1963 rude big twin 40 hp model 40353 compression quesrion

[Liam5340]

What should the compression be for this motor? It hasn't ran in years and I'd like to check compression before wasting time replacing impellar and rebuilding carb, also how do I take carb out? Do I have to remove anything to get to carb bolts? Thanks for any info

 

[kfa4303]

Re: 1963 rude big twin 40 hp model 40353 compression quesrion

HI liam. Compression over 100 psi with the cylinders being within 10% of each other should be good enough. Be sure you remove both spark plugs when testing and try to use the electric starter if at all possible. Otherwise, you'll need to give it 7-8 strong pulls. sparying a bit of Seafoam, deep creep or WD-40 into the cylinders prior to testing can also improve compression numbers. To remove the carb, You will have to move the starter out of the way, but it's easy. Here are some handy links to help you decide.

http://www.duckworksmagazine.com/04/s/columns/max/24/index.cfm
http://www.marineengine.com/parts/v...ntage-evinrude-johnson/278448/27844800001.htm