Marine carb?

[clancy72]

The boat i recently bought has a 600cfm holley doublepumper carb. It is not a Marine Carb (Kaboom!). The boat runs very well with this carb, but i know it's unsafe... Any suggestions on easy maintenance hi-po carbs for marine us? I'm running a hi-performance 350, with an edelbrock hi-rise intake, edelbrock water jackets, edelbrock cam, pistons etc. (not sure of the specs or rpm range of the cam) all I know is that it was built specifically for marine use on this boat prior to my purchase...... It was mentioned to me by another forum reader that the engine was probably built to make it's max hp at 6500 rpm.... I know my out-drive won't handle anything of 5000... Help!

 

[John_S]

Re: Marine carb?

Outside of marine carbs, not aware of much being marketed from Edelbrock for marine engines. It sounds more like a car engine build then a boat. I'd check the ignition system, fuel lines, fuel pump, starter and alternator to make sure they are marine, too.

There are a number of 600-650cfm marine carbs. Most have vac secondaries. Holley might even have a marine double pumper. Before deciding on carb, I would try to get all the specs on how that engine was built and the specific part numbers. If this is a high-compression, long duration, single plane intake, aluminum head engine, it might be easier to start with a new engine.

 

[clancy72]

Re: Marine carb?

The ignition is an old dual point set up, Marine water pump, marine alternator, marine electric fuel pump,marine starter, brass plugs etc. it looks like a single plane intake. The engine has 400hrs on it and has never caused any problems for the previous owner. He is unable to get any info on the detailed specs as the builder passed away and his company closed. Due to the fact that it has made it 400 hrs without isssue, i'm thinking it must not be cammed too radically.. The only thing strange that he said was that the timing is advanced to 13 1/2 as opposed to the factory 9 (GM)..(won't run at factory specs) A new 8.1 HO is sounding more attractive all the time...

 

[John_S]

Re: Marine carb?

Dual point distributer- marine?

Well, if you are happy with its acceleration and top-speed and how the engine runs overall, just change out the carb. Not knowing your boat and drive, etc, would guess that the performance out of the hole to 2-3K rpms, might be lacking, especially with heavy load or skiing.

I am not a Holley guy, so don't know what the original builder went through in calibrating that carb. It does look like Holley has a marine 600 cfm double pumper: http://www.holley.com/0-80559.asp For a standard marine engine, I wouldn't advise it, but its as close a starting point to what you have now, as you are going to get.

 

[Scaaty]

Re: Marine carb?

Edelbrock Marine 600cfm carb on my 350...best carb out there...dump the car carb now..

 

[rodbolt]

Re: Marine carb?

about the only difference between the car carb casting and the marine version from holley was the marine version used J tubes for bowl venting and the auto stuff had straight tube. that and a marine UL and SAE and USCG rating.
to make it safe at least modify the vent tubes so in the event of a flooding situation the excess fuel gets dumbed down the carb and not all over the engine.
the other differences were usually in the power valves and the secondary air valve springs.
modifying the vents wont make your carb marine rated but it will make it safer in an engine box.