R50 engine tinkle

[Ian MacDonald]

I have an 1960 R50 which for the past year has exhibited a tinkle sound from the right hand cylinder head. Over the year this tinkle has got louder. It only appears at certain engine revs,equivalent to 55mph in top gear and dissappears at 60 mph .Cylinder removal does not reveal any problems.Big end and small end check out OK. Rockers and shafts have been replaced. Any Ideas

[phil cheney]

Hi Ian, check the rocker arm blocks on the rocker shafts. They may be pressed too tight on either or both of the rocker arms. Bring it around to compression top dead center on the right side and loosen the adjusters all the way. Move the rockers back and forth to see if they bind. also check the up and down movement of the rockers. You should see oil squish out between the rocker blocks as you move the rockers. I am assuming, Ian that you don't have excessive carbon build up on the piston crown. Otherwise it could be pre- ignition that you are hearing. Best regards Ian. Phil Cheney.

[Ian MacDonald]

Eventually found this problem after some months of investigation. a bit obscure but could be due to pattern rockers not exactly matching the original BMW design. The under side of the rockers was occasionally touching the valve spring, dependand on where the valvespring was in its 360deg rotational path. I had to grind a few thou off the underside of the rocker adjacent to the valvespring top plate to ensure clearance. All now appear to be well.

[Gerry Douglas-Sherwood]

Further to Ian's comments, I had the same problem with my R50, but solved it simply by inserting equal thickness washers (spacers) under the offending rocker block, effectively raising the height enough to prevent the rocker arm and spring cap touching. However, if they were touching then one might expect to hear a tapping noise at all engine speeds. Detonation appears more likely. Check for compression, mixture setting and timing, especially the fully advanced 'F' position with a strobe light.

[Geoff Curtis]

I have also found the problem Ian has mentioned here , of spring & retainer hitting rocker arm , in this case we found that pedistals had been pushed into head, by over tightening of studs, if you check them for hight they should be of uniform hight.
Perhaps these are the butter heads Duane mentioned on another site.Regards Geoff in OZ.