Originally Posted by lmsport
The difference in spring tension between the M55 and the M55A is not great, but the oil pressure goes up about 15psi. I think you will see more than that. I have put the pan on with a couple bolts and some oil and run the pump with priming tool just to see what the pressure is doing. I expect to see about 70psi on a cold engine with the priming tool and Mobil 1 10-30. As long as you have made a oil groove on the distributor body to spray on the gear mesh location, I think you will be OK.
Reading the article of the relief spring, they say that drilling a larger hole by pass passage way is needed to ensure an adequate oil bypass during cold starts and high rev pressure conditions, so can you explain better how does this work because i believe i'm missing something...