General Category > Quadrajet Carb Talk and Tips

Marine Carb rebuilds

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randy4140:
Cliff, from what I hear on here and "internet" you are the one with the q jet answers..
How about the marine carbs. I have twin GM 305's in my 29 ft CC Catalina. does have wedge plate under carb to somewhat level them out. No mods to engines, and are straight shaft inboards. 8000lbs. I would think that at around 3000 rpms I should only be on the primaries, and the fuel usage should be not bad with the twins, (that being said I know it is a boat and they like fuel) It seems like I am using a lot of fuel and have rebuilt the carbs, there was considerable debris in the bowls ect. They seem to run fine but am wondering what base settings I should be using for marine use. All your info in the book is pointed at automotive use. Can you help or is there somewhere else I should be looking. Thx in advance.

Ethan1:

--- Quote from: randy4140 on June 14, 2016, 10:35:36 AM ---Cliff, from what I hear on here and "internet" you are the one with the q jet answers..
How about the marine carbs. I have twin GM 305's in my 29 ft CC Catalina. does have wedge plate under carb to somewhat level them out. No mods to engines, and are straight shaft inboards. 8000lbs. I would think that at around 3000 rpms I should only be on the primaries, and the fuel usage should be not bad with the twins, (that being said I know it is a boat and they like fuel) It seems like I am using a lot of fuel and have rebuilt the carbs, there was considerable debris in the bowls ect. They seem to run fine but am wondering what base settings I should be using for marine use. All your info in the book is pointed at automotive use. Can you help or is there somewhere else I should be looking. Thx in advance.

--- End quote ---

 Welcome to CHP!

 What are the carburetor numbers stamped on the Quadrajet's? Should start out 704xxxx, 1705xxxx or 1708xxxx.

randy4140:
one of them is, 17080564, and below this # is 3174
the circle #s are17060303.
Sorry I should have included that info before in the post

randy4140:
Cliff, Ethan....Any ideas, on Base marine setting, or necessary adjustments, economy adjustments, Ethan wanted the carb #'s, which I replied
Any help is appreciated
Randy

Hillbillyenginering:
A few things you should understand about marine engines. The can grind on them are usually more aggressive than autos. The ability to cool the engine is much greater,because of all of the heat transfer to the surrounding water. So when you say "stock" it would probably have higher compression and aggressive cam. Look up the info on them and compare to what even a stock corvette would be.
I bet your stock rebuild would be on par with cliffs recipe #1.
If at all possible source two of the same model numbers.
Buy the rebuilds kits from cliff. Buy the upgraded super sckucuum one!

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