78 140 merc - low power

[wildcatt]

Hi Guys:

I have a 78 Merc 140 I6 on a 16' Sidewinder loPro.
Problematic is an understatement.
Two weeks ago it was idling fine, then it slowed way down. By it's self.
Took it out. It would barley idle, never mind get up and go.
Took to shop. I'm told it had slipped a tooth on the timing belt.
New timing belt. Starts great, idles great. Put it in the lake and take it out.
WOW! it's like a new motor. We go from top speed of 52 before to 59 now.
Hole shot is incredible. I had no idea that could it run like that.
I could even 1 foot barefoot all the way down the lake. I could never do that before as the boat couldn't go fast enough.
OK - so this is great - but the next morning I take it out - still good. I'm coming back to the dock almost idling and it stops. Nothing.
I open it up and the timing belt is fried.
Back to the shop. Mechanic tells me the distributor seized, therefore frying the belt. We hunt down an I6 - 115 for parts.
Now the distributor from the 115 in on. Starts well, but no power when loaded. Just bogs.
Take it back for timing adjustment. Mechanic says - timing is fine. He's not sure now what the problem is.

I'm about ready to take it out to the middle of the lake and pull the plug!

one more thing - I've had the carbs cleaned in the past when this happens and it seems to help - sometimes. Last year I put another power pack on it.

Anybody have any ideas?

Thx

Tom!

[Bruster]

Here's a good place for your mechanic to start::thumbsup:


http://cdielectronics.com/portals/0/downloads/Troubleshooting%20Guide%202006.pdf

[Raceman]

Here's what I'd do: The distributor stuck because the bearings in it locked up. Since it ran god with the old distributor, I'd scatter it and put bearings in it and put it back on the engine. If a distributor igntion inline 6 is ever sunk and the distributor isn't serviced, the bearings are going to lock it up sooner or later, and sometimes they just lock from old age.