Convert mercruiser 5.7 4BBL to 2BBL

[JUANKI]

Hello


I have 2 engine mercruiser 5.7 V8 (1990) with carburetor rochester 4BBL in my boat, I need intake manifold or adapter carburetor for install carburetor rochester 2BBl and carburetor Rochester 2BBL for this engine, Where I can buy this part???

Best regards

 

[Don S]

Re: Convert mercruiser 5.7 4BBL to 2BBL

ebay would be a good start if you are looking for used.

 

[Scottdock]

Re: Convert mercruiser 5.7 4BBL to 2BBL

I recently did the same conversion and purchased the adapter plate from Whites Racing in Chicago. It was only $20 with free shipping.

Scott

 

[Bondo]

Re: Convert mercruiser 5.7 4BBL to 2BBL

Ayuh,....

If you're looking for Fuel Economy,..??....

You're Not going to find it That way....

As much as I dislike Rottenchester Quads,...
As long as it's in Good Repair,+ you keep out of the 2ndaries,...

It'll yeild Much Better fuel Economy than a 2bbl. Carb.....

and purchased the adapter plate

Especially That Way......

 

[JUANKI]

Re: Convert mercruiser 5.7 4BBL to 2BBL

Ayuh,....

If you're looking for Fuel Economy,..??....

QUOTE]

Yes I want to fuel economy, I?m from Spain and here the fuel is very expensive

 

[JUANKI]

Re: Convert mercruiser 5.7 4BBL to 2BBL

I recently did the same conversion and purchased the adapter plate from Whites Racing in Chicago. It was only $20 with free shipping.

Scott

You can tell me the web for I buy the adapter

 

[Bondo]

Re: Convert mercruiser 5.7 4BBL to 2BBL

Ayuh,...

What part of,"Your Fuel Economy will go Down", didn't you understand,..??

 

[JUANKI]

Re: Convert mercruiser 5.7 4BBL to 2BBL

Ayuh,...

What part of,"Your Fuel Economy will go Down", didn't you understand,..??

Sorry I not understand the question, I explain better the situation, My ship is a Delfos 36ft is very large and heavy other friends with ships very seemed and the same engines its engine had intake and rochester 4BBL in this moment they have installed intake manifold and carburetor Rochester 2BBL, these pieces were bought of old engines and they have reduced the consumption of fuel.

therefore I wanted to do that modification in my ship to test if I can lower the consumption

 

[JUANKI]

Re: Convert mercruiser 5.7 4BBL to 2BBL

for example this kit is valid?

http://www.jegs.com/i/Mr.+Gasket/720/1933/10002/-1

 

[JUANKI]

Re: Convert mercruiser 5.7 4BBL to 2BBL

Ayuh,...

What part of,"Your Fuel Economy will go Down", didn't you understand,..??

Sorry I not understand the question, I explain better the situation, My ship is a Delfos 36ft is very large and heavy other friends with ships very seemed and the same engines its engine had intake and rochester 4BBL in this moment they have installed intake manifold and carburetor Rochester 2BBL, these pieces were bought of old engines and they have reduced the consumption of fuel.

therefore I wanted to do that modification in my ship to test if I can lower the consumption

 

[Maclin]

Re: Convert mercruiser 5.7 4BBL to 2BBL

I would adjust the secondary opening rate on the Rochester carbs first, that is free. You can tighten up the spring that controls how soon and fast that they open and limit the cfm that way. Then limit the throttle travel manually with the controls too. All of that is free.

Most experience better economy with the Rochester spread-bore type 4bbl carbs than with a 2bbl. And you keep the "extra" power available if you need it later.

You may want to make sure all components are in tune on your engines, that the carbs do not leak fuel and are in good condition. It would be a shame if an expensive 2bbl conversion is put in when a rebuild and subsequent tuning of the original carbs would actually save fuel.