierd thing though...maybe someone has an answer.
I suspected that the timing was off, so I check it. The ding-dong told me it was about 10 to 12 degrees. I check it and the timing is at like 20* initial!!! I re-adjusted it to be at about 10*. Had to turn it quite a ways.
It ran pretty well for the next 10 days or so. Has much better power at part throttle than before the cam swap, but not what I expect at WOT, even a little hesitation (timing again I believe).
I took it for a long ride yesterday. It got a little warm at stop lights. The warmer it got, up to about 230, the rougher the idle got. When I would take off and cool the car down a bit, the idle would settle down and smooth out. I knew I had some older ignition components in there....
I knew the cap was worn so I swaped it out with a new cap and coil I had. I checked the wires, and the shade tree mechanic had the 6 and 8 plug wires crossed.
I put on the new cap and coil, changed nothing else.....car WON'T start...back fires through carb. I wiggled the timing forever, until I got it to start. Re-timed it, and now it is at 10* again, but nowhere close to the same position it was in before.
All I did was swap out the cap, coil and switch the 6 and 8 plug wires to be where they should.....
Now it starts better than before, and still has good throttle response......Before I had a tiny, barely noticable, little stutter when I shut it off also...not anymore.
I checked to make sure that it was NOT missing by putting the timing gun on each wire, and they all fire. Idle is smooth, starts easily, shuts off quitely....
So, what can cause such a problem?
09-29-2001, 03:06 PM
#2
Gruve,
Of course, you disconnected the vacuum advance and EST timing connector before setting the base timing, right?
Having #6 & #8 reversed should have made for a terrible idle, running on six cylinders and having the dead cylinders unevenly spaced in the firing order.
Another thing you should do is set the TPS on the carb, then the mixture control solenoid. Search the archives by "mixture control" and you should find a lot of posts with directions.
------------------
Later,
Vader
------------------
Justice and Freedom will Prevail
Of course, you disconnected the vacuum advance and EST timing connector before setting the base timing, right?
Having #6 & #8 reversed should have made for a terrible idle, running on six cylinders and having the dead cylinders unevenly spaced in the firing order.
Another thing you should do is set the TPS on the carb, then the mixture control solenoid. Search the archives by "mixture control" and you should find a lot of posts with directions.
------------------
Later,
Vader
------------------
Justice and Freedom will Prevail
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