Retune, rebuild, or replace Mercarb?

JMRuth72

Petty Officer 2nd Class
Joined
Aug 27, 2007
Messages
125
Re: Retune, rebuild, or replace Mercarb?

Finding a replacement belt when you have something to go on is easy. First check to see how your belt tensioner works. If it is a manual (IE not spring loaded automatic type) then check to see about how it is set. If it is near the middle of the adjustment range then you can simply measure the width of the pulley, take the belt that you have with you to the parts store and get one of the same length in the new width (the outer part of the belt should be about the same width as the outer edge of the pulley, but it will put you lower in the adjustment range). It might sit in the pulley a little higher but it doesn't matter because you still have some adjustment range. If the adjuster is near it's outer limit get a slightly shorter belt. If it is near it's inner limit get a slighty longer belt. Atleast you have a known length to work with, it is harder when you have nothing to go on. It is possible, but it is harder. What you do then is set the tensioner to it's outer limit and measure around the pulley's with a string in the groove and measure the width. Because the belt doesn't ride in the very bottom of the pully it should put you somewhere near middle range when you put the belt on. Hope this helps.
 

SFT2

Petty Officer 3rd Class
Joined
Nov 11, 2007
Messages
77
Re: Retune, rebuild, or replace Mercarb?

Got a couple of belts by cross referencing the Mercruiser # to Dayco and the width looks right, but they're an inch too short (at least). Didn't have time to discover that until today thanks to lousy weather. At least I managed to get the new tach in.
 

95yj

Petty Officer 1st Class
Joined
Feb 21, 2007
Messages
279
Re: Retune, rebuild, or replace Mercarb?

Dayco's part numbers on all their belts I've dealt with include the length. ie. 5060880 = 88.0" long, 5060875 = 87.5" long, etc. That makes it easier to find the correct length belt for your application once you have the width correct.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Retune, rebuild, or replace Mercarb?

You did loosten and move the alterntor all the way in before trying to put the new belts on didn't you? You also have to remove the spacer on the motor mount to install the belts, did you do that.
 

SFT2

Petty Officer 3rd Class
Joined
Nov 11, 2007
Messages
77
Re: Retune, rebuild, or replace Mercarb?

You did loosten and move the alterntor all the way in before trying to put the new belts on didn't you? You also have to remove the spacer on the motor mount to install the belts, did you do that.

Yup and yup. There's still room for the alternator to move in on the brace, but it hits the block before it runs out of adjustment. If it could have moved in another 1/4" I could have gotten the belt on, so I'm suspecting this is a bigger alternator than original (or at least bigger than the one on the motor calling for the 40" belt). A 41" belt fits fine and the alternator is in the middle of the adjustment. New belt and a spare are on, fired up the motor on the muffs and let it warm up, then leaned out the idle mix about 1/4 turn and it seems to be running stable now. Ran out of daylight before I could lower the idle, though. Oh yeah, got the new tach in, now I just have to figure out if it's set right.
 
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