I am considering doing a carb upgrade and I have 1 800cfm holley that I ran a few seasons in a baja I had but it is not a "marine" carb.

i had no issues with using this carb. I am just wondering if there are any real differences or benefits to a marine carb besides the J tubes.

It would be a hell of alot cheaper to buy another std 800 holley than to buy a marine 800.

Thoughts? Opinions?

i believe the throttle shafts are specific to a marine carb. pretty sure they are sealed unlike an automotive holley.

we have a local holley expert / carb guru (builds pro stock and off shore stuff for the big boys) and he told me to buy a holley hp and he would convert it to a "marine" setup. that included the j tubes and the sealed shafts.

good luck with your project.

Boooom !!!!! Plus they are not USCG approved. Not a good idea, same goes for alternator, starter, distributor....

Matters to your insurance company if you burn it down.

What is so different as far as risk of fire goes? I mean, you surely would want your car to catch on fire...so why would they not be the same?

I am just trying to understand the actual differences.

If I remember correctly.......the reason for the difference is that on a boat the fumes are contained in the bilge and in a car the engine compartment is more ventilated. Also with a boat you will see bigger impacts then a car. (ie. waves and such)

The idea of a marine carb is to keep any flooded fuel in the engine and to not alow it to pour on to the intake.

Gasoline fumes collect in the bottom of a boat bilge. They sit there and have to be removed by running blowers or via airflow once the boat is up to speed.

Gasoline fumes fall right out the bottom of a car where they dissipate and pose no explosion hazard.

Car carb will run fine on a boat.
Won't be legal if USCG inspects you, and will void insurance coverage for any loss if the insurance company inspects for it (and it doesn't have to burn up, it can sink, etc and still get denied coverage).

There, you now have enough information to make your own decision. Lots of car carbs on boats out there. Just want to make sure you understand what's at risk and then you are free to decide however you wish.

MC

Well....what I am gathering is that there really is not a huge difference besides in the pricing.

Yes, I understand needing to be USCG compliant. What I am saying is that for the minimal changes made to the carburetor by the manufacturer there is no real justification for the pricing.

What makes a holley marine so very much different, 2 tubes and a couple seals that sound like they should be there anyway?

Just the fact that it is for a boat makes it more money....

If you paid for the application cost and testing regimen required to get a legitimate USCG stamp of approval on a product, you would want to make up the cost in a reasonable amount of time. Given the actual sales volume of these marine carbs (each carb series has to get its own stamp), the cost increase charged is probably not as large as you want to make it out to be.

Unless you're new to boating, you already know that EVERYTHING with "boat" stamped on it costs more. Carbs are no different, but a lot of that cost goes towards the amortized cost of USCG certification. My honest guess is that SOME of the marine carbs offered haven't sold in high enough quantities to cover that cost yet. Of course, then there are the ones that have been sold in huge numbers through the years that offset the low volume ones.

Anyhow, yes, you can put J-Tubes on any carb, you can machine the throttle shafts for the correct seals, you can upsize the metering circuits, and you can drill and install a fitting for the fuel pump diaphragm vent hose, you can rejet and put the correct powervalves in for your application and you can then pretty much have a functional copy of a marine carb. The J-tubes, however, will change the jetting across the board, especially at cruise, so don't just cram them in and neglect to rejet.

MC