Re: 1973 Mercury 9.8

Posted by Chinewalker (24.97.102.12) on January 30, 2004 at 10:47:35:

In Reply to: 1973 Mercury 9.8 posted by Dr. Ken on January 29, 2004 at 14:02:01:

You'd be surprised how many people want to juice up their motors to gain more power, when the motor isn't even putting out its rated power. Figure on this - your motor is over 30 years old now. I don't know how much it was used, or how well it has been maintained, but I can tell you what I've seen as being fairly typical...

Your motor likely has a fair amount of carbon sticking to the top of the piston crowns, and likely some has worked its way into the ring grooves. It's also likely there's a fair amount of carbon in the exhaust ports and the exhaust chamber, which results in lessened breathing capacity - what goes in must come out.

Also, is your motor set up with the proper propeller for your rig and load? Does the motor come up to the max RPM (around 5500 revs)? Is the prop in perfect shape?

What condition is the powerhead in? How's compression? If the motor has low compression in one or both cylinders, it could be tired and in need of re-ringing. If the motor has ever been overheated it may have scuffing to the pistons and bores, which eats up compression.

Lots of little things to look for to assure yourself that you're getting all 9.8 rated ponies...

Have fun!
- Scott