Timing Issues - Team Camaro Tech
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post #1 of 31 (permalink) Old Apr 8th, 10, 12:55 PM Thread Starter
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Timing Issues

My 81 Camaro will only ping while driving, it won't ping in park and when i turn the car off it runs on i have to put it into drive and shut it off without it running on, i think its a timing issue but i have never timed a car before can someone give me step by step in how to time it? i have a shop book and its says Timing (BTDC) 6? what does this mean?

and also the RPM are off like in park it will idle at 1400 then when you put it into drive it drops down to 900 how can i fix this

Thanks
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post #2 of 31 (permalink) Old Apr 8th, 10, 02:40 PM
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Re: Timing Issues

Pinging while driving sounds like you have too much timing causing detonation. It doesn't do it in park because there is no load. Your rpm drop from 1400 to 900 is too much which leads me to believe there may also be a carb issue.
Timing is set using a timing light and turning the distributor to advance or retard the timing. Your initial timing-Before Top Dead Center can vary depending on how much or how little cam you have installed. 10* BTDC should be a good starting point but you should try not to exceed a total of about 36* in total,( initial plus mechanical with the vacuum advance disconnected). There is a ton of info if you do a search. Timing is one of the last tuning aids to really dail in a motor. You can play with different vacuum cans and either ported or full manifold vacuum advance to see what your motor prefers.

Good luck.

John

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post #3 of 31 (permalink) Old Apr 8th, 10, 06:27 PM Thread Starter
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Re: Timing Issues

Also forgot to add the engine is not stock its been rebuild. i don't know what kind of pistons are in it but it does have a higher lift cam, hee is a video of the car runing http://www.metacafe.com/watch/276137...maro_z28_hypo/
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post #4 of 31 (permalink) Old Apr 8th, 10, 07:01 PM
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Re: Timing Issues

make sure your runnin premium!

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post #5 of 31 (permalink) Old Apr 8th, 10, 09:12 PM Thread Starter
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Re: Timing Issues

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Originally Posted by trackman View Post
make sure your runnin premium!
the previous owner said i can run it on regular 87 Octane
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post #6 of 31 (permalink) Old Apr 8th, 10, 09:39 PM
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Re: Timing Issues

When you shut off the key, there is no spark & therefore no timing.

You have run-on due to excessive throttle opening at idle (combined with poor fuel or combustion deposits in the chamber), which does not effectively "choke" off the car when you shut the key off.

Try reduce idle speed with idle screw. This should help the car stop running.
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post #7 of 31 (permalink) Old Apr 9th, 10, 10:18 AM Thread Starter
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Re: Timing Issues

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Originally Posted by Lonnie P View Post
When you shut off the key, there is no spark & therefore no timing.

You have run-on due to excessive throttle opening at idle (combined with poor fuel or combustion deposits in the chamber), which does not effectively "choke" off the car when you shut the key off.

Try reduce idle speed with idle screw. This should help the car stop running.
I've tried to reduce the idle speed but when you lower it to about 1000 RPM and put into reverse it goes to about 500 RPM and staals, the only way you can get it not to staal in reverse is by putting the idle at 1400 RPM in park
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post #8 of 31 (permalink) Old Apr 9th, 10, 02:09 PM
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Re: Timing Issues

If I were you I'd start looking for vacuum leaks.

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post #9 of 31 (permalink) Old Apr 9th, 10, 04:46 PM
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Re: Timing Issues

ya x2 on the vaccume leak. a quick check is to fire the car up let it warm up then put your hand over the choke buterfly and try and seal it off with your hand, if your engine starts to stall out or running realy rough I would start looking at the carb itself. If your engine does not stall out or acually speeds up a bit you have a vaccume leak some wear and the engine is sucking air from wear ever its leaking .
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post #10 of 31 (permalink) Old Apr 9th, 10, 04:52 PM
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Re: Timing Issues

If you have a large cam, you may have idle problems in gear with a tight stock torque converter.

In that case, get the converter combination correct as your idle fix is causing you other problems.

What are your cam specs?
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post #11 of 31 (permalink) Old Apr 9th, 10, 08:11 PM Thread Starter
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Re: Timing Issues

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Originally Posted by Lonnie P View Post
If you have a large cam, you may have idle problems in gear with a tight stock torque converter.

In that case, get the converter combination correct as your idle fix is causing you other problems.

What are your cam specs?
i was told by the previous owner its has a 3000 RPM stall converter, is there a way to tell if this is true? i have no cam specs
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post #12 of 31 (permalink) Old Apr 9th, 10, 09:04 PM
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Re: Timing Issues

Yes, put it in gear, hold the brakes & hit the throttle. See how high it revs before the rear tires start to spin. This will give you a close idea.
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post #13 of 31 (permalink) Old Apr 11th, 10, 05:58 PM Thread Starter
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Re: Timing Issues

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Originally Posted by Lonnie P View Post
Yes, put it in gear, hold the brakes & hit the throttle. See how high it revs before the rear tires start to spin. This will give you a close idea.
Its a 3000 RPM stall converter, I was messing with the timing all day and I still couldn’t get it right, I would retarded it little by little and it was getting worse it starter to ping in park but wouldn't run on. When I advanced little by little it was running way better and wouldn’t ping but as soon as it was under load it pinged and it was running on when you shut her down, what do you think the problem is?
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post #14 of 31 (permalink) Old Apr 11th, 10, 06:18 PM
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Re: Timing Issues

Quote:
Originally Posted by Lonnie P View Post
When you shut off the key, there is no spark & therefore no timing.

You have run-on due to excessive throttle opening at idle (combined with poor fuel or combustion deposits in the chamber), which does not effectively "choke" off the car when you shut the key off.

Try reduce idle speed with idle screw. This should help the car stop running.
I agree.

Also, do you have your vacuum advance hooked to manifold vacuum?
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post #15 of 31 (permalink) Old Apr 11th, 10, 06:56 PM Thread Starter
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Re: Timing Issues

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Originally Posted by 69ZL1 View Post
I agree.

Also, do you have your vacuum advance hooked to manifold vacuum?
no i believe its hooked up to the carb

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