Rocker Arm without Oil Bleed Hole

[mwagon]

Just had a BT7 Tri Carb engine rebuilt & while setting the Valve Lash, noticed one of the Rocker Arms beside the Oil Return Line had the upper Bleed Hole covered by a weld. Was this typical from factory, or has is this a modification that someone else has done? Not sure for what reason.

 

[Randy Forbes]

Some clown welded (or brazed) it shut, instead of rebuilding the rockershaft.

I recently rebuilt an early BN4 (Longbridge 2-port) that had all twelve (12) rocker arms with the oil holes brazed shut. This car was bought from a high school shop class in NM or AZ.

Half the rockers w/brazing ground down, prior to redrilling oil holes:

Upon return from Rocker Arm Rebuilders:

After polymer coating (dry-film lubricant):

 

[mwagon]

Thanks for the great detailed response.
Would you know if on a OHC engine with solid lifters would the Dry Film Lubricate wear well on the portion of the Rocker Arm that contacts the cam?

 

[Randy Forbes]

Any two (2) surfaces that slide and/or rotate against each other would benefit from the polymer coating; the dry-film lubricant results in an oil retaining surface.

 

[Randy Forbes]

This is a DOHC 4 v/cyl 3.2 Litre BMW ///Motorsports engine that had EVERYTHING polymer coated (including thermal barrier, thermal dispersant, oil shedding and dry-film lubricant). This particular engine used hydraulic lifters, so they couldn't be coated (media contamination concerns) but their bores and lobe surfaces were coated with DFL.

This entire process (engine removal, teardown, surface prep, coating application, reassembly and reinstallation__952 pictures__) can be seen at: https://www.spcarsplus.com/gallery3/index.php/Tweety_Two