AMC 258 Engine Interchange question - Page 2 - JeepForum.com
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post #16 of 28 Old 07-02-2010, 07:30 AM
jeepwhore
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If it's just a tapping or ticking it's more than likely just a sticky lifter. Mine has had one for a long time and, like yours, it doesn't burn any oil and has good oil pressure. I did have it progress to a bad knock after it sat for a few months following a rollover but that turned out to be carbon build up on top of the pistons. A little water and diesel down the carb followed by some 3500 rpm revs and it blew black, purple and blue out the tail pipe and no more knock.


'84 CJ-17: 17" stretch, locked Toy axles, 5.5" lift, FI, AX15, D300 w/twin sticks, boatsides & junk.
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post #17 of 28 Old 07-02-2010, 07:41 AM
82JeepCJ7
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I've also heard that putting a cup of ATF in the oil and running it for a short time then changing the oil will help free up a sticky lifter.
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post #18 of 28 Old 07-02-2010, 11:08 AM Thread Starter
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Very interesting! Thanks guys, i`ll let you know if any of these awesome tricks work. This Jeep has been sitting for a while and the previous owner also didnt drive it on a regular basis, though he took longer trips often.
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post #19 of 28 Old 07-02-2010, 11:14 AM Thread Starter
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If all else fails maybe i`ll get a video of the sound!? I know these things are difficult to hear over a video but cannot hurt.
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post #20 of 28 Old 07-02-2010, 11:29 AM
Mike Romain
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To start, a "long block" means the complete engine including the head so the size of the head bolts is meaningless. The 79 engine will swap right in and you can put your computerized intake, exhaust and carb right on it. Though the 79 carb may be a better one, if it is a 2 BBL Carter.

Do yourself a large favor and read about the nutter bypass so you can just set the computer carb up like a 79 carb and have a sweet 25% seat of the pants boost in power. How to - Nutter Bypass - JeepForum.com This bypasses all the computer controls so the engine just runs off the ignition module like the 79 does and is easy to do. That way you can use the 79 distributor and carb.

The knock in the old engine could very well be an exhaust leak, they are notorious for snapping off the last exhaust manifold bolt or just plain coming loose.

Mike
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post #21 of 28 Old 07-02-2010, 12:03 PM Thread Starter
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Quote:
Originally Posted by Mike Romain View Post
To start, a "long block" means the complete engine including the head so the size of the head bolts is meaningless. The 79 engine will swap right in and you can put your computerized intake, exhaust and carb right on it. Though the 79 carb may be a better one, if it is a 2 BBL Carter.

Do yourself a large favor and read about the nutter bypass so you can just set the computer carb up like a 79 carb and have a sweet 25% seat of the pants boost in power. How to - Nutter Bypass - JeepForum.com This bypasses all the computer controls so the engine just runs off the ignition module like the 79 does and is easy to do. That way you can use the 79 distributor and carb.

The knock in the old engine could very well be an exhaust leak, they are notorious for snapping off the last exhaust manifold bolt or just plain coming loose.
Thanks alot, in the event of an engine swap this information is priceless. I will check out the nutter bypass - having not read it, would that mean ditching my HEI? I dont have any of the stock intake stuff from the 79 but do have the dist.
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post #22 of 28 Old 07-02-2010, 01:36 PM
Mike Romain
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Originally Posted by featured View Post
Thanks alot, in the event of an engine swap this information is priceless. I will check out the nutter bypass - having not read it, would that mean ditching my HEI? I dont have any of the stock intake stuff from the 79 but do have the dist.
If you already have an HEI, you have already killed the computer controls. Your stock Carter BBD can be set up to run sweet if you just put the air bypass pins for the stepper motor in the center of their travel where the computer would normally run them. The pins move in steps and can sometimes be rocked from the top with needle nose or a sharp mini screwdriver to get them right or you can remove the stepper motor to do it or you can put power to the pins of the stepper to move it if it hasn't seized.

A carb kit while you are at it also helps make them just purr.

I have my 86 intake and carb on a 93 4.0 HO engine now and they run sweet giving a nice 21 mpg mixed driving.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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post #23 of 28 Old 07-02-2010, 02:47 PM Thread Starter
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Quote:
Originally Posted by Mike Romain View Post
If you already have an HEI, you have already killed the computer controls. Your stock Carter BBD can be set up to run sweet if you just put the air bypass pins for the stepper motor in the center of their travel where the computer would normally run them. The pins move in steps and can sometimes be rocked from the top with needle nose or a sharp mini screwdriver to get them right or you can remove the stepper motor to do it or you can put power to the pins of the stepper to move it if it hasn't seized.

A carb kit while you are at it also helps make them just purr.

I have my 86 intake and carb on a 93 4.0 HO engine now and they run sweet giving a nice 21 mpg mixed driving.
That sounds awesome, i`ll read through the conversion thread and check out the pin stuff too - all after the knock is fixed or engine swapped!

My underhood is such a nightmare making the engine swap look really difficult, I guess if I ditch the emissions equipment and electrical would be a good time to do it.

Thanks for the help.
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post #24 of 28 Old 07-02-2010, 03:18 PM
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featured, I swapped to the wet , two barrel intake and exhaust from the '86 and went with a Rochester. Here it is about half way thru the install. I'm just more familiar with Rochester / Chevy stuff.

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post #25 of 28 Old 07-02-2010, 03:32 PM Thread Starter
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featured, I swapped to the wet , two barrel intake and exhaust from the '86 and went with a Rochester. Here it is about half way thru the install. I'm just more familiar with Rochester / Chevy stuff.


Nice and clean, how do you like it?
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post #26 of 28 Old 07-04-2010, 10:54 AM Thread Starter
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update

After not being able to find the knock I decided to pull the motor, didn't take long at all.

I found a ton of broken and disconnected vacuum lines, so i`m definitely doing the nutter bypass when I install my replacement engine. The mess of vacuum lines is very intimidating when they are all removed - I would have left them in place but many of them removed themselves long ago.
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post #27 of 28 Old 05-21-2017, 12:31 PM
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So does the trans and t-case behind a 258 handle the power of a V8? Bellhousing is the same bolt pattern I6 to v8? I know the 6 is a good torque, 4 wheeling engine but I have a good 360 to swap in place of a tired 258.

Also, speaking AMC -does the (later 70's) 4 speed swap in place of the more common 3 speed - using the same transfer case?

Another approach: does the Chevy small block / 420 or 465 trans /205 case / swap in without too many problems? (knowing that probably new drivelines and mounts have to be applied. thanks!
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post #28 of 28 Old 05-21-2017, 05:36 PM
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Quote:
Originally Posted by featured View Post
Anyways, I believe the two engines are identical but have seen some bizarre part number cut offs around 1980 - maybe this is just for the passenger car engines?
There were tons of small changes to the engine in 1980. Mostly to lighten, modernize, etc. Thats why most part numbers end/start at 1980.

Being that Jeep engines are so commonly swapped, its very common to run into "why doesnt my part fit" issue, only to discover you have a post 1980 with a pre 1980 engine, or vice versa.

The block and head castings were lighter. Different exhaust/intake manifold. (thus different exhaust system). Different carb and cleaner. Different belt system, vac system, valve cover. Different water pump, crank, etc. Different ignition system, computer controls.

So while yes, you can easily swap in that earlier long block, just keep in mind which accessories you are also swapping over. Not all of them will easily cross over.
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