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I love Wendy's Frosty drinks!

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FSJunkie View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Jan/14/2018 at 4:30am
You've probably realized this is more of a slow build thread than a questions or help thread. I just thought we would all get some entertainment and good conversation out of this

I have it apart as far as I need. It has never been apart before other than the valve cover gasket, intake manifold gasket, and thermostat having been replaced, and it is the original engine to this Eagle with verified original mileage. 

Several things were in extremely good condition and astonished me for being a 166,000 mile engine:
  • The head had never been off for a valve job, and yet all the valves still sealed perfectly. Valve face, seat, and guide wear remains unknown, but they are still sealing. 
  • The original timing set had a very loose chain, but the sprocket teeth (including the plastic ones) were not gouged or exceptionally worn. I simply cannot believe it had not completely failed by this point.
  • The cylinder bores had very little wear. So little in fact, that there is no wear ridge at the tops of the cylinders. 
  • It also ran perfectly. Perfect compression. Ran silent. 
These things astonished me, because my 232 that I rebuilt at 116,000 miles had valves and seats that were worn out and starting to leak, a timing set with gear teeth very worn and gouged, and cylinder bores so worn that the ridge at the top of the cylinders would practically cut your finger and it required a .040" overbore to fix. This 166,000 mile 258 is probably in better shape than my 232 was at 50,000 miles. Then again, that 232 spent its whole life in dusty Kansas and came to me without a PCV inlet filter while the 258 spent its whole life in San Francisco and appears to have always received proper maintenance, including the PCV filter. 

However, there are some ugly things in the 258, mainly signs of cooling system neglect and overheating:
  • Heavy carbon and sludge buildup everywhere. Nearly 1/2 inch of gunk plugging up oil drains around lifter bores. 
  • A failsafe 160 degree thermostat stuck open, indicating overheat condition. 
  • Heavy cooling system corrosion from lack of flushes, including to head gasket, that may have contributed to mixing coolant into the oil. I worry about the condition of the freeze plugs. 
The plan:
  1. Check head for flatness and cracks. Perform valve job. 
  2. Dig/scrape/dissolve/flush as much gunk and goop out of the short block as possible without removing it from the car for complete teardown or removing the oil pan. 
  3. Inspect cam and lifters. Install new if excessively worn.
  4. Install new water pump. 
  5. Install new timing set. 
  6. Install new proper thermostat.
  7. Maybe install new freeze plugs. ?????
  8. Clean.Everything. This engine is filthy. 
  9. Reassemble engine using new gaskets. 
  10. Run it for a few thousand miles with high detergent oil to finish dissolving and cleaning out the gunk. Change oil filter often. 
It should be good for many more miles after that. 




Edited by FSJunkie - Jan/14/2018 at 4:33am
1955 Packard
1966 Marlin
1972 Wagoneer
1973 Ambassador
1977 Hornet
1982 Concord D/L
1984 Eagle Limited
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purple72Gremlin View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Jan/14/2018 at 7:15am
If the cooling system is full of gunk...taking out the freeze plugs will allow you to get alot of gunk out to clean it. But with the engine in the car, well..it's not easy to get them out or put new ones in....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jan/14/2018 at 11:13am
I'd try to get the freeze plugs out and replaced anyway. With the head off you can get to all but the one in the back (which is under the bell housing). There used to be copper or brass plugs that you tightened with a screw. Those would be easy to put back in. I wouldn't use the rubber type, they harden and shrink with age, you'd have to tighten every couple years or so and eventually replace them. Good for quick fixes though.

No ridge on top can be deceiving!! The long stroke six doesn't wear much at top, but wears 2-3 times as much near the bottom of the bore due to the side to side action down there. Use a bore gauge and check near the bottom as well.

About 74 or 75 (may have been as early as 72?) AMC started induction hardening the combustion chamber side of the head instead of using valve seat inserts. This hardened both valve seats, but just a few thousandths deep. The valve seats last a long time, but more than one grinding may go through the hardening, requiring an exhaust valve seat insert for long life.
Frank Swygert
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