I have a pair of merc 1000 and the blower belts seem real loose. I understand a motor when hot will increase in height but whats a good guide line to go on how much tension should be on them cold?
Also where's a good place to buy a spare blower belt?
I heard the grooves in the belt are called something specific (teeth)?
Is there a classification to how close the grooves are or the amount on the blower spline?
How do you know what belt to buy (grooves, thickness, length)???
Is there a better name brand belt?
How to know when the belts are wearing out?

Thanks for anyone taking the time to respond...

their are 2 types, cog and groove( i think thats the proper name). as i ve been explained their should be about 3/4 to 1"of play from side to side on the slack side. this may not be text book but a couple of very reputible engine builders said this is proper.
if they are merc then call merc.

gates is another.

and the old belt should have some legable numbers left on it to match up.

as for wear you can turn the belt inside out and bend it and look for cracks, and any obvious signs of wear , tears or missing segments.

good luck.

Thanks for the response Monstaa. You've answered a couple of my questions over the last few years and I really appreciate it.

Good advice on calling merc. Funny thing is I didn't think about calling them.

3/4 to one inch is spot on, it seems like a lot but stare back there at 6000rpm and it wont seem like it is much.....

What........Am I chopped liver?? Call me on that stuff if I am going to be servicing that bad boy.