As I am building a set of 540's I have a question even though its basically covered from past engines with no issues...

way back when I knew zero about BBC and boat engines, I have 454's in Baja with bigger clearances and only 55psi oil pressure, wiped mains out 3 times before I realized it was my pressure issues with clearances not the filters, fitting, and type of bearings like most here said.... I set them up the last time with new uncut cranks, 1-4 mains were .0030 and the #5 main was .0035 if I remember right, rods I think were .0020 or so, I do not have my note sheets anymore, sold them with engines but thats what I think it was, had 75 PSI oil pressure with a Melling HV HP pomp with shimmed spring, never had a bearing issue again, no temp issues... NOTHING, many WOT runs at 5000 rpm

So, in my 540's I am figuring the same, but also wonder about cam gear issues, I never had before but I plan to spin these at 6000 rpm, will I want that high pressure with a larger clearance?

what do the ENGINE BUILDER guys do? clearance and pressures...I wanna see if I am on track with how I plan to build and run these clearances and pressure, I normally set them up as my buddy recommends and he has a perfect BBC 800hp track record, I just want opinions from guys that build marine engines, not car and not what they read...

I ran .0025 rods .003 mains with hv pump over 90psi with billet cam and melonized gear and grenaded the gear. This was with a out of the box msd distributor and marine specific big money gear. Previously I ran an msd distributor with slip colar set depth little lower with 0 issues/ wear on gear but the slip collar slipped distributor turned ended in a big boom. That's why I changed over to the standard distributor. After all that we machined a little off the fixed collar on the distributor put on a bronze gear (that's all I could get my hands on at the time) and ran it. Upon disassembly the bronze gear was perfect. Had the gear been melonized I think it would have had the same results. Gear mesh is absolutely critical with a Hv pump in my opinion. I think a standard pump is a little more forgiving. I'll just put this out there because I didn't know this but stumbled across it in my research/ travels. They actually do make distributor gears in different diameters. Something like this +.005, + .010, +.015 I was told that the little bit of extra diameter can make a big difference. Hope my experience might help you out so you don't have to get towed in like me...

yes, I know the gear has to be right, my buddy sets them up somehow and checks all that, beyond my abilitys lol distributer depth is for sure critical and helps control pressure too I had that issue with Baja engines, one was off a tad, he did something with distributor and fixed it, said it was a depth thing I think.

Go big or go home Tim!

Errrr, that's probably not good advice for this thread. It seams this is part of the secret recipe for most shops...

.0028-.0032 on mains, leaving the rear thrust a little on the high end
.0024-.0028 on the rods coated clevite bearings
M77 hv pump 70-75 psi cold. Never had issues like this. Big blower motors a little different but 454, 502, 540 like the above

hahahah

Seems to be what I was looking at, like I said I think my rod numbers were off lol