Crab type dist cap

[RichRab]

I have had my 2002 Sea Ray for about 10 years and never had a dist cap problem with anything before. I have tuned the boat using Mallory cap and rotor set and one example was last year when the boat shut off. Had an old cap and put it on and the boat started right up. Replaced it with a new cap and start of this season the boat started right up. Next day would not start but kept backfiring when cranking. New cap and it started right up and seems fine. All old caps look fine. Maybe there is a better brand? Thank you. RR

 

[achris]

Usually the OEM is the best option. Mallory are a very cheap aftermarket alternative. Like most things in life, you get what you pay for.

You don't mention what engine you're working on....

Chris........

 

[stonyloam]

Maybe there is a better brand? Thank you. RR

There is, OEM, I'm with Chris!

 

[RichRab]

I thought Mallory was a well known trusted name but will try OEM. 5.0 MPI Thanks RR

 

[achris]

I thought Mallory was a well known trusted name but will try OEM. 5.0 MPI Thanks RR

The important word in that line is 'was'.... Up until about the 80's they were the 'go to' supplier for OEM. But since then, the quality has dropped off dramatically... They now rate quite far below Sierra. Maybe they have moved their manufacturing facilities to a 'less labour costly' country? :noidea:

Chris.......

 

[alldodge]

Go to your local GM dealer and pick one up, may save some over the Merc dealer

 

[gm280]

Usually when a distributor cap goes bad, it starts to cross fire. And once that starts, carbon tracking take over and it stops working properly. If you could really look at the old caps that wouldn't work correctly anymore, you will fine little carbon track lines from one terminal to others. And cheaper designs and materials allow that to happen easier...

 

[RichRab]

Boat ran perfect then just shut off. Changed cap and it started. Cap was not old and looked fine. Used ohm meter and looked fine. Then problem this year again. New cap and starts right up. No carbon tracks. All looks fine. Thanks.

 

[RichRab]

So we have quicksilver, merc and Sierra. My guess is Merc should be the best quality. Any concerns using the other 2 brands?

 

[achris]

Quicksilver is the Mercury Marine accessories brand. Same dog, different name. Another one worth chasing is Delco (I believe they are the actual manufacturer they Merc buy from)... Try Summit -> http://www.summitracing.com/int/search/part-type/distributor-caps/cap-style/crab-style

Chris.......

 

[RichRab]

Does Sierra have anything to do with Merc? And shouldn't I use a marine part? Thanks. RR

 

[gm280]

Boat ran perfect then just shut off. Changed cap and it started. Cap was not old and looked fine. Used ohm meter and looked fine. Then problem this year again. New cap and starts right up. No carbon tracks. All looks fine. Thanks.

Rich, some times the material those cheaper caps are made from will carbon track inside the material also. So you could have a great looking cap, but have an extremely high resistive carbon track internally. And if you ohmed it out, it would appear open because of the extremely high carbon track. But once high voltage is present, it takes the path of least resistance and WALA, cross fire. A really good idea when changing caps is to also change to the same manufacturer's rotor as well. They were designed to work together. And even a few thousands air difference between different manufactures can mean firing and running good, or not. The rotor really doesn't touch any terminal but comes close and the high voltage spark jumps the air supposed to be very little air gap... Just some info to think about. So change them as a set and make sure the are from the same manufacturer. And remember the actual condition of the rotor has a heck of a lot to do with proper firing as well. :thumb: