leakdown/compression specs history

[Biggus]

On a 4 stroke, it should be done at TDC compression stroke so both valves are closed. It's a time consuming process.

When I do a leak down test, I pull the valve covers and pull the rockers so all valves are closed.

[npartin]

never thought of that... that makes things go faster... and only have to go 1 full rotation versus 2 or more to get all the cyl...

race 51 royal purple is SIMILAR in wt as 20/50W BUT it is actually closer to 35/50... just because its got 500 hp doesnt mean that it needs more oil thickness.... besides a lighter oil will cool the engine more and actually allow for better more consistant lubrication due to its abilty to get through the journals and tight tollerances easier than a heavy oil... ESPECIALLY when cold.... and oil in 145-160* engines to begin with doesnt get very warm..... THEN add in the fact that yu all run oil coolers....... oil temps around 120-160 arent all uncommon.... which means that the oil is THICK and may not slide through the .0025" clearences as efectivly as say race 41 (15/40) or even a true 10/40 10/30.. and when does all the wear occur in an engine.. AT STARTUP!!!! not on top or at peak TQ... its when CHIT is dry..... and lacking lube...