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Timing Chain Questions ?

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TinMan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TinMan Quote  Post ReplyReply Direct Link To This Post Posted: Feb/15/2010 at 8:48pm
Heh.
Well, depending on how far back you go, 3+ valve engines weren't very common in the US. Look at the majority of the older American i6's, and then look at the older Nissan and Toyota i6's. Same with overhead cams and dual overhead cams.

Ever see a 5 valve Audi/VW engine? When you compare them to their 4 valve engines, it's like they just engineered another one in there just for kicks or something, looks really out of place and they make about the same power as the 4 valve equivalents.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote poormansMACHINE Quote  Post ReplyReply Direct Link To This Post Posted: Feb/15/2010 at 9:01pm
Each had different goals for their engines. For the US market, the 6 was the bottom of the line allowing you to go from point A to B.
In overseas markets, the 6 was a step up as was our 8.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 6:55am
Got me! I doubled valve instead of cylinder count, obviously. 
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 7:29am
in any case, the two very low compressions are a concern........ if adjacent, like said, head gasket blown is possible, or it's possible it's a coincidence they are next to each other.
In any case, any time you have more than a 10% difference, you have an abnormal compression pattern and should be suspect...............
You can do a leakdown check. You can pull the valve cover and see what's operating and what's not, and get a close check on the valve timing that way as well, depending on the tools you have and the specs you have available.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote 258guy Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 1:14pm
Thanks everyone for the input. I did pull cover, everything looks ok ? A 3rd generation  AMC dealer service manager told me that he saw a lot of 258's jump time and run like sh-- ! The part that has me thinking is what the previous owner told me, "All of a sudden it just started to run bad" so i parked it. Can it be off just a tooth and cause the low compression ?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 2:07pm
Not on just two cylinders.......... a blown head gasket could be sudden and impact 2 cylinders that are next to each other (because I can't spell adjacent, I used that phrase instead)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1970390amx Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 2:28pm
as stated before, if the cam timing is off it will affect all cylinders the same. the two that are low need to be addressed. A leakdown test can determine what the cause of low compression. If it has bad rings or valve sealing problems the condition of the timing chain is not important. If you start it and check the timming is it close. if it is the timing chain probaly has not jumped, unless PO has messed with it in an effort to make it run better.
1970 390 4speed Bittersweet shadow mask AMX
1970 Amx missing most everything, or in a box
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 258guy Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 5:20pm
Thanks Clap I think I must have a blown head gasket, color of inside rad tells me it got hot at one time. Angry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote poormansMACHINE Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 5:30pm
What color are you seeing that says overheat??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Feb/16/2010 at 6:38pm
Originally posted by poormansMACHINE poormansMACHINE wrote:

What color are you seeing that says overheat??


Lots of pretty colors - a virtual rainbow!

LOL - white milky could mean trouble.
Rusty means it's simply old and hasn't been changed in years and the anti-oxidation chemicals are toast.

If it's got a horrible bitter smell out the tail, that's not a good thing, Martha.
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