Mi16 Bottom End Resurrection Advice

[MVK 0]

Hi guys

 

I've got an Mi16 on my bench which has spun the 2nd cylinder big end bearing. This is my first engine rebuild and first Peugeot so some advice is needed if possible. The crank pin of the second big end is ovalised, with the least worn area being 50.00mm (std) and the most worn at 49.56mm (most worn where piston is at peak and trough of stroke). The crank pin minimum limit for oversized Mi16 shells, after regrind, is 49.684mm, which would mean my crank pin is worn beyond service. I've seen T16 bearings come in +0.50mm and +0.80mm. Can these be used/ has anyone used these when their Mi's have gone through a chunk of crank? The area that is worn to less than the 49.684 limit is pretty small, probably about 15mm long, between the webs. It just seems a bit bodgy to have the crank ground to 49.68mm and have a section that is undersized still.

 

I've also considered fitting an 8v crank as 16v ones seem hard to come by, does the lack of double-counterweights have a severe effect on anything?

 

Any other advice?

 

I think i'm going to replace the con rods anyway as the No2 rod is worn to almost 0.50mm bigger than the others. Any recommendations where to get these/ all other parts for reasonable prices? Student budgets make things tougher haha.

 

Thanks in advance,

 

Matthew.

 

 

[welshpug 1,620]

there are some diesel bearings available in +0.50, depends whether you have lost all of the 0.316mm off one side of the journal.

 

easy to find another 88mm stroke crank that'll go in however, you can use the 8v and the xud and dw cranks, these are quite plentiful.

 

i doubt the lack of counterweights will be noticed by many, the Turbo diesel cranks are forged units and have been successfully used in very high spec engines, most notable example that springs to mind is Colin Satchell's Sandy Brown XU10 hybrid Hillclimb emgine, circa 270 bhp at over 8500 rpm iirc.

Edited May 2, 2016 by welshpug

[Miles 331 1 Cars]

If you can find some old stock ACL bearings they went to around .8 under from memory, King bearings are what most use now but without checking not sure of what sizes are available, This T16 bearing thing is rubbish as a bearing is a bearing and you want the older lead/copper ones are better than the alloy ones now

 

Cranks and rods, stick a post in the wanted section

[Chipboy 0]

ACL are back in trading aren't they?

 

http://www.acl.com.au/

[petert 549]

If you're a bold designer, the other thing you can do is change to small block Chev V8 small journal size, which is 2.0" (50.8mm) standard. There are a heap of undersize bearings available however, in a range of qualities. They're cheap as chips. Just look on eBay. And remember, you get two rebuilds out of one set.

Edited May 3, 2016 by petert

[petert 549]

ACL still list the 4B1670 in 0.5 and 0.8 under.

[welshpug 1,620]

is that not the wrong way? you want something below 50mm if you want to overgrind a 50mm journal?

[petert 549]

2" - 0.050" = 49.53mm

 

Little point though if you can still buy 4B1670.

[MVK 0]

Wow! Thanks for all the advice, definitely got some more info to work with. I've found a lad selling an mi16 crankshaft which I'll probably try and get off him, as according to him it's pretty good nic, and probably a better starting place than mine if it needs regrinding.