Exactly what makes a marine carb a marine carb?
Do all of you guys run a true marine carb?
It seems when looking at new carbs the choices are quite limited on "marine" carbs.

9999 times out of a ten thousand there is no difference. When there is it called kabbom! I will let other elaborate on the real differences but that is your main concern. Choices are limited but CFM and design choices are sufficient. Primarily, differences deal with how a malfunctioning fuel pump is handled, J tubes and throttle plates.

The main differences are the J style bowl vent tubes which direct fuel into the throttle bore if a float sticks and sealed throttle shafts which will not leak fuel onto the manifold.

Ron

That be right, rjcard!! "J" tubes are the marine thing and since we can all welcome Dennis Moore into discussion here; Just buy the book and it will all be clear!! --- Jer

Unfortunately, there is nothing similar between car and marine components in general in "most" cases, ESPECIALLY when it comes to fuel and spark curves, which ultimately tie your package together, and not only does it cost more for specific marine components, but usually is money well spent. All of the air bleeds, fuel transfer circuits, emulisification of the air and fuel, power valve enrichment, and the crutial timing of all these events are day and night different. Boats are always under a load, so the timing of power circuits, cruise circuits, transition between these circuits, fuel use, resulting oil contamination, WOT performance, spark advance, available voltage in the ignition secondary circuit, and many others are why so many guys are constantly pounding their heads on the wall, searching for remedys that will never happen due to the laws of physics (another topic alltogether)... and I guarentee you, anyone with consistent problems starting hot or cold, reliability and driveability issues, or broken and melted parts are not being truthful if they are telling you all of their parts are engineered for marine use. What I do for a living is solve Bermuda triangle electrical problems, and working through imcompatability issues caused by mis-matching components... and as sad as it is, if you wanna go fast in a boat week after week with only normal maintence... you best step up to the plate. Like I tell them... you can spend it now... or pay me later.

Find Me is absolutely correct!!!

FindMe has some of the most knowledgeable posts going,he should write articles for Dennis M

I use normal carbs on marine engines.(have lots of big cfm's from hot rod days)
As I know only difference is the J type tubes

Besides the "J tubes" and the throttle shaft seals (USCG required), according to Dennis Moore the mid-range fuel curve is slightly different (richer).

The Marine Carb doesn't have [or blocked,staked,theaded plugs]vacuum connections. Doug