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| advance timing? https://slantsix.org/forum/viewtopic.php?t=35908 |
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| Author: | plymouthhillsidehemi225 [ Fri Jun 19, 2009 7:26 pm ] |
| Post subject: | advance timing? |
Okay, I know this question is not dealing with a slant, but a 360 in a 79 power wagon, but you guys seem to really know your stuff. The pickup has been coverted to run on propane via a dual fuel carberator that sits on top of the normal gas carb. It seems to really be a "dog" and has absolutely no "pep". This has led me to believe that advancing the timing a slight bit would get it back on par, as everything else (carb, plugs, etc.) has been replaced and/or tuned up. I have no timing light and would like to attempt the guess and check method of tuning, but I wasn't sure exactly how to go about it. My thoughts were to simply loosen the fork that holds down the distributor and turn it either clockwise or counterclockwise ever so slightly, whichever way advances rather than retards it. Now my question is which direction would I turn the dizzy to advance the timing slightly? |
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| Author: | Aggressive Ted [ Fri Jun 19, 2009 9:10 pm ] |
| Post subject: | |
In the direction the rpms increase. That will add more timing. However, using a light would be much better. If you over do it, it may be start to ping under load. |
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| Author: | Doctor Dodge [ Sat Jun 20, 2009 9:02 am ] |
| Post subject: | |
Does the distributor have vacuum advance and is it working? DD |
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| Author: | plymouthhillsidehemi225 [ Sun Jun 21, 2009 10:05 am ] |
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As far as I know the vaccuum advance is working, the truck runs just fine and we do a lot of farm work, pulling hay racks and such with it, but I can tell that it should have a little more snap when you get on the gas. Does anyone have any experience with propane carburetors and how much to advance the timing for that? I heard that that was something you should really do on a gasoline to propane conversion... |
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| Author: | moper [ Mon Jun 22, 2009 9:22 am ] |
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I dont know propane. But, a small block you turn the distributor counter clockwise to advance as the rotor rotates clockwise. If it's mainly a low rpm thumper farm truck, you can add some even without the propane. SOmething like 10-12° initial is where i'd aim for. |
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| Author: | Shaker223 [ Mon Jun 22, 2009 10:32 am ] |
| Post subject: | |
A local autoparts store may have a loaner program. Also, Propane has a higher octane rating than gasoline (103ish) too. That may be some of the slugishness as well. Additionally, you may be able to advance it more (than gasoline) due propane's higher octane. |
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| Author: | FrankRaso [ Mon Jun 22, 2009 9:07 pm ] |
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I would be very careful about advancing timing on a propane engine without a timing light. Just because propane has more octane does not mean that it requires or can use more timing. It can use more initial timing but needs less total timing. A starting point is 14° initial + 14° mechanical = 28° total. It will probably need somewhere in the neighborhood of 14° vacuum advance on top of the mechanical advance for best fuel economy. However, the sluggishness can be from a misadjusted power fuel mixture setting. Ideally, this should be set up with a exhaust gas analyser on a chassis dynamometer. Remember, rich mixtures can lead to burned valves so be careful about how you adjust the power mixture setting. |
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