1993 7.4L Mercruiser / Bravo 1 (300 HP) 600 CFM or 750 CFM Carburetor

[FuelishBehavior]

I have a 1993 7.4L Mercruiser/Bravo 1 in my Crownline 225 CCR. The current carburetor on it is a Weber 4bbl. I would like to change the carburetor to the new Edelbrock marine carburetors model number 1409 or 1410. They are 600 cfm and 750 cfm respectively. Can anyone tell me which one to use on my engine? By all calculations, 454 cubic inches at 4600 maximum rpm's at wide open throttle, and at 85% volumetric efficiency, I'm looking at about 604 cfm requirements. I usually keep my engine between 2800 and 3500 rpms cruise and I'm always looking for more efficiency. What is the CFM rating on the stock Weber carburetor because I would like to just match that to avoid having to re-jet/re-meter the new carburetor? Thanks!

 

[TilliamWe]

Re: 1993 7.4L Mercruiser / Bravo 1 (300 HP) 600 CFM or 750 CFM Carburetor

I do not know tha answers to your questions, but I am sure someone does. I will ask this, is there a 650cfm available? That would be the way to go. 750 is probably uneccessary.

 

[FuelishBehavior]

Re: 1993 7.4L Mercruiser / Bravo 1 (300 HP) 600 CFM or 750 CFM Carburetor

Edelbrock only offers a 600 cfm and a 750 cfm in marine configuration. They are supposed to be a direct replacement for the Weber Y43 carburetor on my engine. I'm just curious at which one I would have. The calculations support a 600 cfm but I've run 750's on the automotive version of the 454 with no issues. I'm interested in squeezing out another 1/4 mile to the gallon if it's possible.

 

[achris]

Re: 1993 7.4L Mercruiser / Bravo 1 (300 HP) 600 CFM or 750 CFM Carburetor

The current Weber carb is a 750cfm.

Putting a carb too big on would affect idle quality and low end torque. Carb too small will effect top end power.

The only way to reduce fuel consumption is the reduce the HMI input (less right hand)....

Chris....

 

[FuelishBehavior]

Re: 1993 7.4L Mercruiser / Bravo 1 (300 HP) 600 CFM or 750 CFM Carburetor

Thanks Chris, then I'll buy the 1410. I figured it was a 750 as well. And reducing HMI input is like quitting smoking.... one of the hardest things to do in life.

 

[Bondo]

Re: 1993 7.4L Mercruiser / Bravo 1 (300 HP) 600 CFM or 750 CFM Carburetor

Thanks Chris, then I'll buy the 1410. I figured it was a 750 as well. And reducing HMI input is like quitting smoking.... one of the hardest things to do in life.

Ayuh,... The 1410 is a carbon copy of yer Weber,...

All the parts interchange...

The 1409 is the carbon copy of the Weber used on the 4.3ls, 'n 350s,... the 650cfm model...