its hard to tell you've done the easy test and have the best gauges try hooking a mech. gauge at front main on block and tell me what it is ,,,it sound like bear in motor hurt somewhere maybe due to gas thining ,the filter should show trash in it though ,,///was any metal in drained oil did you drain from pan or suck it out dip stick ????

I suck the oil out dipstick, can't get to the drain plug {Cig. Bullet}
Where do I tap in to get a reading from front main?
Will the presure keep getting worse if thats it,or will it come apart? Never lost a main before......

I had a 91 bullet and loved it you tap the front main on the top of pan rail its and allen head plug 1/8 roughly

I could drain mine from the plug in a bag

it gets worse to a point then it pops so get that plug out and
install that gauge :D :D :D

Thanks Bobby...I'm on it !
I'm thinking now....If I do need to pull it it may be time now for a new short block......I have Mark IV blocks...GM cranks already 60& 60 under. The blocks are 60 over....What can i run without changing exhaust {stainless marine} & Intakes { The Blower Shop}...Also keeping my Mech fuel pump...Merlin ?
Do you build Short blocks ? I think i would feel better with new bottom.

Yes, Merlins have bosses for mech. fuel pumps.
Got two of them puppies in mine:cool:

Hey bird dog I like merlin or Dart blocks and Build alot of short and long blocks for Boats / Mo-power is right they have the bosses for the pumps and are very very tough blocks ,,pm ,me if I can help I have both in stock