2 Barrel VS. 4 Barrel Opinions

[odie241]

Hi everyone,Hope you guys and gals had a nice boating weekend.I am looking for opinions.I have a 1977 Thompson with a 400ci chevy with a pre alpha drive.Now that thats out of the way,I currently have a 4 Barrel carb on the boat,and I really dont like the gas milege i am currently getting.

I have a chance to pick up a 2 Barrel carb and intake from my local marine store for a decent price.What are the pro's and cons on this switch.

I know on a car,the 2 barrel has exellent power out of the hole,is that going to be the same on the boat?I am just looking for better fuel consuption.If i lose a few MPH that would be fine.We just cruise mostly,with an occasional weekend of ski'ing or tubing,and alot of sitting on the sandbar swimming.Any and all opinons are welcome,Thanks For your time,,,,Odie

 

[zbnutcase]

Re: 2 Barrel VS. 4 Barrel Opinions

As hard as marine engines work, I doubt it would be worth the effort.

 

[HT32BSX115]

Re: 2 Barrel VS. 4 Barrel Opinions

Howdy,


Changing the carb on a boat won't really affect your fuel consumption much unless your engine is WAY under-carbed....

Your fuel consumption is really more directly related to your right arm!


Regards,


Ric

 

[MTribe08]

Re: 2 Barrel VS. 4 Barrel Opinions

Hi everyone,Hope you guys and gals had a nice boating weekend.I am looking for opinions.I have a 1977 Thompson with a 400ci chevy with a pre alpha drive.Now that thats out of the way,I currently have a 4 Barrel carb on the boat,and I really dont like the gas milege i am currently getting.

I have a chance to pick up a 2 Barrel carb and intake from my local marine store for a decent price.What are the pro's and cons on this switch.

I know on a car,the 2 barrel has exellent power out of the hole,is that going to be the same on the boat?I am just looking for better fuel consuption.If i lose a few MPH that would be fine.We just cruise mostly,with an occasional weekend of ski'ing or tubing,and alot of sitting on the sandbar swimming.Any and all opinons are welcome,Thanks For your time,,,,Odie

I don't think you will notice much change in your fuel consumption at all. Essentially, a 4 barrel carb is only a 2 barrel carb UNTIL you hammer it to the floor, which it sounds like you don't do much of at all anyway.

I have a 5.7 with a 4 barrel and I bet I can count on 3 fingers the amount of times I've been in the secondaries.

Is your intake set up for a 4 barrel right now, or will you have to buy that too?

 

[odie241]

Re: 2 Barrel VS. 4 Barrel Opinions

I don't think you will notice much change in your fuel consumption at all. Essentially, a 4 barrel carb is only a 2 barrel carb UNTIL you hammer it to the floor, which it sounds like you don't do much of at all anyway.

I have a 5.7 with a 4 barrel and I bet I can count on 3 fingers the amount of times I've been in the secondaries.

Is your intake set up for a 4 barrel right now, or will you have to buy that too?

Heres the intake and carb that are on there now

its a 4 barrel Edelbrock carb,with a 4 Barrel Edelbrock intake.I am sure I can get a adapter plate to go to a 2 Barrel,but with the few replys i got,I see that its not going to change the fuel consuption much

 

[John_S]

Re: 2 Barrel VS. 4 Barrel Opinions

Looks like an auto carb sitting on top of a single plane intake. If so, get rid of both. I wouldn't go with a 2brl for the replacement though.

 

[Bifflefan]

Re: 2 Barrel VS. 4 Barrel Opinions

Diffenitly loose the single plane intake. That is killing you. It doesnt even start to work until 1500 and not even that well till you higher than that. Your are wasting fuel from poor atomization.
If your into speed (and you said you werent) get a bow tie intake. Its a little better than a normal stocker and has torque from idle up.

Id think a good Marine 4bbl and a dual plane intake should help, will probably get better mileage and more power when you need it.

That is assuming you dont have some hot rod cam for a car in it.

 

[jtmarten]

Re: 2 Barrel VS. 4 Barrel Opinions

A good dual plane will help alot, they make power from 1500 up.
I'd get rid of the hose stubs and get some caps for the vac ports.
Once you put the 2V on, you'll be wishing for more power!
If you setup a 4V right, you can cruise all day long on the primaries, and only get into the secondaries when you push it. Generally the primaries on a 4V will be smaller than the primaries on a 2V, assuming you'll be running a 600cfm on the 400, so you'll be more fuel-efficient too.

 

[achris]

Re: 2 Barrel VS. 4 Barrel Opinions

Interesting... Nobody else seems to have noticed the '898' on the rocker cover. That engine was originally supplied with a 2bbl carb (either a MerCarb or a Rochester).

I also notice that the carb appears to be an automotive unit. You really should bin it and put a proper marine unit on.

Chris.........

 

[Bifflefan]

Re: 2 Barrel VS. 4 Barrel Opinions

A good dual plane will help alot, they make power from 1500 up.

A dual will make power from idle to about 5500.

 

[odie241]

Re: 2 Barrel VS. 4 Barrel Opinions

Thanks Everyone for your honest opinions.This is how the boat was when i purchased it a few months ago,I have changed a few things so far,like added a flame arrestor,marine starter,dual batterys,just bought an Isolator and a perko switch for the batterys.Anyone know a part number for the dual plane intake you guys are talking about.

The guy said it had a 305 mercrusier in it,that locked up from not winterizing it properly.So i am slowly putting everything back to where it should be.He did say the cam is the original one out of the 305,so it is a marine cam.

If it wouldnt be too much hassle,part numbers for the carb and intake would be great,I want the boat to be as safe as possible for me and my family and friends.

Thanks for all the help,,,,,,,,,,,Odie

 

[HT32BSX115]

Re: 2 Barrel VS. 4 Barrel Opinions

Thanks Everyone for your honest opinions.This is how the boat was when i purchased it a few months ago,I have changed a few things so far,like added a flame arrestor,marine starter,dual batterys,just bought an Isolator and a perko switch for the batterys.Anyone know a part number for the dual plane intake you guys are talking about.

Sounds like most everything on that engine is/was "automotive"

 

[achris]

Re: 2 Barrel VS. 4 Barrel Opinions

A standard 4bbl intake as supplied by Merc (-72646) and an Edelbrock 1409 carb would be the best set up you could get.

 

[John_S]

Re: 2 Barrel VS. 4 Barrel Opinions

A standard 4bbl intake as supplied by Merc (-72646) and an Edelbrock 1409 carb would be the best set up you could get.

If you can't find a cast-iron one, a Edelbrock or other quality alum dual plane intake should work fine. Being you are in IL, that is a long way from any saltwater.

 

[odie241]

Re: 2 Barrel VS. 4 Barrel Opinions

If you can't find a cast-iron one, a Edelbrock or other quality alum dual plane intake should work fine. Being you are in IL, that is a long way from any saltwater.

Yep,no saltwater here,all just fresh water.I lived in Florida for 14 years,and that salt water is terrible on boats.I found a Edelbrock dual plane on craigslist yesterday,went and bought it,guy cleaning his garage out,picked it up for $40.00 Now I just need to find a good cheap 4 Barrel Marine carb,Preferbly one that needs rebuilt.

 

[haulnazz15]

Re: 2 Barrel VS. 4 Barrel Opinions

Find an Edelbrock Performer intake for the 305, then get the Edelbrock 1409 Carb. You'll definitely be happy with that combo performance-wise and fuel mileage-wise.

Yes, the 898 was a 2bbl setup from the factory, but there's no reason not to go with a 4bbl if you are swapping stuff around.

 

[MTribe08]

Re: 2 Barrel VS. 4 Barrel Opinions

Yep,no saltwater here,all just fresh water.I lived in Florida for 14 years,and that salt water is terrible on boats.I found a Edelbrock dual plane on craigslist yesterday,went and bought it,guy cleaning his garage out,picked it up for $40.00 Now I just need to find a good cheap 4 Barrel Marine carb,Preferbly one that needs rebuilt.

Sweet! It would be great if you would report back how everything goes and the performance difference once you get dialed in.

 

[odie241]

Re: 2 Barrel VS. 4 Barrel Opinions

Sweet! It would be great if you would report back how everything goes and the performance difference once you get dialed in.

I surely will reply back with my progress,as soon as i find a carb,and have it redone by my friend,whos a master carb rebuilder,i will post some pictures,and the results

 

[SeanMcl]

Re: 2 Barrel VS. 4 Barrel Opinions

That 400 Chev is a lot of motor for an 18 foot Tri hull. Your friend should be able to set that carb up so the secondaries open about 3800 RPM fully loaded and you can cruise without ever touching them. With that motor, your cruise speed is going to faster than my WOT!

 

[sethjon]

Re: 2 Barrel VS. 4 Barrel Opinions

With a 2 bbl you will use more throttle to do the same type of cruising you are doing and in the end probaly won't save enough gas to make it worthwhile. Also, when you want a good hole shot you will probably be starved for more gas.