Oversize/undersized main bearing question...
02-01-2016, 10:16 PM
#1
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Oversize/undersized main bearing question... I'm assembling a 408 iron block with a Lunati 4" crank & with King XP standard size main bearings my clearance is .0016 on the mains. Way too tight. Do I have to order an oversize bearing or undersize?
Backround on block: standard size bearings were originally in the block when I disassembled. Block was align bored/honed.
Also checking clearance with a bore gage & double checking with plastigage. Thanks for any help with this!
Backround on block: standard size bearings were originally in the block when I disassembled. Block was align bored/honed.
Also checking clearance with a bore gage & double checking with plastigage. Thanks for any help with this!
02-01-2016, 10:31 PM
#2
You are going to want an "X" bearing. There will usually be the regular part number followed by an X. These will give you an extra .001" clearance. You do not want a "1 under" bearing. These will have the regular part number followed by a -1. These will give you .001" less clearance.
02-02-2016, 09:26 AM
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You are going to want an "X" bearing. There will usually be the regular part number followed by an X. These will give you an extra .001" clearance. You do not want a "1 under" bearing. These will have the regular part number followed by a -1. These will give you .001" less clearance.
Oh & what do u think of the Profom rod bolt stretch guage? My gut tells me to just buy the ARP guage but are there any more affordable ones that don't suck? Lol!
Dude, thanks for your help, I really appreciate it!
02-02-2016, 12:18 PM
#5
Just want to be %100 sure. This is what I need for .001 (MORE) oil clearance, right?
Oh & what do u think of the Profom rod bolt stretch guage? My gut tells me to just buy the ARP guage but are there any more affordable ones that don't suck? Lol!
Dude, thanks for your help, I really appreciate it!
Oh & what do u think of the Profom rod bolt stretch guage? My gut tells me to just buy the ARP guage but are there any more affordable ones that don't suck? Lol!
Dude, thanks for your help, I really appreciate it!
I honestly don't remember the brand of the stretch gauge I've used, but I think it was a Proform gauge by the looks of it. It seemed to work just fine. If I remember correctly, the stretch I measured was in the range ARP recommended for the torque I applied, so I guess it was accurate.
02-03-2016, 07:39 AM
#6
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Yeah, that looks like the correct bearing.
I honestly don't remember the brand of the stretch gauge I've used, but I think it was a Proform gauge by the looks of it. It seemed to work just fine. If I remember correctly, the stretch I measured was in the range ARP recommended for the torque I applied, so I guess it was accurate.
I honestly don't remember the brand of the stretch gauge I've used, but I think it was a Proform gauge by the looks of it. It seemed to work just fine. If I remember correctly, the stretch I measured was in the range ARP recommended for the torque I applied, so I guess it was accurate.
When I check the thrust wall clearance, can I do u it with only the #3 main cap touque down or do I have to do it with all 5 caps tourque down?
Again thanks for all your help on this!
02-03-2016, 01:29 PM
#7
Hey man, sorry I have 1 more quick question. Figured I post it in here instead of starting a new thread.
When I check the thrust wall clearance, can I do u it with only the #3 main cap touque down or do I have to do it with all 5 caps tourque down?
Again thanks for all your help on this!
When I check the thrust wall clearance, can I do u it with only the #3 main cap touque down or do I have to do it with all 5 caps tourque down?
Again thanks for all your help on this!
Be sure to "set" the thrust before you check. By this I mean set the crank in and set your caps on and seated in their registers. Snug the bolts on the #3 cap but not too tight. I use a 3" long piece of aluminum round bar set up against the snout of the crank and give it a good whack with a hammer. Then I do the same against the rear flange. This "sets" the thrust in the block. You want to do this when you assemble the engine as well.
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02-03-2016, 02:04 PM
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At least #1 and #5 as well.
Be sure to "set" the thrust before you check. By this I mean set the crank in and set your caps on and seated in their registers. Snug the bolts on the #3 cap but not too tight. I use a 3" long piece of aluminum round bar set up against the snout of the crank and give it a good whack with a hammer. Then I do the same against the rear flange. This "sets" the thrust in the block. You want to do this when you assemble the engine as well.
Be sure to "set" the thrust before you check. By this I mean set the crank in and set your caps on and seated in their registers. Snug the bolts on the #3 cap but not too tight. I use a 3" long piece of aluminum round bar set up against the snout of the crank and give it a good whack with a hammer. Then I do the same against the rear flange. This "sets" the thrust in the block. You want to do this when you assemble the engine as well.
02-05-2016, 11:14 PM
#12
Staging Lane
Can this be fixed by using 1/2 +.002" and 1/2 +.001" shells. The Ford factory manuals for the “Indy” 255, “Le Mans” 427, and “Trans Am” Boss 302 recommend this procedure.
Last edited by panic; 02-06-2016 at 09:46 AM.
02-07-2016, 08:55 AM
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I'm driving myself nuts trying to figure out if I should run the mains with the clearance I got with the "X" bearings. What do u think? I got pretty much the same range of clearance on the mains as I have on the rods. Shouldn't I be up about .0025- .0030 on the mains? If so how do I achieve that? Another set of bearings? Maybe polish the crank (I would like to avoid this if possible as it's a new stroker crank)??? Also this is being built for the street not the the track. What do u think?
02-07-2016, 09:29 AM
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Hey man I need to bother u again! Lol!
I'm driving myself nuts trying to figure out if I should run the mains with the clearance I got with the "X" bearings. What do u think? I got pretty much the same range of clearance on the mains as I have on the rods. Shouldn't I be up about .0025- .0030 on the mains? If so how do I achieve that? Another set of bearings? Maybe polish the crank (I would like to avoid this if possible as it's a new stroker crank)??? Also this is being built for the street not the the track. What do u think?
I'm driving myself nuts trying to figure out if I should run the mains with the clearance I got with the "X" bearings. What do u think? I got pretty much the same range of clearance on the mains as I have on the rods. Shouldn't I be up about .0025- .0030 on the mains? If so how do I achieve that? Another set of bearings? Maybe polish the crank (I would like to avoid this if possible as it's a new stroker crank)??? Also this is being built for the street not the the track. What do u think?
I'm with in GM specs on both rods & mains but that's for a stock crank & stock rods.
I was reading and some guys choose a different brand of bearing & some polish/ grind the crank. Hmm, what to do, what to do? Lol!
02-07-2016, 09:41 AM
#16
Hey man I need to bother u again! Lol!
I'm driving myself nuts trying to figure out if I should run the mains with the clearance I got with the "X" bearings. What do u think? I got pretty much the same range of clearance on the mains as I have on the rods. Shouldn't I be up about .0025- .0030 on the mains? If so how do I achieve that? Another set of bearings? Maybe polish the crank (I would like to avoid this if possible as it's a new stroker crank)??? Also this is being built for the street not the the track. What do u think?
I'm driving myself nuts trying to figure out if I should run the mains with the clearance I got with the "X" bearings. What do u think? I got pretty much the same range of clearance on the mains as I have on the rods. Shouldn't I be up about .0025- .0030 on the mains? If so how do I achieve that? Another set of bearings? Maybe polish the crank (I would like to avoid this if possible as it's a new stroker crank)??? Also this is being built for the street not the the track. What do u think?
You could try a different brand. I usually use an ACL or Federal Mogul brand.
02-07-2016, 09:45 AM
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Yeah, if you were at .0016" with standard bearings, I'm surprised you only got .0023" with the X bearings. That clearance will probably be fine for a NA street setup, but I like to have at least .0025" on an iron block.
You could try a different brand. I usually use an ACL or Federal Mogul brand.
You could try a different brand. I usually use an ACL or Federal Mogul brand.