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Old 03-09-2004, 04:08 PM
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smallblock to advanced

Hello everyone. I was on here before and asked if anyone would let me know why when I plug in my vacuum advance I end up with way to much advance at 3000 rpm. At idle its set about 18-20 then at 3000 its at 36. When I do connect the vacuum advance I end up way at 60 deg at 3000. I plugged it off, but I don't know if I'm losing out at all this way. Why is my vacuum giving me so much advance. Please help. Thank You

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Old 03-09-2004, 04:17 PM
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Dissconnect your vacume advance. Your vacume port on your carb should have 0 vacume . Set your timing at mabee 12 degrees, then hook up your advance.. that should be it.. oh, yea set your idle where ut is supposed to be before you set the timing. that would help.
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Old 03-09-2004, 04:24 PM
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advance

thanks curtis, at 3000 rpm's at 12 deg initial I'm still ending up in the 50's before tdc with the vac. connected
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Old 03-09-2004, 04:42 PM
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What are you using to measure 50 degrees? Timing tape? If so, is it the right tape?
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Old 03-09-2004, 04:48 PM
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Remember that you have the mechanical advance working too. ( hopefully anyway).

At 3 grand, the mechanical weights should be full on. I got my 350 set at 12 initial, plus another 22@2800 mechanical, plus 12 more with the advance hooked up for a total of 46 and it runs fine and does not ping on 87 gas. Its not a high compression, but close to 9.2 and pretty old right now.

You can get weight kits for the mechanical advance to taylor the mechanical curve, plus you can get adjustable vacuum advances too.

Mark
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Old 03-09-2004, 04:53 PM
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You set the timing correctly when you first posted. You always dis-connect the vacuum advance hose from the vacuum cannister and plug it when setting the timing on a carbureted engine. I would suggest setting the initial to 10-12 and the Total Mechanical at 32-36 all in around 2500-2800 RPM.

You have the vacuum hose connected to the "FULL" vacuum source and when you re-connect it and check your timing again what you are seeing is correct and normal. Keep in mind that when you go to WOT the vacuum drops to "ZERO". Also as the load on your engine increases the vacuum drops. A vacuum advance cannister actully both advances AND retards as the demands on the engine increase and decrease.

Some folks will suggest that you hook the vacuum advance hose up to the "Ported" source. I have found that my combo works best using the "FULL" vacuum source.

A simple test for what works best for you would be to hook the vacuum advance hose to the Full source and from a dead stop go to WOT. Then switch the vacuum advance hose to the Ported source and repeat the test. Whichever works best for you is the one to use.

ENJOY!!!
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Old 03-09-2004, 04:58 PM
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timing

I'm using a timing light with the dial. My curve in the distributor is around 20deg which ends up at 36 at 3000 then when I plug in my vac. it goes up approximately 13 deg more than 36 deg

Hey Mark thanks for the reply I was always told to stay around 36deg total, but it's not working out for me so far. A machine shop said I was detonating to bad with that much so they disconnected my vac. advance and now I'm around 36deg without vac. advance. I found tdc on my balancer and it's in the right spot. Thanks again
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Old 03-09-2004, 05:20 PM
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Some clarification.

1.-There should be zero vacuum at the Ported source at idle if the carb is adjusted correctly. As the throttle is opened the Ported source will show an increase in vacuum. If you set the timing with the vacuum advance hose dis-connected and plugged and then hook the vacuum advance hose back up to this port the timing should not change at idle. It will increase when under driving (load) conditions.

2.-There will be vacuum at the Full vacuum source at idle. This port is also where you would hook up a vacuum gauge to adjust the air/idle screws for the highest vacuum at idle. When you go to WOT under driving (load) conditions this vacuum will drop to zero.

If you set your timing with the vacuum advance hose dis-connected and plugged and then hook the vacuum advance hose back up and are using this port the timing will show an increase and the idle RPM's will also increase some.
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Old 03-09-2004, 08:09 PM
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Good answers so far, but, A. what compression ratio are you running 10:1 or more on pump gas and some detonation is a part of life. B. If you are playing with a 10 + yr old HEI I would junk it and buy a new Mallory HEI or Unilite, OEM HEI units tend to get a lot of play in the advance mechanisms over time. I know the Motorcraft units do.
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Old 03-09-2004, 08:51 PM
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I dont know,maybe somebody has done something to it to run it only on mechanical. Ive had my best luck at 34/36 total.
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Old 03-10-2004, 01:03 AM
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Re: smallblock to advanced

Quote:
Originally posted by tweaked
. at 3000 its at 36. When I do connect the vacuum advance I end up way at 60 deg at 3000.
Sounds like your advance can is overdoing it. Find a can with no more than ~15* in it.
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Old 03-10-2004, 01:08 AM
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engine

check that the weights inside your dizzy are fitted correctly
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Old 03-10-2004, 04:59 AM
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Your Dizzy??

Love it....never heard it called that before...............
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