Ignition question
 

Can a distributor on a Mark V be used on a Gen IV engine....both engines have Thunderbolt IV ingition.
Longtime member Xcel just called me and is hoping for an answer....apparently he is getting some oil up in the distributor...something about the breathers not being quite right??

I used a MkIV distributor on my Gen 6, so I see no reason why a MkV wouldn't work.

The difference is the gear on some models
 

A Mark IV and Gen V have the same dist. but a Gen VI has a steel roller camshaft and needs a hardened dist. drive gear.
Sincerely
Dennis Moore

Dennis,

I just recently heard about the problem from another member who had to rebuild his engine after the original gear failed and jammed up a screen inside the engine somewhere. The oil pump or something like that basically was clogged with metal from the distributor gear failing.

So I have to remove the Mark IV distributor and install a hardened gear on it for my new Gen VI 502's? How can I ensure the vendor I order the part from is giving me the right one?

Sorry, but the reason for the stupid question is because the marine shop who did all the work on my new engines has no more of a clue than the man on the moon about these things. If it wasn't for a good friend and some great advice from OSO, the boat would still be in the shop. :(

If you have a Mercruiser distributor you should go to a Mercruiser dealer and have him look up the part number for the correct gear. If he is any good at all he should know what you are talking about.
Sincerely
Dennis Moore

Cord, how many hours ago did you install the Mark IV distributor? I'm curious. As I mentioned a buddy of mine put a Mark IV distributor from his old engines in some new Gen VI's with catastrophic results after about 65-70 hours of use.

I'm ordering 2 new gears today to install in mine, but I have 50 hours already and wondering if the damage has been done. Won't know until I pull the existing assembly to see if there's any wear.