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-   -   85 impala timing (http://www.hotrodders.com/forum/85-impala-timing-224079.html)

85impala 09-16-2012 04:41 PM

85 impala timing
 
hey guys, i have a 85 impala with a 305, quadrajet, and its all computer controlled:smash: with esc:smash:

well i noticed my timing is off because i hear slight pops through the exhaust and it goes away when i jump pins A and B to stop the computer advance.

i bought an aftermarket timing pointer, found TDC and marked it on the new pointer. On the timing tape it shows 0* when the A and B terminals are jumped. and shows 20* when running normally at idle.

my questions are

1) is it normal for the computer to be advancing that much at idle?

2) where do i go from here?


Im very new at this, just bought the car this year so please bear with me:sweat:
Let me kno if you guys need more info

thanks,
clint

LATECH 09-16-2012 06:06 PM

20 is pretty normal .
Not to sure timing would be the issue here. Did the symptom occur after a timing adjustment? Did anyone adjust the timing?
Sounds like air getting into the exhaust stream. Maybe the EGR valve is sticking?
Could be also the carb is too rich. Also faulty AIR check valves can let air into the exhaust when not wanted and cause a pop or a burble.

85impala 09-16-2012 06:58 PM

Quote:

Originally Posted by LATECH (Post 1591263)
20 is pretty normal .
Not to sure timing would be the issue here. Did the symptom occur after a timing adjustment? Did anyone adjust the timing?
Sounds like air getting into the exhaust stream. Maybe the EGR valve is sticking?
Could be also the carb is too rich. Also faulty AIR check valves can let air into the exhaust when not wanted and cause a pop or a burble.

Well when I bought the car my buddy set the timing because it was running really rough. I didn't have a timing light so it was set by ear, and he put a chrome cover on of course.
I just noticed it now a few months after the timing was set, it sounds like a quiet pop or thump. No repetition or anything. I could only hear it when I'm by the exhaust and it kinda shakes the car. And I see a spike in the a/f when it happens, maby 16.0 max

I'm not sure what the AIR check valves are but I'll research it.

Theres a tube from my cat that comes up on the pass. side and it sucks, I'm not sure what that is.

We also replaced the huge stock air cleaner with a chrome one and removed the AIR tubes from the manifold

I have an a/f ratio gauge that's reading 14-15 so its not too rich

I'll check the egr valve, I didn't think of that.

Thanks for the reply :cool:

85impala 09-17-2012 11:46 AM

Here is a video that will probably describe the noise better than words,
It was taken on a cell phone so its crappy quality.

https://www.youtube.com/watch?v=KPeL...e_gdata_player">https://www.youtube.com/watch?v=KPeL...e_gdata_player" type="application/x-shockwave-flash" width="425" height="350">

I'll check the EGR valve and if I could find the AIR check valves I'll check that too later on today.

Thanks for the help
Any comments or ideas are greatly appreciated :)

85impala 09-17-2012 11:52 AM

Fail :smash:

Exhaust popping - YouTube "> Exhaust popping - YouTube " type="application/x-shockwave-flash" width="425" height="350">

LATECH 09-17-2012 04:18 PM

Sounds typical for a car with no exhaust system, however the tube on the passenger side that you said " sucks" needs to be plugged. It is allowing air to be pulsed into the exhaust stream...most likely causing the issue.

85impala 09-17-2012 05:00 PM

Quote:

Originally Posted by LATECH (Post 1591486)
Sounds typical for a car with no exhaust system, however the tube on the passenger side that you said " sucks" needs to be plugged. It is allowing air to be pulsed into the exhaust stream...most likely causing the issue.

Cool I'll do that, thanks for the help :thumbup:

85impala 09-17-2012 06:32 PM

That definitely worked, if I could hit the "thanks" button twice I would :D

LATECH 09-17-2012 06:43 PM

Excellent, glad to help:thumbup:

EagleMark 10-14-2012 07:05 AM

You can't set timing by ear.... these CCC and all GM EFI systems are usually set to 0 advance with Bypass wire disconnected, usually a tan wire with plug from the EST-ICM modle in distributor. ESC is module for knock system retard, Disconnect this wire and set timing to 0 with light. Then when plugged back in ECM will control timing and can be 10 to 20 degrees advanced. Will also set a DTC so disconnect battery to clear codes.

85impala 10-14-2012 11:25 AM

Quote:

Originally Posted by EagleMark (Post 1598941)
You can't set timing by ear.... these CCC and all GM EFI systems are usually set to 0 advance with Bypass wire disconnected, usually a tan wire with plug from the EST-ICM modle in distributor. ESC is module for knock system retard, Disconnect this wire and set timing to 0 with light. Then when plugged back in ECM will control timing and can be 10 to 20 degrees advanced. Will also set a DTC so disconnect battery to clear codes.

Cool, that clears things up a bit.
Thanks :)

Jim Rockford 11-18-2012 09:25 AM

yea you have to disconnect the by pass wire, One the b bodies its over near the passenger hood hinge area, and I hope the timing pointer was in the same place as the old cover, I know alot of those 80's SBC's had the pointer under the W/P at 12o'colck, using a aftermarket on with the side and not swapping the harmonic balancer with have the timing marks WAY OFF.

85impala 11-18-2012 12:16 PM

Quote:

Originally Posted by Jim Rockford (Post 1612646)
yea you have to disconnect the by pass wire, One the b bodies its over near the passenger hood hinge area, and I hope the timing pointer was in the same place as the old cover, I know alot of those 80's SBC's had the pointer under the W/P at 12o'colck, using a aftermarket on with the side and not swapping the harmonic balancer with have the timing marks WAY OFF.

Yea my factory timing pointer was around 12 o'clock right behind the water pump, but since my buddy got me a chrome timing cover without a pointer I had to buy a new 2 o'clock pointer which really screwed things up, so I found TDC again and made a new slit on the balancer inline with the new pointer:smash:
:D


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