350 Economy EFI vs 2bbl

[SeattleMatt]

Hello, I recently repowered my 305 to a 350. Fuel prices are killing me and I was wondering how much of a difference EFI would make on this engine vs the 2bbl rochester I swapped over from the 305.<br /><br />I found a used EFI system which looks like it includes only the intake and runner and injectors for $450 at a used marine parts shop. It was labelled "not complete". I'm wondering if it would be worth the investment to try the conversion.

 

[QC]

Re: 350 Economy EFI vs 2bbl

Two ways to look at it IMO.<br /><br />1) EFI is cool, and if right, usually starts easier and also compensates for altitude. Maybe it makes a 10% difference in fuel, probably less than 5%.<br /><br />2) So lets be optimistic and go with the 10%. If you burn 50 gallons a weekend and you paid $3 a gallon, you would save $15. Should only take you 30 weekends to start seeing a savings. For me that would be more than three years . . .

 

[SeattleMatt]

Re: 350 Economy EFI vs 2bbl

hmm, doesn't sound like much of a savings then... i guess the 2bbl is less efficient than a 4bbl as well, so i'm really sol.<br /><br />40g tank can dissapear pretty easily in a day

 

[SeattleMatt]

Re: 350 Economy EFI vs 2bbl

guess i won't be making it to the san juans much uless i trailer it then

 

[QC]

Re: 350 Economy EFI vs 2bbl

I bet if you set that thing at 3500 RPM for a cruise that it would get at least 3 MPG, assuming that it is running right. That should get you 80 miles with 13 gallons in reserve. There is fuel on the San Juans too, right?<br /><br />Do you have a GPS? Do a trial run of about 10 miles, and top it off. See what you get. The best fuel economy (other than idle speed) is between 3000 and 3500 RPM. This goes for almost every test I have seen for an I/O and a V hull.

 

[SeattleMatt]

Re: 350 Economy EFI vs 2bbl

okay, thanks, I am putting a 23P on it next time it goes in, this should help too over the existing 21p

 

[QC]

Re: 350 Economy EFI vs 2bbl

What is your WOT RPM now with the 21P?

 

[SeattleMatt]

Re: 350 Economy EFI vs 2bbl

about 5300

 

[QC]

Re: 350 Economy EFI vs 2bbl

If that tach is right then absolutely you need the 23P. What was your WOT with the 305?

 

[SeattleMatt]

Re: 350 Economy EFI vs 2bbl

don't know the 305 was pretty much toast when I got the boat. I will say that it had a 17p on it and the original owner claimed excess of 50mph, which had to be a total lie, unless he was somwhere in the 8000rpm range on the 305, LOL<br /><br />the boat also came with a 19p which i used 4 a while.<br /><br />I would guess that the tach is off a bit, but I already have the 23p so I will be putting it on to try it. With it, i would guess I am going to be getting pretty close to the 50mph he was talking about

 

[QC]

Re: 350 Economy EFI vs 2bbl

The tach should be dead nuts on. Check to see if there is a switch in the back for 4, 6 or 8 cyl. Yours might be on the 6 cyl. setting.

 

[SeattleMatt]

Re: 350 Economy EFI vs 2bbl

ahh, will do