I recently rebuilt both the bottom and top end of my FL350. I performed both a vacuum and pressure leak-down test before installing the Engine. Not long after
Engine break-in I noticed seepage around the base gasket about midway back on the side opposite the belt.
The Engine ran great - still idled fine. I decided to pull the Engine completely out to perform another leak test anticipating I was going to have to replace the gasket anyway. I sprayed a soapy water solution near the leak and sure enough it's blowing bubbles steady until it gets down to about 3psi (not positive whether it stops or just slows at ~3psi - I'll have to double check). I haven't tried a vacuum test yet.
I used the aluminum gasket I purchased from speedshop505 off ebay. I believe the builder scuffed both sides lightly with scotch brite pads and coated both sides with a thin layer of copper spray-a-gasket. I verified the 4 cylinder nuts are tightened to the correct torque spec.
As far as history: I had about 20 minutes on this machine after buying it before it ate a crank bearing and seized. Seller claimed the bottom end had been rebuilt about 5yrs ago but it hadn't been driven much after. When I disassembled it it had the fiber gasket that looked to be in good condition and showed no signs of leaking.
Everything I've read on here has said to NOT use the fiber base gasket. Do you guys scuff the aluminum gasket and use the copper spray? The Engine builder didn't like using the aluminum gasket (thought it was too thin) but I insisted that everyone on this board said to not use the fiber gasket so he did as I requested. I'd appreciate any advice on how to proceed.
Thanks in advance.
-powerchoke