I need a new carb. Which one should I get for my Chevy 305?

[rs2k]

My old Rochester carb is worn out and has has a remote choke design and is on an intake that doesn't accept remote chokes. I really need to replace it before I take this boat to the ocean. I'm looking at either another Rochester or maybe a Holley or Edelbrock marine carburetor.

I have a 1981-ish Chevy 305 HO with 601 heads, a stock iron spread bore intake and an unknown cam (could be a truck cam or a marine cam). It is in a 3000 lbs boat with a top speed around 35 MPH with my 14 pitched prop hooked up to a stringer drive. If my tach is correct I cruise around 3000 RPMs at 25 MPH. I am planning on getting a 16 pitched prop in the near future.

I am unsure as to which carburetor I should get to replace my worn out Rochester. What are the differences between the 3 brands? I know I will either need a new intake or an adapter to make the square bore carbs fit, but that is OK. I'd rather put the better carb onto another intake than stick with the easy to do.

 

[mthieme]

Re: I need a new carb. Which one should I get for my Chevy 305?

I can compare the Holley and Rochester.
The Holley will give better performance and worse economy.
The Holley is finickier and harder to get adjusted properly.
Rochesters are more common as are the kits/parts.
It is also easier to find someone who knows a Rochester.
Do not expect too much by slapping on a performance carb without touching any of the other part of the breathing.

 

[achris]

Re: I need a new carb. Which one should I get for my Chevy 305?

Merc stopped using Holleys a lot of years ago... for a reason... Go with a straight replacement of what you have... The original has given you good service, so stick with it...

The Edelbrock is a Carter AFB knock-off... But a damn good carb... Weber also copied them, and that's what Merc use when they put a 4bbl on an engine...

Chris........

 

[rs2k]

Re: I need a new carb. Which one should I get for my Chevy 305?

I just rebuilt this engine and put the old carb back on it. I do not know how well this carb ran. I have been leaning towards an Edelbrock only because I bought a new one from Autozone 4 years ago and it worked pretty good on the tired 305 I had in my 81 Impala. I just don't know if mechanical secondaries will be OK for such a heavy boat.

 

[achris]

Re: I need a new carb. Which one should I get for my Chevy 305?

I just rebuilt this engine and put the old carb back on it. I do not know how well this carb ran. I have been leaning towards an Edelbrock only because I bought a new one from Autozone 4 years ago and it worked pretty good on the tired 305 I had in my 81 Impala. I just don't know if mechanical secondaries will be OK for such a heavy boat.

They work just fine.... As I said, Merc have been using them since about 1992...

 

[180shabah]

Re: I need a new carb. Which one should I get for my Chevy 305?

.....Edelbrock.....I just don't know if mechanical secondaries will be OK for such a heavy boat.

Yes the secondaries are mechanical, but there is a vacuum operated air door above them. You will never draw more from the secondaries than the engine can handle.

 

[MikDee]

Re: I need a new carb. Which one should I get for my Chevy 305?

I do believe on the Edelbrock/CarterAFB/Weber clones, besides the mechanical secondary's, there an air valve above them that's counterweighted (inside the carb), & operated by vacuum, a very simple efficient design, one of my favorite carb designs.

 

[Maclin]

Re: I need a new carb. Which one should I get for my Chevy 305?

I just rebuilt this engine and put the old carb back on it. I do not know how well this carb ran. I have been leaning towards an Edelbrock only because I bought a new one from Autozone 4 years ago and it worked pretty good on the tired 305 I had in my 81 Impala. I just don't know if mechanical secondaries will be OK for such a heavy boat.

On those carbs, as others have mentioned, even though the bottom plates open progressively with the throttle linkage, engine demand governs the secondary participation by way of the weighted airvalve at the top of the secondary barrels and is not considered a mechanical secondary carb. They work pretty smooth. No worries about using one on a boat or any other application.

 

[Maclin]

Re: I need a new carb. Which one should I get for my Chevy 305?

I need to qualify my statements, that if that type of carb is properly sized for the engine they work well and secondary operation is smooth. A grossly oversized Carter or Eddy will not perform well on any engine that is too small for it. The 600 cfm range seems to be best for the 300-350 ci displacements.

 

[Mkos1980]

Re: I need a new carb. Which one should I get for my Chevy 305?

My vote is for an Edelbrock 1409 600 CFM. I got one this year and its made a world of a differance. I love it. It worked great on my stock 350 and now with the mods. Idles the same and no hesitation or anything.

 

[achris]

Re: I need a new carb. Which one should I get for my Chevy 305?

My vote is for an Edelbrock 1409 600 CFM. I got one this year and its made a world of a differance. I love it. It worked great on my stock 350 and now with the mods. Idles the same and no hesitation or anything.

Identical to the Webers used by Merc for more than 10 years...

Chris........