setting timing ?? - Team Camaro Tech
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post #1 of 11 (permalink) Old May 21st, 01, 12:49 PM Thread Starter
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I am tring to sett the over all timing on my 327 I was told that the motor should be running at 2800-3000 rpm.
when I do this and dail the light back to zero I come up with 58 degrees adv. ?
will a motor run that far adv. or Iam doing something wrong ?
the vacum IS hooked up?
the timing tag is off a 69 327 large jernal and this is a 67 small jernal is there a difference?

this motor is built up some has a mystery cam

thanks!!!!!!!!!

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post #2 of 11 (permalink) Old May 21st, 01, 12:54 PM
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You need to disconnect the vacuum and plug the source. You will get a much different result...

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post #3 of 11 (permalink) Old May 21st, 01, 01:51 PM
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Djd - I'm certain you should see around 36* even with the vacuum advance connected. With it disconnected you should see somewhere around 25*.

Yes! There is a difference! Pre-69 small blocks use a different pointer and vibration dampener than the 69 and later small blocks. The timing marks are several degrees off from each other - this would account for the weird timing reading you're getting. You need the pointer off a 68 or earlier small block to match your 67 vibration dampener. You can also remark your existing dampener, but that's tough to do accurately with the heads on.

Good luck.
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post #4 of 11 (permalink) Old May 21st, 01, 05:41 PM
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The only way the vacuum advance will go away is at WOT!! You cannot check the total timing with the vacuum advance connected. It could be putting as much as 15-20degrees of advance at part throttle!!

With vacuum disconnected a small block should like anywhere between 32-38 deg's of total advance... 4speeds 58 degrees would come at 38 if the vacuum canister adds 20...

I can say I stopped reading at the part where the vacuum was connected with the reading he took!!

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post #5 of 11 (permalink) Old May 21st, 01, 08:11 PM
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Dennis hit it right on the head...disconnect the vac advance and plug it to get the proper mechanical advance reading. Unless the distributor has been modified, it probably wont reach full advance until closer to 4000 rpms though.

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post #6 of 11 (permalink) Old May 22nd, 01, 01:17 AM Thread Starter
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DJD,
Are you sure you weren't hidding in my garage .I disconnected the vac and plugged it off ran the R's up to 3000 and the timing was set at 38 degrees.
I backed it down to 30 degrees and everything seems to be good ,except she's a bit of a handful in the wet weather
but I still wonder about that pointer:
again the pointer is off a 69 327(bolts on)
the balancer is stock to the 67 327
the pointer I used was noticably different from the one onthe 350 I pulled out(73year)

does anyone know how many different pointers there are ???

again thanks!
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post #7 of 11 (permalink) Old May 22nd, 01, 05:30 AM
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4-speed, an original 69 Camaro timing cover has the tab spot welded on. They didn't use the bolt-ons until the 70s. 327s and low perf 350s used the smaller balancer, thus closer tab and the high perf engines (302, 350/300s) used the 8 in balancers. Kevin

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post #8 of 11 (permalink) Old May 22nd, 01, 05:31 AM
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4speed,

It's just math!! If your SBC is running better at 30deg's than 38 total advance my guess is the timing tab is wrong. You can pull the plugs and turn the engine over until the #1 cyl. is at Top Dead Center (TDC) and the zero mark on the balancer should line up with zero on the timing tab if it's the right one.

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post #9 of 11 (permalink) Old May 22nd, 01, 06:26 AM Thread Starter
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I'll have to look in to that .
I did drop the dist. in by bring up #1 until it push my thumb off and then bumped it to zero.
the pointer Iam using is a after market chrome one but is different then the stock one on the 350.
so are there more then two bolt on pointers??

If I bump it up to 38 degrees how will I know if Iam starting to dentonant I hear this really bad for a motor ??
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[This message has been edited by 4 speed (edited 05-22-2001).]
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post #10 of 11 (permalink) Old May 22nd, 01, 06:52 AM
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4 speed - there are many different timing pointers, but only two really have different mark locations. Pre-69 (short water pump engines) and 69 and later engines (long water pump engines). There have been many variations of these tabs over the years - depending on balancer diameter, spot welded or bolt on, etc, but the marks should all be in either the one spot or the other. Usually after market tabs will specify pre-69 or 69 and later in the catalog.

Djd - well you really made me scratch my head on the total timing thing . . . so I grabbed my timing light and fired my motor. with my vacuum advance connected total timing is set at 35 degrees (this is where my engine runs best in the 1/4 mile based on trap speeds). With the vacuum advance disconnected I get 23 degrees mechanical advance and at idle I get 11. I guess you can check it with either the vacuum line connected and shoot for around 36* or disconnect it and shoot for 24*.

I guess it's a matter of preference, but most of the guys I've talked to about timing (and articles I've read) are referring to total timing around 36* for a sbc: base + mechanical + vacuum advance = total timing. The full vacuum advance will always be in when the engine is revved to 3000 RPM so the vac advance will not cause a fluctuating or incorrect reading.

Happy rodding!

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post #11 of 11 (permalink) Old May 22nd, 01, 06:57 AM
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BTW if you're setting your timing by looking at mechanical advance you want it all in as early as possible - by 2500 RPM if you can without pinging. 4000 RPM would be way too late for a performance engine IMHO.

There's some real good info on this if you do a search.
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