Help replacing Rotor in 1967 Mercury 950 SS Please

When I was out on the water my distributor cap came loose while at full throttle. Since that happened it bumped up against my Rotor and the Rotor shattered.

I have ordered a new Distributor Cap and Rotor that will be here tomorrow or the next day. In an unrelated note I have remodeled several houses, one of which was abandoned for 30 years, so I am good with my hands, but I am clueless when it comes to motors.

How can I replace the Rotor and Distributor cap? What are the steps?



Thanks!

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

BUMP please

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

Well, it looks like you are about half way. You already removed the cap. To change the cap you'll have to remove the wires. They are threaded into the cap, do not try to pull them out! The center coil wire is also threaded into the cap, but should pull out of the coil. The broken rotor is most likely bonded to the rotor shaft with loctite. Since its already broken, remove it anyway you can, just don't damage the shaft. I would recommend removing the distributor housing by removing the 4 bolts on the top. That way you don't have to work upside down, its your choice. I would recommend putting a few drops of blue loctite (242) on the shaft before installing the rotor. Also, take note what wires go where on the cap. The wires should be labled, the cap might also be labled but have 3 different firing orders. Take note before you go removing wires. I would recommend doing one at a time.
Good luck

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

Hi,

I followed your advice and removed the wires one at a time and put them back on one at a time.

The distributor button the guy sent me out looks identical but the shaft end is different, the one I had is a half circle, the one he sent was 4 splines, the button looks identical though. Is there a way to get the broken button off and re attach the new button onto the old shaft?

In other words is there a way to dissolve the old glue or loctite?

Thanks!

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

Can you post a picture of the two different parts? When dealing with loctite on bolts, you can heat the area to release the loctite, I don't know if I would want to do that on a rotor. If you can apply even pressure around the base of the rotor near the shaft it should release. Use caution.

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

The rotor is molded onto the shaft so here's the view of it and the instructions, the cap (6) is a little difficult because of the tabs that lock it. I used a punch to bend them away.

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

The rotor is molded onto the shaft

Click to expand...

On this model it(rotor) is removable with the special rotor puller pliers part # 91-32477A1...

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

Thank you all for your help and advise. I will try to remove it via either the special tool or heat.

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

Faztbullet said:

On this model it(rotor) is removable with the special rotor puller pliers part # 91-32477A1...

Click to expand...

I beg to differ! This is not the old-style dual-point distributor model, it's old-style electronic ignition with a "horseshoe" shaped trigger (same as used in some Mercruisers), and a short distributor/rotor shaft, with the rotor bonded to the shaft.

The distributor diagram and instructions posted previously are for the newer-style trigger and not applicable to this ignition system.

Here's a link to the diagram and parts list for the 950-SS electronic ign:

Mercury Marine 950 (6 CYL.) DISTRIBUTOR ASSEMBLY, COMPLETE (MERC 950E-SS-1) Parts

(4) 1/4-20 bolts hold the distributor trigger/rotor housing assy to the distributor drive. Once the housing is dropped, remove the screws (with Nylock nuts) holding the distributor cap adapter (part #10) to the distributor housing base (part #1).

Be sure to note the orientation of the parts, it may help you get it back together later. As I recall, once you split everything apart, the trigger (7) unscrews from the base. The trigger holds the rotor and its bearing into the housing.

Note the trigger shim (6), wavy washer (2) which goes between the ball bearing (3) and the cavity in the base. It provides a bit of pre-load to the bearing so it doesn't tend to move up and down in the housing.

Retaining clip (4) holds the bearing to the rotor shaft assy. It's a slip-fit as I recall.

To reiterate, the rotor is not removable from the shaft assy; it's integrally cast. I can't recall if the "chopper" disk is removable, maybe once the bearing is pulled, but I'd have to take a look at one, it's been a while. Probably not, since they list different rotor assy's for the 4-cyl and 6-cylinder.

So, if you try and separate the rotor from the shaft, you'll destroy it!

The rotor assy is NLA but the guys in the above link still have 2 in stock for only $125 each!

Here's a new 393-2921A 7 rotor assy on eBay for $80 shipped:

New Mercury Mercruiser Force Quicksilver Rotor Shaft Assembly 393 2921A7 | eBay

I would contact the seller and ask for a picture, just to be sure.

HTH & let us know how it goes.........ed

p.s. it might be a good idea to post a pic of the rotor assy you ordered/received, along with the old rotor assy. Maybe we can figure out what's the issue with the end-of-the-shaft. Whatever you've got has to be able to engage the upper portion of the distributor drive (the part driven by the timing belt).

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

Your correct as I missed the SS in posting....as you get older its hard to keep 40+ years of info from getting jumbled in ole brain pan.:joyous:

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

Faztbullet said:

Your correct as I missed the SS in posting....as you get older its hard to keep 40+ years of info from getting jumbled in ole brain pan.:joyous:

Click to expand...

Yeah, I know the feeling, sometimes it's hard to get the remaining brain cells all firing at the same time! :sleeping:

Re: Help replacing Rotor in 1967 Mercury 950 SS Please

jhouser said:

Thank you all for your help and advise. I will try to remove it via either the special tool or heat.

Click to expand...

the rotor can be repaired.....done several.....plastic epoxy.....