What's the best way to find a dead cylinder?
good lord. how was that even running with that amount of leak down.
anyway 6 & 3 are no bueno
it's a hard call with the spare motor. do you know if it was a good runner when pulled? how long's it been sitting? can you roll it over and get a quick and dirty compression check or leakdown?
if i could run some baseline on it and the test results met my criteria i'd be inclined to snap it in and run it.