mercury 300 thunder bolt cooling qu.???

[racing fan]

Like I said in previous post I got a 300 thunder bolt motor 4 cylinder for my hydro. It hasn't been run in over 5 years, though the other day I finished going through it doing basic stuff like looking the water pump over and stuff. There is a pipe (copper) that goes from the water pump when the lower unit is bolted on to the water jacket for the power head so I hooked a garden hose to that and started the engine. I started right up 2nd pull and sounded very very mean like a rich kids parents ski boat. (cigarette boat)

Now the questions, there is a exhaust port in the mid section just under the power head is water suppose to come out there? and the mid/lower unit?

yes, I did start it and ran it for 10 sec or so because I did not know if it was cooling right i used (16:1 oil ratio) because it hasn't been run in a long time

look at this vid I am talking about this port where the water is coming out, but its not the same engine

http://www.youtube.com/watch?v=Vv6JHZMqbQM

[pistnbroke]

yes ok to run that way provided you have plenty of pressure and the tell tail is going good ..yes water from that orifice is correct..cut the oil ratio to 50 to 1 or you have in effect weakend the mixture and may carbon up the motor /foul the plugs and get pre igniton

[racing fan]

OK well i have got a better seal on the pipe and water is coming out in the right spots now

today i switched the oil ratio back i only went that high because it hasn't run in 5 years and we only ran it for a grand total of 1 min lol

[racing fan]

what oil ratio should i use 25:1 ???

[jacktheroof]

Having a Merc 300 Thunderbolt myself,I tend to run on 35 to 1.It's in the safe zone,but with 50 to 1 you're using a mix only suitable for 2stroke race engines,go-carts etc...I would hate to say ( I told you so ).Stay safe,it's a lovely engine and yes,they do sound nice.We are the lucky few to own one.

[racing fan]

almost all outboard motors now a days use 50:1 not just race 2 strokes and most go karts are four stroke but...
you think I should run it 35:1

[jacktheroof]

Your right about most go-carts being 4strokes,but going back to the 300 Thunderbolt 1960,you'll find that 25-1 has to much oil and will only blacken your plugs and throw the timing out,not by much,but you'll notice on pick-up.Try 35-1,you don't get the heavy smoke when you throttle up, when you throttle off,there's only a fine haze (sign of a well tuned engine) only you can decide what's best for your engine,but it's worth cleaning your plugs and giving 35-1 a go,for half an hour as it takes a bit of time to burn off old oil.

[racing fan]

yea ok 35 :1 sounds good some say 50:1 but the oil i don't think is that good now a days they ran from the factory 24 :1 so now a days standards 35:1 sounds good but i only ran 16:1 for a bit I only have put 1 oz of feul through the engine just because of the 5 years with out lube or gas