50hp Compression

woollums

Cadet
Joined
May 20, 2008
Messages
14
Im about to test the compression on my 04 Mercury 50 and i need to know what the compression should be? Also i guess i test at WOT?
 

1nebel0

Chief Petty Officer
Joined
Nov 28, 2005
Messages
512
Re: 50hp Compression

You don't say what year it is as the older units had more compression than the newer ones.. I would guess around 130-140 would be normal..You are looking for uniformity rather than a large number... The bigger V6's come in around 125lbs....My racing Bridgeport V6 has 120 however higher compression means the need for more octane and less timing given our crappy Ethanol fuel...so don't be impressed with higher numbers..Could be loaded up with carbon increasing the numbers and causing harm to the motor...Anyway, look for the cylinders to be close to each other and if not SEAFOAM...look up the procedure as it us truly an unbelievalbe product that helps bring the cylinders back in line by reducing carbon build up on top of the pistons...Also helps to clean the rings that can keep them from sticking in the grooves causing loss or uneven compression...Lastly, you can do the compression cold however the book always wants WOT-warmed up.
 
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