360 main bearings question

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moparracer54

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I need to order main bearings for my 71 360. As I recall there was something different between the early 1970s 360s and newer ones but what is it?
 
Yep, they made the thrust surface bigger as a running change in 74.
 
i believe you can use the newer bearing on the older block but not the other way..
 
70aarcuda said:
i believe you can use the newer bearing on the older block but not the other way..
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..............its been awhile since I've worked on 1, but I think u can use the older bearing on the newer block as the recess in the old block is too small of a diameter for the newer bearing,, but I think the new bearing has a bigger thrust surface, but I could be wrong, memory isn't what it used to be........kim.......
 
oldkimmer said:
..............its been awhile since I've worked on 1, but I think u can use the older bearing on the newer block as the recess in the old block is too small of a diameter for the newer bearing,, but I think the new bearing has a bigger thrust surface, but I could be wrong, memory isn't what it used to be........kim.......
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LOL......I have a 72 block that I will putting together in about two weeks...I will try the newer bearing on the thrust and see..

After thinking for a minute..I think you are right..
 
oldkimmer said:
..............its been awhile since I've worked on 1, but I think u can use the older bearing on the newer block as the recess in the old block is too small of a diameter for the newer bearing,, but I think the new bearing has a bigger thrust surface, but I could be wrong, memory isn't what it used to be........kim.......
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I've used the later bearing #1266 full groove 1974-2002 in my 72 blocks, no fitment problems here. I believe the change had more to do with the width of the thrust surface of the crank ie wider on the later motors.
 
70aarcuda said:
i believe you can use the newer bearing on the older block but not the other way..
Click to expand...


No, the new change added more material to the thrust face of the bearings which required them to machine the depth of the cut deeper for the "new" ones after 74.

They did bring the machine changes early, and on some of the "old" blocks the new thrust bearing will fit, but the old one will fit on everything (smaller thrust face).

If your block is machined enough to take the newer bearing, that is the better way to go....
 
I'll second Krazy there but I thought the years were a little different. The old bearing (70-71 castings IIRC) works on everything, newer style works on those with the larger thrust cut. I think they made the change after '71 so some 72 model year year blocks got it.
 
moper said:
I'll second Krazy there but I thought the years were a little different. The old bearing (70-71 castings IIRC) works on everything, newer style works on those with the larger thrust cut. I think they made the change after '71 so some 72 model year year blocks got it.
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Yes. The old bearing will fit everything for sure.

The newer bearing requires a deeper spot face and some of the older blocks had it.

You are better running the newer bearing if it will fit as it is improved with more surface area to distribute the load.
 
Since I have a "couple" of 360 blocks .....

Looked at a 72 block and 84 block.....both had the MB 2623P bearing on the thrust ....that bearing comes with the MS 1266P set.....



the 71-73 thrust bearing is mb 2591p
 
moper said:
I'll second Krazy there but I thought the years were a little different. The old bearing (70-71 castings IIRC) works on everything, newer style works on those with the larger thrust cut. I think they made the change after '71 so some 72 model year year blocks got it.
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When I was rebuilding a 74 360, Mancini asked me which bearings I needed as their books listed the bearing change in mid year 74....

Of course I had to have the "questionable" year.... :banghead:


But I have seen older blocks than that with the larger scallop for the thrust bearing that can accept the larger bearing.
 
Well...the 72 block had a casting date of 6/29/72.....and had the 73+ bearing in it...
 
Big blocks are the same way. Early/narrow thrust surface, late/wide.
 
I have a 360 block that was built in 1970 and I use #1266 full grove bearings. I spin mine to 7,700 rpm through the traps and It runs in the low 10's like 10.10 at 131mph. Never had a problem. Full grove is the way to go keeps oil on the rod bearings all the time. Be sure to run a high volume oil pump with a big oil pan 7+ quart and you will be fine.
 

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dart19666 said:
I have a 360 block that was built in 1970 and I use #1266 full grove bearings. I spin mine to 7,700 rpm through the traps and It runs in the low 10's like 10.10 at 131mph. Never had a problem. Full grove is the way to go keeps oil on the rod bearings all the time. Be sure to run a high volume oil pump with a big oil pan 7+ quart and you will be fine.
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We need to know more about this low 10 second 7700 RPM machine. :burnout:

X 2 on the full groove main bearings.
 
My parts house had a spec for the #3 main bearing flange of either 3.910" or 3.685". I been sitting on this scrap of paper for several years & this is an opportunity to toss it out there as it might be beneficial to this issue
 
And I always thought there was a difference in the location of the locating "tang" on the #5 bearing on the 71-72 blocks.
 
I just converted to full groove mains (bought a new set of identical half grooved bearings & used half of em) when I refreshed/modded my circle track 360 & I had to cut a new tang groove in the block (#5 iirc) for the new grooved bearing half as the non grooved bearing half, it's tang was located differently fore/aft. EDIT dont know offhand the block year. MORE EDIT with more thought, the groove i cut was in the cap as that was where the ungrooved bearing half was that I replaced with a grooved one
 
skrews said:
We need to know more about this low 10 second 7700 RPM machine. :burnout:

X 2 on the full groove main bearings.
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I did a full report when I freshened it up. I am still new here and have no idea how to post a link to a different link.
 
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