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 Post subject: slight engine problem
PostPosted: Wed Mar 16, 2011 8:08 am 
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TBI Slant 6
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Joined: Fri Jul 30, 2010 12:01 pm
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Location: Arizona
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SO, i just changed my timing chain, because the old Original gear was one step from death, the chain was loose enough that it could jump from one tooth to the next without troubles.

now my problem is as follows:

we adjusted the Timing to TDC as the blue book of 1974 stated to do, we drove it for a bit, idled smooth, ran great, except for serious lack of power, AND dieseling when turned off, even in reverse with my foot pressed on the break.

now i have read that it could be a few things, timing and carb being among the top reasons, but i was hoping for some more opinions.

any help would be appreciated.

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74 plymouth duster, 225 single barrel slant six


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PostPosted: Wed Mar 16, 2011 10:15 am 
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EFI Slant 6

Joined: Sun Jun 15, 2008 12:03 pm
Posts: 363
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Quote:
SO, i just changed my timing chain, because the old Original gear was one step from death, the chain was loose enough that it could jump from one tooth to the next without troubles.

now my problem is as follows:

we adjusted the Timing to TDC as the blue book of 1974 stated to do, we drove it for a bit, idled smooth, ran great, except for serious lack of power, AND dieseling when turned off, even in reverse with my foot pressed on the break.

now i have read that it could be a few things, timing and carb being among the top reasons, but i was hoping for some more opinions.

any help would be appreciated.
If your distributor isn't one of those that has this huge leap in timing right off idle, then 0 degrees is about 12 to 15 degrees retarded, which would cause extremely low power, dieseling, poor idle and consuming gas like a fiend.


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 Post subject:
PostPosted: Wed Mar 16, 2011 11:08 am 
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Turbo Slant 6

Joined: Fri Sep 09, 2005 9:51 am
Posts: 855
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Lately I've had a couple of harmonic balancers slip between the inner and outer parts, throwing the timing mark way (~120 deg) off. You might want to recheck the TDC mark mechanically.


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 Post subject:
PostPosted: Mon Mar 21, 2011 1:46 pm 
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TBI Slant 6
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Joined: Fri Jul 30, 2010 12:01 pm
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Location: Arizona
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so we ruled out compression i hope... if a high of 135 PSI and a low of 119 PSI is correct on a 225 Slant.

but also we adjusted the carb... made it richer and it ran better but still have a distinct lack of power, so what we are left with is vacuum and timing, i hope we are not off a tooth... i really hope we arent

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74 plymouth duster, 225 single barrel slant six


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 Post subject:
PostPosted: Mon Mar 21, 2011 2:05 pm 
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Guru
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Joined: Mon Oct 14, 2002 4:32 pm
Posts: 4880
Location: Working in Silicon Valley, USA
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Pull the valve cover and check the overlap event at TDC Exhaust stroke.
Overlap should be even or a little advanced over TDC. (More detail below)
DD
Quote:
The trouble with most timing sets is that they only go on one "right" way and if you take the time to degree the cam, the "dot-to-dot" position may be off optomum by a good amount. A cam that is not optomized can really hurt engine performance.

Funny... I used to spend a lot of time degreeing in cams. Setting up the degree wheel and pointer, making many engine revolutions, pen & paper notes, checking different offsets...

These days I degree most cames in about 15 minutes, just because all my tools are set-up and I know what to look for. I don't use the special bushing most of the time, instead I mill the top gear's cam pin hole "oval" and slip-in a spacer to move the cam forward or backwards, the needed amount.

The quick check anyone can do, to ensure a "centered" cam is to look at the overlap event (both valves open) at TDCE, to make sure it is evenly split or a tad bid advanced over true TDC. This is always a good double-check, to be sure that you "lined-up the dots" correctly. (or that the dots are in the right place, for that matter )
DD


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 Post subject:
PostPosted: Tue Mar 22, 2011 1:52 pm 
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TBI Slant 6
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Location: Arizona
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okay thanks DOC i will probably do that this weekend... i get paid so might as well pick up the gasket

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74 plymouth duster, 225 single barrel slant six


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 Post subject:
PostPosted: Thu Mar 24, 2011 1:25 pm 
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TBI Slant 6
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Joined: Fri Jul 30, 2010 12:01 pm
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Location: Arizona
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so say i find a vacuum leak... whats the quickest/easiest/cheapest way to find it?

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74 plymouth duster, 225 single barrel slant six


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 Post subject:
PostPosted: Sat Mar 26, 2011 6:13 am 
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EFI Slant 6
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Joined: Mon Aug 24, 2009 5:19 pm
Posts: 310
Location: New Hampshire
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Use a can of carb cleaner and spray around the carb base-intake to head gasket-any and all hoses (full length) that come off the intake manifold. If the idle speed changes you found a problem area.

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Taking care of 57 300C conv,48 T&C conv. Missing my 67 GTX and 36 Ply coupe


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