How do you set up timing belt on 50hp merc '75?

[shakespear]

have just fitted new reed blocks and ring to the poorly old merc I have the pleasure of owning.<br />How do go go about setting up the distributor drive belt.<br />have set it with no1 piston at TDC and the two lugs on dissi lined up is this right and if not how is it supposed to be done?<br />thanks in anticipation<br />SHAKESPEAR

 

[clanton]

Re: How do you set up timing belt on 50hp merc '75?

Need more info. Model of engine 500,650, number of cylinders, CD ingintion or points.

 

[shakespear]

Re: How do you set up timing belt on 50hp merc '75?

Clayton its a 1975 50 500 4cyl. <br />no points that i know of<br />has a dissy with 4 wire that come out to a black box at front of engine cassing.<br />thanks <br />shakespear

 

[clanton]

Re: How do you set up timing belt on 50hp merc '75?

The book I have does not show a 500 with a distributor. Post serial and model number.

 

[shakespear]

Re: How do you set up timing belt on 50hp merc '75?

Its a 1975 50HP 500 S/N 9082764.<br />has variable timing (ie dissy moves round with first part of throtle movement)<br />If you have a book is there any chance of the of the ISBN number off of the back of it so i can order one<br />Thanks again<br />Shakespear

 

[12Footer]

Re: How do you set up timing belt on 50hp merc '75?

They all used the same timing belt on all 3,4,6 cylinder models. It is merc part#20140.<br />Here is the cheapest place I have found it online.<br /> http://www.oldmercs.com/ <br /><br />To install it,unless you marked the flywheel,pulley top cap,dist and decal, you will have minor timing issues.<br />But you will still get it "ball park", if you<br />set it to TDC. I use a pencil with a rubber eraser in the #1 spark plug hole,and rotate to TDC. Then, you'll note a small pointer on the top pulley cap. It will ony fit the cog part of the pulley at one spot.<br />Install so that the pointer is pointing to TDC (0-degrees) of the decal. Once you know the engine is running well enough to operate under a load, take it out with a bud and a timing light, and set to spec under load.<br />Good luck.

 

[clanton]

Re: How do you set up timing belt on 50hp merc '75?

The nr is NSBN 0-89287-396-5 , but does not show that engine with dist. What kind of marks on flywheel?

 

[JasonJ]

Re: How do you set up timing belt on 50hp merc '75?

I don't know about the newer outboards, but my 63 inline six has clear marks that you line up. There is a mark on the flywheel, and a mark on the distributor wheel that point towards each other when it is right. the mark on the distributor is on the toothed wheel itself, you can't miss it. Can't image Merc would change from such a simple setup on its belt driven distributors over the years. Good luck.......

 

[12Footer]

Re: How do you set up timing belt on 50hp merc '75?

Yes, Jason,It's pretty much the same (omly less cylinders). The only thing i didn't like about the ones I werked on, was the rotor and dist shaft were bonded....Yuk.

 

[shakespear]

Re: How do you set up timing belt on 50hp merc '75?

thanks all the problem all started when i had to strip the fly wheel to get it off.<br />sorted it.<br />put screw drive down on top of piston no1 felt it move to top of stroke then positioned fly wheel to nearest bolt holes pulled it and it went first time <br />Thanks for all the help<br />Is anyone any good on prop sizes????