Line Bore Size?
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
Align Bore Size?
Does anyone know what the Align Bore size for the mains is supposed to be standard on a SBC? I need the size and the tolerances. I dont have a book with it in it and believe it or not I cant find anything on google.
Last edited by smooth1990; Nov 8, 2014 at 12:28 PM.
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
2.6410 is the target size..... tollerance would be 2.6405 to 2.6415
However I am going to warn you here about that "tollerance" on the blocks main line.
With the way companies (espc Eagle) grind cranks on the big end of 2.448..... alot end up at nearly 2.449..... and you only have one option on your bearings for EXTRA clearance.... so if you're crank is on the big side and your needing more that .002 brg clearance.... you MUST have the blocks main line sized on the big side and use an X brg just to get enough clearance.
It sucks but thats building racing engines today.
Will
Will
However I am going to warn you here about that "tollerance" on the blocks main line.
With the way companies (espc Eagle) grind cranks on the big end of 2.448..... alot end up at nearly 2.449..... and you only have one option on your bearings for EXTRA clearance.... so if you're crank is on the big side and your needing more that .002 brg clearance.... you MUST have the blocks main line sized on the big side and use an X brg just to get enough clearance.
It sucks but thats building racing engines today.
Will
Will
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
2.6410 is the target size..... tollerance would be 2.6405 to 2.6415
However I am going to warn you here about that "tollerance" on the blocks main line.
With the way companies (espc Eagle) grind cranks on the big end of 2.448..... alot end up at nearly 2.449..... and you only have one option on your bearings for EXTRA clearance.... so if you're crank is on the big side and your needing more that .002 brg clearance.... you MUST have the blocks main line sized on the big side and use an X brg just to get enough clearance.
It sucks but thats building racing engines today.
Will
Will
However I am going to warn you here about that "tollerance" on the blocks main line.
With the way companies (espc Eagle) grind cranks on the big end of 2.448..... alot end up at nearly 2.449..... and you only have one option on your bearings for EXTRA clearance.... so if you're crank is on the big side and your needing more that .002 brg clearance.... you MUST have the blocks main line sized on the big side and use an X brg just to get enough clearance.
It sucks but thats building racing engines today.
Will
Will
My crank was ground on the mains. turns out there was some issues from the previous machine shop, hence the bearing issues. So my mains are now .020 under and rods are .010 under. ( was ground last time to .010)
I mic'd the crank out last night just to verify the machine shops work and the rod journals are 2.0895. They are all round and on size. no tapers either. The mains are 2. 429. No tapers. Not out of round anywhere either.
I want to check and double check everything this time around. It seems the align bore is a .0005 out of the tolerance already.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,465
Likes: 12
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
I would want .003 brg clearance on the mains.... but from what your measurements tell me its going to be a struggle just to get .0025 and anything more may be impossible because of brg availability in .020 undersize.
In this case if I could get .0025 or better by opening up the blocks main line to the high side of the tollerance, I would call it good.
Will
In this case if I could get .0025 or better by opening up the blocks main line to the high side of the tollerance, I would call it good.
Will
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