Distributor Cap Issues

[62cruiserinc]

I'm trying to replace the ignition parts (dist cap, points, etc) on my 1981 Sea Ray 260 with MCM 260 (5.7L) engine. I bought the boat 3 years ago and haven't replaced any ignition parts yet. The previous owner says that a new crate engine was put in.

All sources I can find say that this engine from 1978 to 1982 had a Mallory distributor. The correct cap for a Mallory distributor is Merc 391-5075 or Sierra 18-5376. The boat came with some extra parts in a box, including an old distributor cap in the box for the replacement that the PO put in. The box is labelled Sierra 18-5369. I'm not at home right now, but I had my son take a picture of the cap on the engine and the old one in the box and comparing them to online pictures they are indeed a Sierra 18-5369.

Now I don't know if the original Mallory distributor was moved over to the new crate engine when it was installed. It's possible a different distributor was used for the new engine. Online pictures show that the Mallory distributor uses the 18-5075 cap.

The pictures of the cap on the distributor seem to show that the Z-shaped hold-down brackets don't fit up well against the side profile of the cap, even though they seem to be holding it down OK.

Is it possible a wrong cap is installed somehow?

How do I tell if it's really a Mallory distributor? I looked at online pictures and there is a metal "Mallory" tag with a model number on them. I don't know if mine still has the tag, I will look when I get home.

Any suggestions would be appreciated.

Thanks
Steve

 

[Bondo]

Now I don't know if the original Mallory distributor was moved over to the new crate engine when it was installed. It's possible a different distributor was used for the new engine.
I don't know if mine still has the tag, I will look when I get home.

Ayuh,..... If you can't figure it out when you get home,..... post pictures of what you've got,......

Til then, there are no answers,....

 

[62cruiserinc]

Well, I got a surprise when I went home and pulled the distributor cap.

There was a Pertronix Ignitor conversion kit in the distributor instead of points!

There was no name tag on the distributor, but it sure looked like a Mallory based on photos online.

The "incorrect" cap for a Mallory distributor was on it.

The cap fit snugly, but the clamp profiles did not match the distributor shape. The cap was snug with the screws and metal tab.

The cap looked in very good shape, the center button showed almost no wear.

Looks like I don't need some parts I thought I needed.

Notice the funny angle on the cap hold-down in the picture.

Steve

 

[62cruiserinc]

Here's a picture of the Pertronix in the distributor:

 

[achris]

Yes, looks like an automotive cap. Replace it with the correct MARINE cap, and you'll need to replace all the HT leads too. I suspect someone in the past bought a new set of (automotive) leads, not realising that a marine cap has different terminals to automotive, so they found a cap that 'fits' and slapped that on.

Chris.......

 

[62cruiserinc]

According to the box that the previous owner left with the boat, and looking online at pictures, the cap is a Sierra marine cap, just not the one that should fit the Mallory distributor (if that is what the distributor manufacturer is I still am not sure).

I could buy the "correct" cap and see if it fits, or I could just leave it alone as it seems to work fine.

Steve