TOPIC: 99CI casting number

A friend of mine has what he thinks is a Mercury 1500. He is unsure because the wrap and bottom cowling does not match. Wrap is red band bottom is blue. The casting number in the block is 852-5264. His serial number is 3752986, which if it was a 1500 would make it a `74. If its not a 1500 that would change. Does that number say what the block is? If you removed a transfer port cover I guess you could see if it did have power porting and therefore be a real 1500?
Thanks!

Randy

You could remove a transfer port cover alright, but I found a similar old discussion at Screamandfly, where someone suggested pulling a spark plug, and positioning that cyl's piston all the way to the bottom of its stroke.

At that point the power port is just barely visible if you peer into the cylinder with a flashlight. A lot less wrenching if it works!

Another easy thing to do would be to pull the main jet plug on an accessible carb, and noting the jet size. You should be able to read the size marking on the jet without having to remove it.

Looks like a longshaft would use .080" jets and a shortie, .082".

A 115 would have .072" mains.

From what I can gather, it's either a 115 or 150 for sure. Power ports and main jets will tell!

HTH.........ed