Distributer cap

butlp

Petty Officer 1st Class
Joined
Feb 26, 2002
Messages
302
Are marine distributer cap and rotors different from auto parts?<br />I purchased an auto cap and compared it to my Volvo Penta 4.3 GS part and it looked exactly the same.<br /><br />Is it the distributor that has the marine modification or the cap?
 

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: Distributer cap

here we go again(see the park plug wire post)i would say that a marine cap will have brass posts and resist corrision better<br /><br />i dont find that changeing a part like this every 2 to 3 years is that much money to not just buy the best oem marine part i can get<br /><br />tommays
 

liner85

Seaman Apprentice
Joined
Aug 23, 2004
Messages
32
Re: Distributer cap

I think marine distributors generally have a mechanical timing advance optimized for marine use, whereas an equivalent automotive distributor generally has a vacuum advance. Cap and rotors are generally, safely interchangeable (I use automotive), but as mentioned above, marine-specific parts may be better suited.
 

Ralph 123

Captain
Joined
Jun 24, 2003
Messages
3,983
Re: Distributer cap

From Dennis Moore, "Small Block Chevy Marine Performance"<br /><br />In an auto, if gas vapors leak from the fuel system, being heavier than air, they will escape out of the bottom of the engine and not usually cause much of a problem. Such is not the case with a boat. Gas and its vapors are very explosive. They will lie in the hull of a boat for quite some time, and any stray spark could ignite them - the boat could literally explode! All engine compartments are required by the USCG to be vented and connected to a blower motor that should be run to purge these gases before the engine is started. <br /><br />The electrical system in a boat need to be shielded to prevent sparks. The distributor cannot be made airtight because of the build-up of ionic gases caused by the spark jumping from the rotor to the distributor cap. It has to be vented. Sparks cannot go around corners, so an elbow or series of screens are used to vent the distributor but not allow any stray sparks to escape. The alternator and starter have brushes running on an armature that causes sparks. They are also made with devices, usually some sort of screen or a seal that is in the path of stray sparks..."<br /><br />
Have a Blast<br />By Pete McDonald<br />September 2002<br /><br />Don't skimp on maintenance.<br /><br />Almost immediately after taking on 90 gallons of gasoline, a 35' Chris-Craft exploded. The operator was thrown clear across the fuel dock, and his wife and dog were catapulted into the water. Pieces of the boat flew 250 feet. The resulting fire burned the boat down to the chines. Luckily, nobody was killed, but the blame for this disaster fell squarely on the owner. Why? Shoddy maintenance. <br /><br />"When you go the cheapest route possible, this is what happens," says Joel Fuoco of the Nassau County Marine Bureau in Long Island, New York, the investigator on the case. Fuoco listed three things he alleges the owner, a do-it-yourselfer, did wrong. <br /><br />When he replaced the fuel fill and fittings on his boat, he used galvanized pipe from a hardware store and didn't double clamp it. Dissimilar metals were touching, causing corrosion on both the fill and the tank. <br /><br />The owner replaced the fill but not the hose. The fuel hose had wear, so fumes penetrated it and filtered into the bilge. Only one of his four blowers worked, so when he flipped them on, the fumes weren't evacuated. <br /><br />The worst offense: Installing an automotive starter motor. Unlike marine starters, automotive starters are not spark protected—there are no seals to protect the inner workings from collecting gas fumes. In this case, the fumes seeped right into the casing. When he tried to start up after fueling, the spark from his ignition lit the fumes in the ignition casing and—boom!—a 35' boat was reduced to rubble. <br />The funny thing is, prior to the explosion, the boat didn't appear to be a junkyard dog. The hull was in prime condition, with high-quality fit and finish. By all accounts, it was a beautiful vessel. The owner spent a lot of money making it look nice but, when it came to the boat's vital mechanical systems…. <br /><br />It's amazing that people will spend tens—if not hundreds—of thousands of dollars on a boat and then nickel-and-dime the maintenance. Because a boat's systems are often exposed to harsh elements, the more you boat, the more maintenance it needs. That's why it's so tempting to find some inexpensive parts to fill in the gaps. But when you're dealing with mechanical and electrical systems, get the good stuff. When replacing wiring, use high-grade tinned-copper wire. For diesel engines, use high-pressure braided hoses; for gas engines, use A1 rubber hoses. Double clamp everything with stainless-steel clamps. Use stainless-steel or chromed-bronze fittings. (Some of the new plastic fittings work just as well, too.) And above all else, stay out of the auto parts store. <br />
 

butlp

Petty Officer 1st Class
Joined
Feb 26, 2002
Messages
302
Re: Distributer cap

The auto cap & rotor I bought had brass posts and rotor tip. It looked exactly the same as the old cap & rotor which I assume was an OEM Volvo part.<br /><br />Should there be spark arresting vents in the cap or are they built into the distributor housing?
 

liner85

Seaman Apprentice
Joined
Aug 23, 2004
Messages
32
Re: Distributer cap

Ralph makes a good point, but I don't think it applies to the cap and rotor. There is no safety issue that I'm aware of to using an automotive cap and rotor, other than durability perhaps.
 

tryan

Seaman
Joined
May 29, 2004
Messages
59
Re: Distributer cap

to answer lost canadians question, yes the caps and dizzy itself are different.<br /><br />on the cap, terminal construction will be brass AND a marine cap will have a seal at the base. an automotive one will not. boom. <br /><br />on the distributor, the housing will be vented by a screen on a marine distributor.
 
Top