258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

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tgreese
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by tgreese »

Also, the '71 engine may have higher compression because it has different pistons. There was a piston change mid-77. The location of the water temperature sending unit will tell.

Regarding the compression test, usually you do a wet and dry test, compare the change and the balance between cylinders. May not be a great test for an engine that's sat for years, but that's the usual test. Good balance indicates healthy, since worn rings tend to make differences between the cylinders.
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.

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backroader
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

Thanks for the tips...

The compression tests on the two engines that have been sitting were done with the cylinders oiled in advance, so they could be considered "wet". The numbers for all three were within 10# or less between the six on each, but the numbers for the Waggie engine were significantly higher than both of the other two.

I have a drawing showing the adapter bushing that was available from AMC at one point in time to adapt the crank to fit a Torqueflite.. AMC part # 321 6130. Sounds like it would have to be made in a machine shop now.

Also have a photo showing the recess in the older style crank. I tried to upload both images, but I must be doing something wrong..

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backroader
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

Link to sketch showing the adapter. On the forum, however, they are calling the crank flange a "Flat Flange" crank, so this is just one example of the conflicting information that is available.

https://theamcforum.com/forum/727-adapt ... 60185.html
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tgreese
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by tgreese »

As I understand that drawing and thread, you need to machine out the end of the crank to accept that adapter.

Later in that thread, they describe an adapter for the 1971 engines that sits proud of the crank end and spaces the bell housing further away from the engine. I can see how that would work.

Something I thought of later - the Borg-Warner transmissions have a removable bell. It's likely that AMC used a new bell housing that matches the AMC pattern but kept the crankshaft design for their 1971 cars. This would explain why your '71 engine has the starter on the passenger side, and would agree with the listings from the parts book.
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.

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backroader
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Joined: Fri Oct 26, 2018 7:31 am

Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

Something I thought of later - the Borg-Warner transmissions have a removable bell. It's likely that AMC used a new bell housing that matches the AMC pattern but kept the crankshaft design for their 1971 cars. This would explain why your '71 engine has the starter on the passenger side, and would agree with the listings from the parts book.
According to information posted on the internet by Frank Swygert, editor and publisher of the AMC/AIM magazine, and guru of all things AMC, the block casting number of the engine in the 71 Wagoneer indicates the engine was built somewhere between 1975 and 1979. Block casting number is 3227445, incidentally, the same block casting number as the engine in the 1977 J10 chassis I have.

https://www.jeepforum.com/threads/ident ... e.1383352/

I did know how to interpret the build date code at one point, but can't remember how it all goes now. I know it's out there in the AMC info somewhere on the internet.
Last edited by backroader on Tue Apr 11, 2023 6:10 pm, edited 1 time in total.

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backroader
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

Here is the info on how to decipher the date code:

"The Engine Day Build Code consists of six characters:

1. Year built code 2 & 3. Number of the month 4. Engine size/type code 5 & 6. Day built

Thus, "409C21" indicates 1962, September, 195.6 OHV (cast iron), 21st day. The only way to determine the year is 1962 instead of 1971, 1984, or 1992 is to know that the 195.6 OHV engine was discontinued after 1965, and what a 195.6 looks like (very different than the 199/232/258). Most codes do not overlap very much. For those that do (such as 3 -- 1961, 1970, 1979, 1983, 1993) casting numbers may have to be consulted if the engine date is important, such as for a restoration.

Day Built "Year Codes"
1=1959 2-1960 3=1961 4=1962 5=1963
6=1964 7=1965 8=1966 9=1967 1=1968
2=1969 3=1970 4=1971 5=1972 6=1973
7=1974 8=1975 9=1976 1=1977 2=1978
3=1979
Beginning in 1980 the last digit of the year is used (1980=0, 1981= 1, etc.)"

So, most likely, the block, at least, in the 71 Waggie was built in 1978. Of course, that doesn't necessarily mean all the engine components, such as the crank, were also built in 1978.
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tgreese
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by tgreese »

Mmm. If the engine was replaced in the '71, the block could come from a later engine and the crank from a '71. That's how engines are "remanufactured." The cores come in and they are broken down into their component parts. Then the factory "remanufactures" these parts to assemble an engine, picking compatible parts from stock.

Any TSM from this era will describe the build date code. The first character is the year, with 7 as 1974. The numbers go forward, skipping 0 it seems. So '71 is 4, '72 5 etc. At some point they reset so that 1982 is 2. 2nd and 3rd character are the month, ie 04 is April. Next is the engine type, E, A or C for 232 1V, 258 1V or 258 2V resp. Note the 2V engine was introduced in 1977 for the FSJs, so C not present prior to that. Last two characters are the day of the month.

NB the model year starts in the late summer, so a '77 engine could have a date code of 1976 (9) or 1977 (1).
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.

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backroader
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

tgreese wrote: Tue Apr 11, 2023 10:16 am Maybe this -

https://theamcforum.com/forum/bw-vs-tor ... 90775.html
Some really good information, here, thanks...

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backroader
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

I think I'll probably look into availability and cost of the adapter first, and take it from there. I've had good results with BJ's Offroad in the past, so I'll probably start with them.

Thanks again..
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tgreese
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by tgreese »

NP. Glad if it helps.
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.

candymancan
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by candymancan »

Wow nice thread.. sorry to hijack it but since were talking 258 and transmissions.

Im looking at a 78 J10 258 quadratrack auto. I assume its a th400 right ? Which 258s would bolt in ? This engine threw a rod through the block.. no idea how the owner managed that. But yea. Jeep is 700$ in otherwise good condition. But needs an engine hense why its 700$ despite minimal rust. I doubt many buyers want a bad engine J10 shirt bed. With a 6 cylinder. Its probly why it hasnt been snatched up. Most probly want a 360.. i admit i dont want a 6 cylinder either.. theyre what like 100hp ? How does that even move a 4000 lbs truck ?

Also if it has a th400 ? Wouldnt a 360 swap right in ? Or is a 360 th400 diff from a 258 ?

Anyway. So which years would i need to look for and stay away from ?
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)
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tgreese
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by tgreese »

I answered most of this in your other thread.

There are quite a few differences between the six and V8 trucks. The six is longer than the V8, and everything moves backward for the six. This is why the low range won't work - no room to the gas tank. V8 mounts are different. Core support and radiator are different. Battery position is different. Lots of old threads about this.

I would go modern SBC and drivetrain rather than changing all that's needed for a 360.

Also your transmission is a TH400 without the ring adapter. 1974ish AMC switched to having TH400s built for them by GM with the right case pattern for their engines. No more adapter. That truck has the AMC case and no adapter.

Any '72 or later 232 or 258 will bolt in. This whole thread is about a single year, 1971.
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.

candymancan
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Joined: Tue Mar 22, 2016 11:32 pm

Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by candymancan »

Ah okay thanks.
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

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backroader
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

Continuing on with my research on 258 crankshaft compatibility, it sounds like most, if not all, 258 cranks were the same until they transitioned from V-belts to serpentine belts. At that time, the length of the snout of the crank was changed to accommodate a pulley for a serpentine belt. This is generally presumed to have taken place along with the other engine changes in 1981, however, not all 258 engines were equipped with serpentine belts in 1981. Like the truck I have, for one example.

They handled the differences in transmissions through the use of different flex plates, and sometimes with adapters and bushings. So as near as I can tell from the information I have been able to gather is a crank from a 1971 258 I6 should bolt up to a 1981 Torqueflite auto as long as I have the correct flexplate.

There is a lot of useful information regarding Jeep and AMC flex plates, flywheels, and various engines at this link: https://rebsamcandjeep.proboards.com/th ... flexplates

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backroader
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Re: 258 I6 Borg Warner to Torqueflite 727 crankshaft compatibility

Post by backroader »

Pulled the engine out of the Waggie yesterday, and the crank had about a 1 inch adapter with a bushing in it for the Borg Warner torque converter between the crank flange and the flex plate. The crank flange itself appears to be the same as the one used in the later 258 models, so I believe I am in luck with the swap at this point...
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