Crate engine vs?

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sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Crate engine vs?

Post by sierrablue »

candymancan wrote: Thu Mar 16, 2023 6:59 pm
tgreese wrote: Tue Feb 28, 2023 5:37 am 160 on the other cylinders is good, not worn out. You understand that when the engine is worn, all the cylinders lose compression, not just one.

You need the actual reading for each cylinder, wet and dry. The difference between each cylinder (10 psi? 20 psi? How consistent?) matters. The change in compression when you add oil to the cylinders (a "wet" compression test) will separate bad valves from bad rings. Your mechanic should give you this info, or do it for you if he hasn't, or you can do it yourself easily.

Yeah, you need better diagnosis. From what little you've been able to tell us, you could probably remove that cylinder head and fix the valve. You understand that one bad cylinder is something you need to fix, but not necessarily worn out? What's your oil pressure, on the highway and at full-temperature hot idle?

Sorry to jump on this ship.. but my 360 said 150 on 1-7 and like 130 on 8. Oil didnt change it one bit.

So does this mean i have bad valves.. or a cam on cylinder 8 ?
You're pretty close to the 10% margin most people say so I just wouldn't worry about it, especially with all the other stuff you've got going. All of mine are in the 150s, except for the back two on the passenger's side, which are like 115-120. Still runs fine, and I know it's never been rebuilt other than just the gaskets I did--no reason to screw with it right now.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

customfab4x4
Posts: 4
Joined: Tue Mar 21, 2023 1:56 am

Re: Crate engine vs?

Post by customfab4x4 »

I have been in an internal debate with myself on my 1980 Cherokee Laredo which is all original but motor is barely hanging on.

Personally I see these AMC motors has low mileage throw away motors compared to GM and Ford motors. They are not known for reliability and almost all of them will eventually leak oil. Can they be rebuilt and improved upon for higher mileage? Absolutely YES. Any good AMC builder knows what improvements are critical during a rebuilt such as expanding the oil passages and ensuring even oil flows across all cylinders.

But the downside of rebuilding is the expense. For me, I am looking at over $5K in a complete rebuild for a 400HP 360 AMC with EFI port injection. And everything I seek.

However, I can land a 2014 - 2017 LS 5.3L L83 motor + 8L90 tranny (has known issues itself) + NP261 for $5000. That is from a donor car with less than 50k.

Entire reason why LS swaps are so popular. Downside....is that if you do not have the technical skills.....paying for a LS swap is $15-20K typically.

So if u want to keep original and don't care about much of a performance boost with a carb motor....you can buy a rebuild motor for under $5K. And then he done with it.
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tgreese
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Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: Crate engine vs?

Post by tgreese »

customfab4x4 wrote: Wed Mar 22, 2023 6:50 am... Personally I see these AMC motors has low mileage throw away motors compared to GM and Ford motors. They are not known for reliability and almost all of them will eventually leak oil. ...
IMO this is wrong-headed. You can easily find Wagoneer owners on these boards with original engines that have gone 200K or 300K miles. (Also my opinion - maintenance makes much more difference than brand). Pretty sure the AMC engines' longevity was easily on par with other commodity V8 engines of the day, ie Ford, GM or Chrysler. The sixes were notably better than most.

Comparing the average longevity of these 50-year-old-designs with today's engines - or even the past two decades' designs - is apples to oranges.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Crate engine vs?

Post by sierrablue »

I definitely know where you're coming from for the AMC stuff. It does come down more to how well people treated it on the V8s, however, the AMC isn't a very good design, just because it doesn't flow very well.

tgreese, the AMC 6s are decent, and GM's sucked, but the Dodge 6s are pretty solid, and the Ford 6s...well my dad had a friend who was actively TRYING to break it (his dad said he'd get a 460 if the 6 ever blew up), drove it the 6 hours to Chicago and back (3 each way) on one quart of oil and couldn't break it. The AMCs aren't super special for durability.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Crate engine vs?

Post by sierrablue »

customfab4x4 wrote: Wed Mar 22, 2023 6:50 am I have been in an internal debate with myself on my 1980 Cherokee Laredo which is all original but motor is barely hanging on.

Personally I see these AMC motors has low mileage throw away motors compared to GM and Ford motors. They are not known for reliability and almost all of them will eventually leak oil. Can they be rebuilt and improved upon for higher mileage? Absolutely YES. Any good AMC builder knows what improvements are critical during a rebuilt such as expanding the oil passages and ensuring even oil flows across all cylinders.

But the downside of rebuilding is the expense. For me, I am looking at over $5K in a complete rebuild for a 400HP 360 AMC with EFI port injection. And everything I seek.

However, I can land a 2014 - 2017 LS 5.3L L83 motor + 8L90 tranny (has known issues itself) + NP261 for $5000. That is from a donor car with less than 50k.

Entire reason why LS swaps are so popular. Downside....is that if you do not have the technical skills.....paying for a LS swap is $15-20K typically.

So if u want to keep original and don't care about much of a performance boost with a carb motor....you can buy a rebuild motor for under $5K. And then he done with it.
I'd go ahead with the LS. I'm not a huge fan of the LS, but if you do some work yourself, you can get the LS you want AND an o/d transmission in it for under $10k. And it'll last awhile. And you can find parts.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.
User avatar

tgreese
Posts: 7118
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: Crate engine vs?

Post by tgreese »

sierrablue wrote: Thu Mar 23, 2023 4:33 pm ... tgreese, the AMC 6s are decent, and GM's sucked, but the Dodge 6s are pretty solid, and the Ford 6s...well my dad had a friend who was actively TRYING to break it (his dad said he'd get a 460 if the 6 ever blew up), drove it the 6 hours to Chicago and back (3 each way) on one quart of oil and couldn't break it. The AMCs aren't super special for durability.
Huh. Do you know what hubris is? Also, suggest you look up anecdotal evidence. This is so far off-topic from the original post that I'm not going to elaborate.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Crate engine vs?

Post by sierrablue »

I was responding to your comment that AMC I-6s were somehow heavenly engines compared to other American I-6s. That's all it was. The only reason that old stuff lasts longer is that when mechanical stuff goes bad, it goes bad slowly, and doesn't all out fail. New stuff has electronics, which all-out fail when they go bad, thus you have no chance of making them keep working right or well enough without it. Additionally they're more efficient to begin with so you notice bigger losses when it goes bad.

And what does hubris have to do with anything? None of that was MY stuff, and I'm just repeating what I've read/heard/seen about the stuff.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

Srdayflyer
Posts: 398
Joined: Mon Mar 18, 2019 2:08 pm

Re: Crate engine vs?

Post by Srdayflyer »

anyone in california having state emmissions issues with a cherokee, or J10/20 id be interested it taking it off your hands
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