Nobody wants to help me out here so hopefuly someone will. I have a 420a that broke a rod, messed up the crank, and put a hole in the main bearing girdle. I have already gotten a crank and had it micropolished because that's all it needed. I now have the main bearing girdle as well and my question is do I need to have it line bored or will it be fine? I have did this on my Civic before and never had any problems and never had it line bored.
To Line Bore Or Not To Line Bore? That Is the Question!
azazel182
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Nobody wants to help me out here so hopefuly someone will. I have a 420a that broke a rod, messed up the crank, and put a hole in the main bearing girdle. I have already gotten a crank and had it micropolished because that's all it needed. I now have the main bearing girdle as well and my question is do I need to have it line bored or will it be fine? I have did this on my Civic before and never had any problems and never had it line bored.
azazel182 said:
line boring sets the crank and all journal centerline in the block. most likely they will take material off the top of the mains in the block then shave a little off the top of the gurlde to make up for this to get it the right size. if your not using the original gurdle then by all means do this or your going to have messed up bearing clearances causing problems. We all know oil pump + bearing clearances basically determine your oil pressure. i dont know the specs here on the 420a block but like any engine im going to guess its .002-
.004 thousandths tollerance from crank to bearing. While your at it throw some arp main studs in it. DO NOT re-use your rod bolts either. these are throw away item and are cheap insurance against anything happeneing. check rods to be re-conditioned, wrist pins for gaulling, the obvious stuff.
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I would junk that block entirely.
Grab a new one with a clean slate and go from there.
Line bore's can be tricky. And easy for a good shop to screw up.
You have new everything else... why not go pull a 420a from the yard?
Should cost you what? $100? Considering all the rest you have invested...
I would simply skip all that bullshit.
If you got away with it on a Honda its just a testament to their manufacturing specs. Their tolerances in the bottom must be less than a half thou or less variance from target. (for you to successfully get away with it)
I wouldn't expect the same level of dedication on a 420a from Mitsler.
At all.
Grab a new one with a clean slate and go from there.
Line bore's can be tricky. And easy for a good shop to screw up.
You have new everything else... why not go pull a 420a from the yard?
Should cost you what? $100? Considering all the rest you have invested...
I would simply skip all that bullshit.
If you got away with it on a Honda its just a testament to their manufacturing specs. Their tolerances in the bottom must be less than a half thou or less variance from target. (for you to successfully get away with it)
I wouldn't expect the same level of dedication on a 420a from Mitsler.
At all.
I have looked around at all the local salvage yards and nobody seems to have one. I have found a few SOHC 2.0 Neons. From what I hear the bottom end is the same. If this is true I'll just buy the shoft block or whatever they will let me do. I am not hell bent on using this block I just didn't know if I could get away with it. I'll search around a little more. Thanks for all the input!
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DSM Loki said:
You noticed that too? lol
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When you say "Girdle" do you mean the "Bedplate". Girdle on a Honda and Bedplate on 420A I believe are 2 different monsters. For those that don't have a 420A it does not have main bearing caps like other engines, it has a bedplate about 2.5-3" thick that serves as the caps or bedplate. Did you damage this piece? I would think you could lay the crank in and check all your bearing clearances, crank play, etc.. and if everything is fine, it should be ok? ...................Jim
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Asmo's dog got a DSM...DSM Loki said:
azazel182 said:
whoa whoa whoa, you cannot use that bedplate without getting it align honed. the way the blocks are cast, they have to bore the main journals after bolting a rough-bored bedplate on. because of this, each bedplate can only be used with the block it came on unless you align hone it.
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Anaerobic sealant. Loc-tite 518 or Permatex 51813azazel182 said:
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169 Posts
If you are useing a bedplate from another block then yes you absolutely must have the block line bored. If you don't then there is a very good chance that the crank tunnel will not be straight or round. Your better off finding another good block. At worst you'll only have to hone the cyl and have it line honed wich would be cheaper than having the crank tunnel bored.azazel182 said:
Good luck.
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