Timing 396/325 - Team Camaro Tech
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post #1 of 17 (permalink) Old Sep 24th, 05, 04:07 PM Thread Starter
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Smile Timing 396/325

Wondering if someone can tell me what can cause erratic timing. I have ruled out vaccuum leaks in that I have plugged all vaccuum ports and checked manifold and carb with ether. Still erratic. I tested fire on coil and it checks fine. Could distributor cause this? Could timing chain be off one to tooth?

EricE
68 Butternut Yellow
SS Coupe 396/325
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post #2 of 17 (permalink) Old Sep 25th, 05, 05:46 PM
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Re: Timing 396/325

Quote:
Originally Posted by stope4
Wondering if someone can tell me what can cause erratic timing. I have ruled out vaccuum leaks in that I have plugged all vaccuum ports and checked manifold and carb with ether. Still erratic. I tested fire on coil and it checks fine. Could distributor cause this? Could timing chain be off one to tooth?
What kind of distributor?

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post #3 of 17 (permalink) Old Sep 25th, 05, 09:41 PM
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Re: Timing 396/325

And what do you mean by "erratic"?...won't return to your initial setting after revs?
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post #4 of 17 (permalink) Old Sep 26th, 05, 11:23 AM
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Re: Timing 396/325

If you mean you see the timing jump around when you have a timing light on it make sure the pickup is ONLY touching the #1 plug wire and not any other wires. Even if its just barley touching another wire it could be getting a signal from both leads causing the erratic timing reading.


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post #5 of 17 (permalink) Old Sep 26th, 05, 04:53 PM Thread Starter
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Re: Timing 396/325

I have an original distributor where the points were replaced with the M&H Electric Fabricators Breakerless SE Single Wire Ignition. Have a standard replacement coil. here's the web site.

http://www.breakerless.com/

By errratic I mean the timing setting does not stay constant or even close to constant at idle.

The #1 timing light connection is not even close to another wire.

EricE
68 Butternut Yellow
SS Coupe 396/325
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post #6 of 17 (permalink) Old Sep 26th, 05, 10:36 PM
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Re: Timing 396/325

I'd bet your advance springs are too weak or your mechanical advance is sticking,..not closing all the way all the time. Try the next stiffer spring,..should fix her up.

Good luck!
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post #7 of 17 (permalink) Old Sep 26th, 05, 11:18 PM
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Re: Timing 396/325

Could also be carbon tracking inside the dist cap, just a chance
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post #8 of 17 (permalink) Old Sep 27th, 05, 04:04 PM Thread Starter
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Re: Timing 396/325

These may be dumb questions but here goes:

How do I know what springs I have and how do I tell which ones to get? Where do I get new springs?

When you say carbon tracking, what do I look for to determine if this is what it is?

EricE
68 Butternut Yellow
SS Coupe 396/325
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post #9 of 17 (permalink) Old Sep 27th, 05, 10:04 PM
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Re: Timing 396/325

The advance springs are under the rotor which is under the distributor cap. You may have a broken one (rare) or a previous owner may have put too light a spring thinking a quicker advance would save a full second in the quarter (not so rare).

Regardless, Mr. Gasket sells an advance kit with an assortment of springs,..part number #927 is used for our old points-style distributors. There's another kit for the HEI. About $7. Start with the medium springs,..see if the timing is more consistant. While the rotor is off, it wouldn't hurt to damp a cloth with a little WD-40 and clean the weights...to make sure they're moving freely.

Good luck!
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post #10 of 17 (permalink) Old Sep 29th, 05, 06:15 PM Thread Starter
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Re: Timing 396/325

Summitt Racing shows Mr. Gasket part number 927 for distributors after 1969. Part number 925A shows for distributors pre 1969. I do not know what the difference is between these. I thought 69 and 68 distributors were very very similar, if not the same. Any suggestions?

EricE
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post #11 of 17 (permalink) Old Sep 30th, 05, 12:37 PM
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Re: Timing 396/325

I was thinking that the # 927 part number would work on all pre-HEI distributors,..1973 and earlier.

You might call Mr. Gasket and see.

Good luck.
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post #12 of 17 (permalink) Old Oct 4th, 05, 07:31 PM Thread Starter
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Re: Timing 396/325

Checked the springs. They looked new but changed them anyway. The timing appears to have become stable. I can now set timing at 4, 6, 8 BTDC and the mark stays steady on what I set it at when shining the timing light on the balancer. When I up it to 12, 14 etc, I still see the unstaedy movements but it is not nearly as bad. I guess I can change to a third set of springs and see what happens. At least I feel that I am headed in the right direction. Thanks for all the help.

EricE
68 Butternut Yellow
SS Coupe 396/325
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post #13 of 17 (permalink) Old Nov 6th, 05, 08:14 PM Thread Starter
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Re: Timing 396/325

Update, timing has started jumping around again with a new twist. Now, when I rev from idle to 2500 rpms, timing advances to about 12:00 and then jumps back to about 6 - 8 degrees and stays there. Is this normal?

EricE
68 Butternut Yellow
SS Coupe 396/325
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post #14 of 17 (permalink) Old Nov 7th, 05, 08:14 PM
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Re: Timing 396/325

Double post
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post #15 of 17 (permalink) Old Nov 7th, 05, 08:15 PM
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Re: Timing 396/325

At a steady 2500 you should show 20-25 degrees of timing, which you won't be able to calculate unless you have a timing tape on your balancer.

Do this. Unplug the vacuum advance, and set your initial timing (at idle) at 8-10 degrees.

Reconnect the VA.

Readjust your idle speed.

Work the throttle with your right hand and watch the balancer with your timing light.

Make sure the timing mark is returning to the same place after each rev. If it doesn't, we need to take another look at what's going in the distributor.

Also, watch to make sure the line on the balancer moves way past the timing tab (on timing chain cover) on higher revs.

Let us know.
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