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ccowx
AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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You can tackle this in two ways. You will find proponents for either, but it is up to you how to go about it.
-Option A is to restrict the mechanical advance to around 20 degrees. Then you can set the idle at around 15 BTDC as Badanov suggests. Hook the vacuum advance to ported vacuum and adjust the cruise vac advance to what the motor likes. -Option B is to set the idle timing at something around 5-8 BTDC with a total of around 34-36 degrees. Then get a vac advance can that will give you an extra 10 degrees or so at your idle vacuum. Hook the vac advance to a manifold vacuum source. Make sure that your advance can also gives you some advance at cruise rpms. To test how your engine/trans will react to this, disconnect your vacuum advance and twist in some extra timing. Then try dropping it into gear and see what happens. Either way, I would suggest the distributor sticky at the top of this "V8 repair message board" for good information on both your mechanical advance and also specs for the vac can. Good luck! Chris
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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If I remember correctly my 1969 343 Ambassador automatic would go to
no more than 1150 RPM mashed with the brakes on (stock 4bbl motor). |
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Gremlin Dreams
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AMXAL
AMC Nut Joined: Feb/19/2012 Location: IL. Status: Offline Points: 324 |
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So one fact I forgot to mention, I did change the distributor, I am using the one from my 74, 401 Javelin, and it has been fitted with a Pertronics unit. I know AMC used different Distributors through the years, is this a potential problem. The Javelin distributor was working fine in that car..I changed it out for an HEI unit.
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ccowx
AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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Nice car on the 401 Javelin! As for it's distributor, it can be made to work in the 343. They are all set up for a certain vacuum/compression/carb etc and may or may not work in another motor without tuning. Again, go to the sticky on distributors at the top of this message board. It will show you how to see what your dissy is and how much advance it has, what vac canister, etc. Then you can begin deciding how you want to go about tuning it or if it will work fine as is. The pertronix set does not make any difference, timing wise.
Chris PS: OK, I had to look! The 401 dissy should have 1112215 or 1112112 on the outer edge. If it is the stock 401 unit it will have 34 degrees of advance, maybe 5 or 6 less if it still has the rubber bushing on the advance peg.
Edited by ccowx - Oct/09/2015 at 12:07pm |
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AMXAL
AMC Nut Joined: Feb/19/2012 Location: IL. Status: Offline Points: 324 |
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Chris...sounds like the 401 dist should not be an issue based on what you said before, soall that I need to do is find a vacume can that can do another 10 degrees...right? I am guessing I use an adjustable one and tune it in?
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ccowx
AMC Addicted Joined: Nov/03/2010 Location: Yukon Status: Offline Points: 3510 |
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How to set timing can be an impassioned discussion around here, so I am just presenting a couple of possible suggestions. Lots of ways to skin this cat!
The easiest might be to use the stock 401 dissy that is in it, assuming that is what it actually is. I would make sure it has the rubber bushing on the advance peg, so you should be getting around 28 or so degrees mechanical advance in the distributor. You might even want to buy a Mr. Gasket 927G recurve kit, since it has both a bronze bushing for the peg and also some weights and springs that might be handy tuning items later on. Set the initial timing at around 5-8 degrees BTDC. This is not enough, but the vac advance will crank that up to around 15-18 or so. Your idea of an adjustable vac canister is a good one. Hook it up to manifold vacuum, such as a t-fitting off the power brake or transmission outlets. Now adjust it so that it pulls around 8-10 degrees of timing both at idle and also at cruise. That is one method of doing it, especially if you don't want to be modifying the distributor by welding in advance slots and such. Option A above will also work well, though it will require work to both the mechanical and vacuum advance. Chris
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toolmanxiii
AMC Addicted Joined: Oct/16/2010 Location: Moncton Canada Status: Offline Points: 1384 |
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I had a look at the dizzy sticky... what I don't see is the different advance's used for Standard and automatic. I know the Vacuum advance has I different pull rate between auto and standard . also different weight and spring rates .
I'd call Tech support for the cam and see what they say . Give them all the info you have on engine trans carb torque converter etc. Isky was more than happy to help me with the timing on my 360. |
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71 360 Hornet sst 83 2wd 360/727 Eagle wagon (crashed)
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