Mercruiser 350 mag mpi distributor timing

[nigb]

Had to reinstall distributor but can't get the distributor rotor to line up with marks on housing. I have no 1 piston exactly on tdc using a borescope camera but when I try & adjust rotor position by pulling distributor out & rotating a tooth either way it won't line up with marks as in pics. Any help on what I am doing wrong appreciated.

 

[Fun Times]

A guide, https://forums.iboats.com/threads/mecruiser-5-0l-mpi-distibutor-proper-clocking.480201/#post-3401176

https://www.bing.com/ck/a?!&&p=c0333b348a85a1a2JmltdHM9MTcyNjk2MzIwMCZpZ3VpZD0zZTA0M2YyYi0yNTg2LTYyN2ItMmRlOS0yZWU5MjQxNDYzZTAmaW5zaWQ9NTE3Ng&ptn=3&ver=2&hsh=3&fclid=3e043f2b-2586-627b-2de9-2ee9241463e0&psq=mercruiser+distributor+phasing+in+technique&u=a1aHR0cHM6Ly93d3cub2Zmc2hvcmVvbmx5LmNvbS9mb3J1bXMvYXR0YWNobWVudHMvZ2VuZXJhbC1xLzU3NzMyNGQxNjUyMjIyNTc2LTM1MC1tcGktaG9yaXpvbi1iYXNlLXRpbWluZy1idWwtMjAxMS0xMXIyLWh2cy1jbG9ja2luZy5wZGY&ntb=1

See if this video helps you any,

Edit: This video should be the better one to watch,

https://forums.iboats.com/attachments/installing-hvs-pdf.87763/

 

[nigb]

A guide, https://forums.iboats.com/threads/mecruiser-5-0l-mpi-distibutor-proper-clocking.480201/#post-3401176

https://www.bing.com/ck/a?!&&p=c0333b348a85a1a2JmltdHM9MTcyNjk2MzIwMCZpZ3VpZD0zZTA0M2YyYi0yNTg2LTYyN2ItMmRlOS0yZWU5MjQxNDYzZTAmaW5zaWQ9NTE3Ng&ptn=3&ver=2&hsh=3&fclid=3e043f2b-2586-627b-2de9-2ee9241463e0&psq=mercruiser+distributor+phasing+in+technique&u=a1aHR0cHM6Ly93d3cub2Zmc2hvcmVvbmx5LmNvbS9mb3J1bXMvYXR0YWNobWVudHMvZ2VuZXJhbC1xLzU3NzMyNGQxNjUyMjIyNTc2LTM1MC1tcGktaG9yaXpvbi1iYXNlLXRpbWluZy1idWwtMjAxMS0xMXIyLWh2cy1jbG9ja2luZy5wZGY&ntb=1

See if this video helps you any,

Edit: This video should be the better one to watch,

https://forums.iboats.com/attachments/installing-hvs-pdf.87763/

Thanks for links. I had seen the 1st video but not the 2nd. The distributor has a flat on it to clear the Inlet manifold so that has to line up. Can't figure out why rotor isn't closer to timing mark on distributor. I had to find tdc using camera as I can't see the front of engine let alone a timing mark on pulley. Why boat builders make the engine bays so tight is beyond me!

 

[Candy Gramformongo]

Is it possible that you are at tdc on the exhaust stroke, not the compression stroke? That will throw you off half a tooth if the distributor gear has an odd number of teeth.

 

[nigb]

Is it possible that you are at tdc on the exhaust stroke, not the compression stroke? That will throw you off half a tooth if the distributor gear has an odd number of teeth.

Thanks for reply. With camera I could see no valves open with piston coming up to tdc. I rotated crank 180 deg to check & I could see exhaust valve open as piston came up to tdc.

 

[nigb]

After gathering my thoughts I remembered I had marked the position of distributor body previously when removing it & the marks were still present. I was probably being a bit pedantic in that the flat on distributor had to be parallel to the Inlet manifold when in reality it isn't on my engine as in photo. Thanks for your replies they were useful to me.

 

[QBhoy]

Hi. Literally just done this with my boat. You need to make sure the bottom crank pulley is absolutely at the tdc markings. On the compression stroke too. Can be done with watching a compression gauge if required.
Then. You need to look for the line or marking on the distributor shaft. Make sure that lines up with the lower notch on the shaft. This will make sure the rotor is retarded 40 degrees or so. Then when you sit the shaft down into the engine, locking with the oil pump slot, the helical gears will then engage home, rotating the rotor forward 40 degrees again as well as pointing it to the wee notch on the diz plastic base that says “8”.