Timing Belt Install on Mercury 650 (1970 model) - Advice on Installing & Distributor

[scottwoodward]

Timing Belt Install on Mercury 650 (1970 model) - Advice on Installing & Distributor

After putting back together my 650 and trying to start the engine, I managed to blow the timing belt. I knew I wasn't getting any spark, but couldn't figure out why until I flashed a light and saw that the timing belt was toast. It was in good shape before I took the engine apart for a tune up. I fear I may have somehow put the distributor on too tightly, with the screw that attaches the timing belt pulley and the distributor. Just ordered a new timing belt, but would welcome advice on making sure I install the timing belt correctly and make any necessary adjustments to the distributor.

 

[GA_Boater]

While waiting for the new belt, spin the timing pulley to check the bearings.

I had a bad one and the belt skipped a tooth, throwing the timing off while out on the lake one day. I checked timing, put the belt on the right teeth and eventually my belt looked just like yours.

You can't install the distributor too tight or the pulley screw. either.

 

[scottwoodward]

Need Help with Timing Belt Install Steps

I blew the timing belt on my Mercury 650. When putting the engine back together, I must have made a rookie mistake in how I put on the distributor and how I attached it to the pulley by the flywheel. The timing belt was fine before putting things back together. It was in good shape. See video below - distributor movement is stiff and doesn't seem right. I'm piecing together the steps to replace the timing belt, but I could certainly use some expertise advice on the steps to do this right.

https://drive.google.com/file/d/1acVqsFzZBQIz20pj3yDFaMY98BNc6dZX/view?usp=sharing

 

[GA_Boater]

Why did you start another thread?

You have a bad bearing or the rotor is rubbing the cap. Need the serial number of the motor. There are some expensive parts inside you don't want to break.

 

[scottwoodward]

Motor serial is 2804270.

 

[scottwoodward]

Well, I think the mystery about why the timing belt blew is solved. I don't know how I managed to do it, but somehow in putting on the distributor, I managed to jostle the distributor key loose. It ripped up the bottom of the pulley assembly. The top bearing assembly seem to be fine. No sign of any of the shards penetrating the seal.

Will still need help with the steps to put on a new timing belt. This whole project has been a tough, but worthwhile learning experience. Very good way to get to know the engine.