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I have begun the rebuilding of the 4.2 engine from my 77 CJ-7 barn find project. My local NAPA store in Buckeye, AZ has a reputable engine shop attached and run by an family friend of my wife. Its good to have friends with years of experience to help. I opted for NAPA's deluxe master  rebuild kit which is a good value when you get it all at once.

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I was pleased with how clean the hot tank process got my dirty block and sheet metal. I had given up on scrubbing and even the pressure washer didn't work well. After taking measurements it was decided to go with the .030 re-bore.  My sharp eyed engine man noticed that the oil bypass valve retainer had damage to the shoulder that fits into the block for alignment. I think I understand how this valve works and felt this damage would compromise the integrity of the valve. I am  not sure how the damage occurred other than  forces applied during removal or installation. Luckily there is a good bit of info about the valve in my Jeep CJ re-builders manual by Moses Ludel.

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A trip to my local AMC junk yard did not yield one. I'm not sure if this part is still stocked anywhere. I decided to see what I could do with my MIG welder and I think I succeed but I would still use a new or salvage one if I can find it.

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Next I installed the nice brass plugs that come with the kit and the oil passage plugs. The new cam is standard OEM grind and fit nicely into the new bearings installed by my shop. I'm not sure exactly what holds the cam in place on this 77 vintage engine. Chain? Lifters? Distributor? All three? My engine does not have the spring and Pin thing on the timing cover that Ive heard about on later engines. My jeep project had signs of good regular care by one owner. My crankshaft was still within specs for a polish only and standard bearings. 

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The crankshaft is now installed after verifying still in specs on oil clearance with plasti-gauge.

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Nice work, Stuart...Did you polish the crankshaft?  Looks good...No regrind and balance?  Inline sixes are very tolerant of balance, OEM cranks and flywheels generally do not create an issue.  I usually grind 0.010"/0.010" undersize and balance the reciprocating parts.  Match weighting helps, too.  Not sure if any of this is in your plan...

I'll look through my OEM Mopar parts for the 4.2L projects.  I may have a valve retainer.  The original part number is J3173225.  The number may have been updated later by Mopar.

Moses

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Moses,

No regrind. Just a polish. I cant afford to get too carried away, hopefully I'll be ok. My 77 jeep factory shop manual showed up today, lots of good info in there. I got the timing chain on today. I fumbled around with that quite a bit but got it clocked correctly. I have wondered if Mopar has a stock of the older jeep parts like the valve retainer. Ill have to check.

Stuart

 

 

 

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Stuart...I'll look for a retainer in my boxes of NOS Mopar parts and get back...I am doubtful that Mopar has any interest in this part (J3173225) or AMC era engines.  Unlike us, they focus on new models and late technology...This part is officially discontinued, though I found a package of four (NOS) at eBay by running the part number.  That particular ad is in Spanish.

I will let you know if my boxes of parts include a retainer...

Moses

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Stuart...I messaged a note your way...Found a J3173225 Retainer, brand new in the original Mopar bag...I have two (2)...See my message.  Pleased that you're working with a '77 factory service manual, that's first generation information..Moses

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I'm sending the Retainer your way, Stuart...The 4.2L/258 engine looks good, always easier to install the main seal with the block upside down.  Nice attention to detail!

Moses

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