Can I upgrade/convert a 2bbl V8 to a 4bbl?

[tmh]

I read something in another forum about changing a 2bbl engine to a 4bbl. Can this be done, and if so, what's the approx. cost to have someone do it for me ?(I'm not too good with repair stuff).

1985 305 v8 200hp Mercruiser with Alpha drive.

 

[Silvertip]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

Swap the intake manifold and carb. However, the 305 heads have pretty small valves and therefore don't flow as well as 350 heads. Any small improvement in performance may not be worth the cost. If you can't get more air through the engine it can't make more power. Power is a combination of displacement, cam, compression, and carburetion.

 

[bjcsc]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

Power is a combination of displacement, cam, compression, and carburetion.

And ignition advance.

You will find this will not be worth doing. My guess on the cost would be ~$2,000.

 

[whywhyzed]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

I found all the stuff used.. be patient....you can do it affordably... Whatever you budget, add $400 to 500 for a good used running 350 long block of the same vintage and swap it in too, reuse the 305's cam if it's good and switch to brass freeze plugs....
You can add 60 hp for around $1200 if you are thrifty.

What pitch prop are you running now?
If more than 17P now, you might have a drive ratio issue adding that much power....

edit - oops just read the "not handy" thing... I would expect labour to run another $600 to $1200

 

[bamadave]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

It would be one thing if you could do the work yourself, but to pay someone to try to get more power, your money might be better spent buying a boat with more power. My experience with basterdized boats is they are never the same after the work is done.

 

[tmh]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

OK, thanks. I'll cross that one off my "boat to-do" list! Actually, it never made the list because I just heard about the idea yesterday and you guys showed told me enough so i know I won't be doing it!

Thanks again!

 

[lilmandavis]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

take that 2000 and get a 350 long block .

 

[Cptkid570]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

Wait.. $2000 to switch from a 2bbl to a 4bbl? Wouldn't he really only need to buy a 4bbl carb and a 4bbl intake manifold? Those two don't = $2000.

 

[Silvertip]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

Cost per/hp gained and marginal increase in performance is a losing proposition. Remember, he can't do the work himself. If one wants to achieve any significant level of performance improvement from a 305, simply the best way to do it is swap it for a 350. Remember the cliche "There is no substitute for cubic inches".

 

[MelLandry]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

I believe the cliche is better stated, "There's no replacement for displacement."

 

[lilmandavis]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

yep! thats right mell!! not to beat the dead horse but that would be the most cost effective route in gaining any noticable difference in a 305. cause to go to a 4 bbl, he would have to install heads with bigger valves, a cam to open those valves and prbably push rods as well. that with the carb and manifold will well exceed 2k!!! cause with those small valves there really aint gonna chang with a 4 bbl unless its air inducted.

 

[calwldlif]

Re: Can I upgrade/convert a 2bbl V8 to a 4bbl?

I agree with Silver Tip
and Bj
8)