BBC
Thanks for the couple PMs about the Big M block having restrictor plugs behind the front oil galley plugs, instead of the rear like on OEM blocks.
I contacted the builder of this engine, who does some machine work for me, and he said he did not install any restrictors.
On the Dart blocks I have built, there are 1/4" pipe threads behind the 3/8" pipe plug threads in the front oil galleys that can be used to put drilled plugs to restrict upper oiling, but Dart does not have those plugs in place, so they would have to be added if desired.
The piston oilers that were special order for this block, and specified by the owner, are eight 1/6" holes drilled to splash oil at the under side of the piston domes. That is oil volume that reduces the oil avalable to go to the top side?
I just don't know if the previously mentioned lifter modification could help. Dart tech is the source of this I was told by the owner.
I did not have this issue on the Dart blocks I dealt with previously.