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  #16 (permalink)  
Old 08-25-2003, 04:01 PM
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I've mentioned this in a few other threads and I got it originally from a thread on this board. Once you modify your engine, the book advance values are useless. The best way I have found to set initial timing on a modified engine (for lowest temp., highest power, no ping, etc.) is with a vacuum gauge. Disconnect your vacuum advance and attach a vacuum gauge to manifold vacuum. Then start and warm your engine and advance the timing @ idle until the vacuum is maximized. Back it down a couple of degrees of advance from this peak and you are set! If you get a little ping, back it down a degree at a time 'til the ping goes away. Works for me every time.

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Old 08-26-2003, 06:40 AM
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when you set the timing to to 22 degrees did you have a hard cranking start or did it start easily?

I have the vacume adv hooked up to the frt of carb (which would be intake manifold). I use the the car for just street use but
occasionally use it for the strip.

Last edited by bad502; 08-26-2003 at 06:49 AM.
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Old 08-26-2003, 07:03 AM
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Quote:
Originally posted by bad502
when you set the timing to to 22 degrees did you have a hard cranking start or did it start easily?

I have the vacume adv hooked up to the frt of carb (which would be intake manifold). I use the the car for just street use but
occasionally use it for the strip.
I don't see any post that suggested you use 22 degrees for your initial timing. Is that with the vacuum line connected or with it dis-connected and plugged? It will probably be hard to turn over the engine with that much initial advance.

Try setting your initial timing to 16-18 degrees with the vacuum advance line disconnected and plugged. After you have set the timing, hook the vacuum advance line back up.
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Old 08-28-2003, 11:44 AM
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ignition timing

I set the initial timing at 16 and changed the springs in the dist. to give me a total timing of 34 degrees. now when I hooked the vacume adv. back up it bump up the timing a consider amount.
do I need to adjust the vacume adv. so that it does not pull that much out or what does it have to be so that I can set it corectly.
I'm learning how to do this so please be understanding.
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Old 08-28-2003, 11:59 AM
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You are using the 'full' vacuum port. This is why the timing and the idle RPM increases when you hook the hose back up and is normal. Just lower the idle speed with the stop screw on the carb throttle linkage to the RPM you want the engine to idle at. If you have an automatic trans, set the idle RPM with the trans in gear. The idle speed will be higher when the trans is in Park.

i.e. My vacuum line is also hooked to the full vacuum port. Idle in Park is 850 RPM. Idle in gear is just under 700 RPM.

Some will suggest that you hook the vacuum line to the 'ported' vacuum fitting. Try it. Then switch it to the full port and try it. Decide which one works best for your combo. What you are looking for is the best take off from a stop.

Last edited by Frisco; 08-28-2003 at 12:16 PM.
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Old 02-18-2006, 07:54 PM
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If you had your e/mail address accessable for others here on the board, I would have already sent info for you on the distributor.

If this is a crate 502 using a carb, and the STOCK CRATE HEI DISTRIBUTOR, then please contact me, I have 6 pics of how to make the stock dist work the right way.

If not, I can help you do it the right way, no mater the distributor type.

In the subject box for the e/mail, please use "pics, HEI redo". Disregard the spam filter message, when I send pics to you, e/mail won't be spam blocked again

sparkman451@earthlink.net.
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Old 02-20-2006, 06:57 PM
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Chevy 383 - I set my timing to give me a total advance of about 36* at about 2800 rpm. This is with vacuum disconnected, and using aftermarket distributor springs. Once I set total advance, I don't care were initial is.

I know I am getting some centrifugal advance at idle due to the softer springs, but it doesn't matter.

I then check what the maximum vacuum advance @what ". This is best done using an outside vacuum source - MitiVav is what I use. Check your engine vacuum at idle. For performance, vacuum can should bring in all vacuum advance about 2" less than idle vacuum. Total advance from the vacuum can only should be about 14* to give a total of about 50*. Don't believe me, check Vizards books.

With the right can, I hook the vacuum up to manifold vacuum. Initial advance on the timing light is in the 30+* range beause of the full 14* vacuum + the initial = the amount of centrifugal I am pulling in.

Engine is 10.25CR aluminum heads, CC XE274 cam, and runs on 89 octane gas without ping. May even run on 87, but I have no guts to try it.

No problem starting, as starting only sees initial timing + any little centrifugal it sees at cranking speed.
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