Mercruiser 305 carb

[waltsouza]

My carburetor is the last thing to update on my 1973 Tolly 26, the engine was

changed out to a Chevy 305 with a 1-1 velvet drive when We bought it.

It currently has a 4 BARREL ROCHESTER QUADRAJET. Has anyone changed their carb out and what

did you use?

Thanks!

Walt

[Brian Edmondson]

Hi Walt,

There are so many variables that come into play, that I think you need to be cautious about change.  I also run a small block Chevy (SBC), but mine started out as a 350.  The 305 can be built just as powerfully as the 350 by managing the variables.  The definitive information that you are looking for can be found in a book that has been out of print for a while.  I found it on Amazon two years ago and paid $210 for a paperback copy; but it is great information, it is detailed, and it is comprehensive.  I think I tried to get a copy through the King County Library system and wasn't successful.  Try that first.  If you also fail, either buy the book or come to my house and read it at my dining room table.

But, what I believe you have is a low-rise Chevrolet dual-plane spread-bore intake manifold designed for the Quadrajet.  If all we are talking about are those two variables, then stick with the Quadrajet as the best option.  There are MANY MANY other carb options... and you do not want to put a square-bore carb on a spread-bore intake manifold, so if you get away from the quadrajet you also have to do a new intake... and after having done that, you will likely have a less efficient engine... without analyzing other engine build variables.  I would rebuild your carb.  I used Orin's Carburetor Rebuild (Google that) at 4801 241st St SW, Mountlake Terrace, WA 98043.  Orin has been doing this forever and there is nothing he can't handle.  You have to call him.  Don't just head up there.  He came to me recommended by Bubba Backer at Fisheries Supply and I was glad to discover Orin as I went with Engine Quest IMCA aftermarket heads, which is where a LOT of my torque is coming from; and for a boat you don't care about HP, you want torque.  Vortec engines produce HP and are great for cars.  Quench Effect engines with great flow in the heads produce torque.

BE

[Brian Edmondson]

OOPS... I DID IT AGAIN... The book is "Small Block Chevy Marine Performance" by Dennis Moore.