manifold pressure

[pinkham89]

hey all, getting out the old 50hp (model 50ESL71S) jonny and giving her the good 'ol once over revealed that it's time for a general tune-up/rebuild of the carbs/waterpump/ignition system.

I was wondering if anyone knew how much vacuum each carb (or maybe the intake itself) should be pulling (somehow that terminology doesnt seem correct....)

I do have the sync gauges but was looking for the spec.

Also, what else should i be looking for to replace/check over? I have no idea what has been done to this so im thinking that replacing all fluids/ water pump/ new plugs, check on the rubber and the wires is a good place to start...

 

[1946Zephyr]

Re: manifold pressure

Well, manifold vacuum pressure on these engines is not really one thing to check, but rather compression is. Compression on one of these engines should be very close to the same on both cylinders. If they vary, then it would be time to see if possibly you have scoring on the cylinders/pistons, or possibly a bad reed valve. Reed valves very rarely go bad on these engines, but it is very common for scoring on the pistons to affect the compression. This can easily be checked, by removing a bypass cover on the intake side of the cylinder and then you can get a visual of the pistion, through the port.

Good Luck. I hope this helps