Main Cap Washers (?)

[2002#3]

The M10 block I am assembling came with thin plain washers on the main caps.  I have read on FAQ three versions of such washers: 

  (i) BMW did not use washers.

 (ii) BMW used plain thin wave washers.

(iii) Use the thick heavy washers like those used on the head.  

 

Opinions, please.

 

Thanks

[2002iii]

Realoem.com shows wave washers.

[OldRoller]

Looking back at my block assembly there are thin wave washers under the main cap bolts. Original to the engine, first time it was invaded since March of 1974 build.

[TobyB]

A hardened wave washer would normalize the friction between the bolt and the washer.

 

t

use motor oil.

[Götesson]

Interesting...Would like an answer from those who build race engines here. If they use these wave washers for their engines, or they run without. Because not everyone runs with ARP, I think.

 

Something that is quite interesting is that in the S14 engines there are no washers, but the same bolt 11111735525 as for the M10 and many more.

 

Am in the starting pit to start building my race engine, so it would be interesting to have some input here.

[tzei]

Well I don’t have washers in my race engine.

[John76]

1 hour ago, tzei said:

Well I don’t have washers in my race engine.

Yep ... every pound matters on a racecar 😁

[Son of Marty]

You'd need a good sized pile of those washers to make a pound, but I do agree that you need to save ounces to make a pound.

[kbmb02]

I use new wave washers on all my M10 street and race engine builds, with an oil ‘blend’ on the hardware. OEM bolts. -KB

Edited April 11 by kbmb02
updated to “new”

[Schnellvintage]

I have used wave washers on every engine I have built also. I have never had an issue with the main bearing cap bolts with wave washers.

Building M10, M30 and M20 engines since 1989.

fwiw,

Matt

[Tommy]

10 minutes ago, Schnellvintage said:

I have used wave washers on every engine I have built also.

Same here but I have had quite many of the wave washers crack in two pieces so I do see a point getting rid of them inside the engine. Not sure if any of the failures occured on the main bolts. Anyway, using the wave washers couple of times is ok but several times, not so good in critical places.

[TobyB]

I'll look next time I'm inside one of mine, but I don't think I do use wave warshers.

 

Byron, we're waiting for you to admit what you do...

 

t