Main and rod bearing oil clearances b18c


jesse888

jesse888

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Been looking around the interwebs for some answers but found afew different measurements coming up.
So I thought I'd ask here incase anyone has a book or any proper documentation on what the clearances should be?
Looking for
crankshaft main journal bearing clearance
Connecting rod bearing clearance
Piston ring gap clearances if someone's got them aswell

Any other info on building a b18c(6) is welcome but mainly after the clearances.
 
theres a guy on here called shaun from anodover hes got my teg workshop manual which has every bit of info you need jesse just finding him on here...
 
It took me some time to find , I found a PDF file with all b18c5 which is the same but US spec . Will let u know . U hav to look at the number stamped on yr con rod like 24 then look at yr crankshaft mine is X so bearings are brown for me.
 
I won't have the conrods that was on the b18 crankshaft. Only my b16b ones. Plus I'll be installing forged rods, does this make any difference?
 
Yes , yr need to measure the cap clearance, and use platigauge
Got all my bearning from States $17 each
 
jesse888 said:
I won't have the conrods that was on the b18 crankshaft. Only my b16b ones. Plus I'll be installing forged rods, does this make any difference?
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Unless you have very good measuring equipment your going to have to plastigauge each one probably starting from green's.

At about £15 a shell (iirc) it gets expensive
 
Nice. Can I not measure the journals with a micrometer to check that they are within spec. Then, if they are, order the stock size acl bearings.
Or does it not work like that?
 
Here's a guide from Honda tech on how to select/ calculate sizes

http://m.honda-tech.com/showthread.php?t=715490&styleid=18

It's quite common that each bearing will be a different size (from factory) and pretty rare to need the same colour across the whole crankshaft and quite often you see two different colours per journal for example on a rod bearing one half may be green the other half may be brown to achieve the desired clearance. (that's what I've seen on the few I've pulled apart anyway)

In all honesty it's a proper ball ache!

I've seen quite a few builds where people have stuck a set of acl's in hoped for the best and been fine.
 
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I'll give that a read and see what happens, I want to do it properly.
 
So, my new block I had last year , from honda engine went due to a valve spring . My crank is good still but a few bearing had some marks so I orderd all new just in case £1700 down the drain and a few big end had marks on them . Honda prices £££
 
jesse888 said:
Nice. Can I not measure the journals with a micrometer to check that they are within spec. Then, if they are, order the stock size acl bearings.
Or does it not work like that?
Click to expand...

What about measuring the rods? When I did mine, I had a spare set of Red bearings and plastigauged them. Then worked out what colour bearings I needed from the workshop manual.

Murray
 
So reading that I need to measure each journal for the conrods, I don't mind buying quality tools to be able to do it. Just need the knowledge.
I'll check my work with plasti gauge aswell to be sure I've got it right, could take some time lol
 
Murray said:
What about measuring the rods? When I did mine, I had a spare set of Red bearings and plastigauged them. Then worked out what colour bearings I needed from the workshop manual.

Murray
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I could use the bearings that are on my b16b crankshaft to work out the clearances like you did?
 
jesse888 said:
I could use the bearings that are on my b16b crankshaft to work out the clearances like you did?
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Yeah you could, but I'm not sure if the b16b and b18c have the same journal diameters? Someone will no doubt answer that.:nice:
 
I can check that when the time comes if no one knows.
 
HOLYYY THREAD REVIVAL BATMANNNN !!!

@jesse888

How did you get on in the end?

I've read that many people have built engines with the STD size ACL Race bearings and never had clearance issues but would still like to check.

Surely it's possible to measure the journals with quality vernier calipers? This would seem more accurate and easier than ******* about with plastigage??
 
I used standard size "race" ACLs on a polished crank in the end.
Clearances are alittle large but the engine is fine.
The problem stems from the ACLs not necessarily being the correct size on every journal. The Honda system is colour coded to each journal to achieve the "perfect" clearance.
So measuring purely the journals and assuming the bearings are the correct size becomes an accuracy issue. Personally I found that plastigauge was the easiest method.
 
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