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AMC 360 tuning

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glennsea View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote glennsea Quote  Post ReplyReply Direct Link To This Post Topic: AMC 360 tuning
    Posted: Feb/23/2010 at 10:10am
I have a 360 that was rebuilt and running great. I had some issues a few weeks ago where it would not run. This turned out to be a short in a harness.

During the troubleshooting I rebuilt the carb and changed the timing and it does not seem to habe the power as before.

The carb is a holley 600 cfm. When I rebuilt it I did the factory needle setting and float settings. While it was running I reset the idle and adjusted the floats where fuel trickles from the view port hole. I didn't change any linkage settings yet.

I looked all over the place for timing advance settings. I hae several manuals covering the AMC 360, have read many posts from the Internet, etc. and there can be a wide range for the numbers. This eng is from a later model Javelin.

Do factory timing settings apply to a built engine? I started at 5deg BTDC, then 8, 10, now 15. Or max performance it is my understanding that you advance until ping then bach off. Is that for WOT performance? I want the powerlower, say from stop to around 4000 rpm so do I adjust timing diff for that?

The engine sounds like it is going it just does not feel like it. With some of the setting it wanted to shut off. The dist is point nd some were just replaced.

1st feels ok, 2nd feels better when I get over 2000 rpm, 3rd feels pretty good over 2000 rpm, 4th is a dog. It is slow to get rpm's up and just feels like there is no power until I get up in rpm's. So in city driving I may go to 4th in a 45mp zne but may be driving faster and I don't have the power. If I go itil it does I am going too fast.

I am new to perf tuning carb'ed engines like this but view this as a great learning experience but I feel like I am not progressing. I don't want someone else. To fix it.

Should I keep advancing? Could there be something else wrong. Should I look at setting the carb linkage?
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BassBoat View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BassBoat Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 10:51am
Factory settings only apply for emissions, IMHO.  The rule of thumb for advance until it pings is a good one.  With a mild low compression 360 a better rule might be to advance until it won't start hot.  More initial advance will improve low end power.   I would try 20 right away, maybe more.  Assuming you are still running vacuum advance, eventually you will get to a point where at low speed just putting along at 40 or 45 miles an hour you will get a slight surge that will go away with just a bit more throttle.  That is another indication that you finally have all the advance you can stand.  You should disconnect the vacuum advance when setting the timing. 
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Rebel 327 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rebel 327 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 10:53am
Did you set the timing with all the vacuum ports blocked?  Is your vacuum advance working?  Are you still using points?  What happend when you retard the timing?  Could you have put a gasket in the carb turned 180' and blocked a port?  etc...
Rebel 327 4-speed
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glennsea View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote glennsea Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 11:08am
I am getting somewhere now. I put the light away and advanced off the scale. I noticed as I advanced it was idling better and better. When it started getting rough I backed up until it sounded good. Holy cow this thing feels good now.       

I think my idle is too high now, around 1100 rpm. Where should I be at?
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glennsea View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote glennsea Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 11:24am
It is hard to start so I am backing down until it's easier. Idle is going down at the same time.
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glennsea View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote glennsea Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 12:14pm
How long would you have to wait until it's easy to start again?
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BassBoat View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BassBoat Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 2:48pm
usually the heat soak is on the order of a half an hour or so.  But it did run good with the timing advanced, other than not wanting to start does it seem like its got some zip now?
now that you are on the right track, there are some things to work out like using lighter springs to get the advance in sooner, and maybe a different vacuum canister to give you a timing boost without cranking the initial quite so far. 
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glennsea View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote glennsea Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 3:46pm
It felt really good advanced pretty far but was really hard to start(compression right?).  I kept backing it down until it would turn over fairly easy and left it like that for a while.  I noticed that when cold it turned over great but didn't want to start like it was not getting spark right.  I made another small adjustment and it corrected that. 
 
So I guess I can make a mark for a higher advance number and set it there and then if I go somewhere and need to start back up quick have anothe mark retarded.  I guess I will get a lot of looks going under the hood all the time.
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forest View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote forest Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 3:54pm
got a timing light?
setting guys out by car lengths....
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glennsea View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote glennsea Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2010 at 6:38pm
Yea, I have a light but as I mentioned earlier I am way off the scale so I would have to make an extention stick on scale to see where I am at. Just doing by sound and feel at this point.
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