Amc 304 engine questions - Page 2 - JeepForum.com
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post #16 of 22 Old 02-25-2013, 07:33 PM Thread Starter
Hbryant123
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1979 CJ7 
 
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I read through the oil pump thread! thats a well made thread! that is defiantly something i can do for spending very little, i seen some oil pump rebuild kits for around 20$ on ebay. why would i only wanna replace the rod bearings? shouldnt i do the mains also? Something i was looking at today was after i fire up the engine and lightly rev it it makes almost a rattling sound. Im thinking its related to the oil pump not properly oiling the engine. What are some places i canget a cheaper mechanica oil pressure guage?

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post #17 of 22 Old 02-27-2013, 08:19 PM Thread Starter
Hbryant123
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I did a compression test today.1=90,2=90,3=75,4=80,5=80,6=40,7=90,8=90.
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post #18 of 22 Old 02-28-2013, 05:48 AM
timgr
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You want to patch up this engine; this means just replacing the parts that will improve the engine the most. You will need to take the engine out of the car to replace the main bearings. And the main bearings wear less than the rod bearings. The rod bearings are continually hammered by the cylinders firing, so they typically see the most wear, esp. when the oil pressure is so low.

Do you know about Plastigage? I would fix up the oil pump, and see what oil pressure I had. Then I would Plastigage the rod bearings to see if there is significant wear.

Your compression test numbers indicate that the rings are worn and the engine is simply tired. This agrees with your earlier statement that there is a lot of blow-by. Number 6 is pretty bad - you may have a leaky exhaust valve on that cylinder. If you replace the rings and don't do the valves, that may become a problem. Usually an overhaul includes the rings and the valves, because both are needed to maintain compression.

Try AutoZone for a cheap mechanical OP gauge.

1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D
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post #19 of 22 Old 03-01-2013, 08:55 PM Thread Starter
Hbryant123
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What is a plastigage?? Since the kit i am interested in comes with a new melling oil pump ill just install it when i do the overhaul. I am thinking the uneven compression is causing it to not idle the best either. After the rebuild i am going to switch to a msd cap, rotor, plug wires and also new plugs, i have already switched to the ford ecoil. For the machine work ik a local shop that can do the heads, what all will they do to them? mill them even?
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post #20 of 22 Old 03-02-2013, 07:53 AM
timgr
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Google is your friend - https://www.google.com/search?q=plas...=hp&channel=np

The only thing included in a "new melling oil pump" for this engine is the gears and some gaskets. The body of the oil pump is the aluminum timing cover. Aluminum is softer than the steel gears, and that's the part that wears out. Look at the link I posted above.

I suggest you read the chapter in this book about cylinder heads - http://www.amazon.com/Engine-Builder...lders+handbook - the book is cheap, and has a lot of good info. Read it cover to cover, if you can.

1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D
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post #21 of 22 Old 03-02-2013, 08:40 AM
82JeepCJ7
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Toss a new mid plate in the oil pump along with a new set of gears etc. Use Jeephammers method of getting the surfaces flat and call it good.

Beat it to fit, paint it to match!

Wheel, Wrench, Repeat.
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post #22 of 22 Old 03-02-2013, 08:53 AM
timgr
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Quote:
Originally Posted by 82JeepCJ7 View Post
Toss a new mid plate in the oil pump along with a new set of gears etc. Use Jeephammers method of getting the surfaces flat and call it good.
Link?

Never mind - here's the link: http://www.jeepforum.com/forum/f8/am...hread-1050446/

The point of 82JeepCJ7's post is correct. Fix the oil pump first. IMO there's no reason to buy a mid plate if you refurbish the oil pump cover. The mid plate just replaces the newly honed surface of the oil pump cover. Save time and effort with the mid-plate, or save money by refurbishing the oil pump cover.

IMO replacing the gears is pointless, in most cases. Accomplishes nothing except to make you feel better since you are using new parts. Just get the gasket. BullTear offers the gasket in a couple of different thicknesses - the thin gasket could save a lot of time lapping if the clearance is very sloppy. http://www.bulltear.com/catalog/prod...roducts_id=208

The important thing is to measure the clearance, either with feeler gauges or with Plastigage.

Refurbishing the oil pump may not solve your oil pressure issues. But it may, and you won't know until you do it.

1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D
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