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Later large thrust main bearings #3066855
08/10/22 04:08 PM
08/10/22 04:08 PM
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Seattle, WA
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375inStroke Offline OP
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Should one always use the larger thrust main bearings found on later big blocks? I'm building a motor for a manual transmission car, and I'm thinking the larger thrust area is a good thing if it fits your block.

Last edited by 375inStroke; 08/10/22 07:01 PM.
Re: Later large thrust main bearings [Re: 375inStroke] #3066868
08/10/22 05:22 PM
08/10/22 05:22 PM
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Loudoun County, VA
Brad_Haak Online content
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Brad_Haak  Online Content
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If you're working with a later production block that can accept the larger flange diameter, makes sense to me.

Re: Later large thrust main bearings [Re: Brad_Haak] #3066927
08/10/22 08:50 PM
08/10/22 08:50 PM
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Stuttgart, Arkansas
rickseeman Online content
top fuel
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If you can't find a large flange thrust bearing that gives the clearance you want don't worry. People ran the small thrust in Top Fuel for years.


2011 Drag Pak Challenger
Re: Later large thrust main bearings [Re: 375inStroke] #3066944
08/10/22 09:53 PM
08/10/22 09:53 PM
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Bend,OR USA
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Cab_Burge Offline
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I think you have to run the later center main on all the later blocks due to the way Mopar machine that center main in the block and in the cap, I don't think you can run an early center main bearing in a 1973/1974 440 and later block, maybe so confused


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Later large thrust main bearings [Re: rickseeman] #3066990
08/11/22 07:03 AM
08/11/22 07:03 AM
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375inStroke Offline OP
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Originally Posted by rickseeman
If you can't find a large flange thrust bearing that gives the clearance you want don't worry. People ran the small thrust in Top Fuel for years.


I'm more concerned about longevity with the clutch pushing on the crank on a street car.

Re: Later large thrust main bearings [Re: 375inStroke] #3067006
08/11/22 08:39 AM
08/11/22 08:39 AM
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Michigan
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Transman Offline
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Originally Posted by 375inStroke
Originally Posted by rickseeman
If you can't find a large flange thrust bearing that gives the clearance you want don't worry. People ran the small thrust in Top Fuel for years.


I'm more concerned about longevity with the clutch pushing on the crank on a street car.


How about all the manual trans equipped engines with the early thrust - they never seemed to have any issues.
And all the race cars with the small thrust, no issues there either.

If you have the large thrust block, go for it.

Last edited by Transman; 08/11/22 08:40 AM.
Re: Later large thrust main bearings [Re: Cab_Burge] #3067030
08/11/22 11:00 AM
08/11/22 11:00 AM
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Originally Posted by Cab_Burge
I think you have to run the later center main on all the later blocks due to the way Mopar machine that center main in the block and in the cap, I don't think you can run an early center main bearing in a 1973/1974 440 and later block, maybe so confused


Cab, the small thrust main will fit in a large thrust main crank line .


running up my post count some more .
Re: Later large thrust main bearings [Re: 375inStroke] #3067032
08/11/22 11:05 AM
08/11/22 11:05 AM
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Originally Posted by 375inStroke
Originally Posted by rickseeman
If you can't find a large flange thrust bearing that gives the clearance you want don't worry. People ran the small thrust in Top Fuel for years.


I'm more concerned about longevity with the clutch pushing on the crank on a street car.


Will you be idling for hours with your foot on the clutch ?

If you can find the large thrust mains and they fit the block then use them . I've seen people say to file a very small angle (chamfer) on the rear side of the center main, in a 4 speed car, from the groove in the middle of the main bearing so it sends some pressurized oil to the rear thrust surface. I've done it to a couple engine I have in the works, and to a friends engine and didn't see any oil pressure issue because of it .

Last edited by JohnRR; 08/11/22 11:29 AM.

running up my post count some more .
Re: Later large thrust main bearings [Re: JohnRR] #3067033
08/11/22 11:14 AM
08/11/22 11:14 AM
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Transman Offline
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Originally Posted by JohnRR
Originally Posted by 375inStroke
Originally Posted by rickseeman
If you can't find a large flange thrust bearing that gives the clearance you want don't worry. People ran the small thrust in Top Fuel for years.


I'm more concerned about longevity with the clutch pushing on the crank on a street car.


Will you be idling for hours with your foot on the clutch ?

If you can find the large thrust mains and they fit the block then use them . I've seen people say to file a very small angle on the rear side of the center main, in a 4 speed car, from the groove in the middle of the main bearing so it sends some pressurized oil to the rear thrust surface. I've done it to a couple engine I have in the works, and to a friends engine and didn't see any oil pressure issue because of it .


Same principle from back in the day when the number 1 main bearing had a chamfer on the parting line to spray oil on the timing chain.

Re: Later large thrust main bearings [Re: Transman] #3067035
08/11/22 11:28 AM
08/11/22 11:28 AM
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Originally Posted by Transman
Originally Posted by JohnRR
Originally Posted by 375inStroke
Originally Posted by rickseeman
If you can't find a large flange thrust bearing that gives the clearance you want don't worry. People ran the small thrust in Top Fuel for years.


I'm more concerned about longevity with the clutch pushing on the crank on a street car.


Will you be idling for hours with your foot on the clutch ?

If you can find the large thrust mains and they fit the block then use them . I've seen people say to file a very small chamfer on the rear side of the center main, in a 4 speed car, from the groove in the middle of the main bearing so it sends some pressurized oil to the rear thrust surface. I've done it to a couple engine I have in the works, and to a friends engine and didn't see any oil pressure issue because of it .


Same principle from back in the day when the number 1 main bearing had a chamfer on the parting line to spray oil on the timing chain.


I did not know that , thanks

and thanks, chamfer was the word I was looking for


running up my post count some more .






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