Carb questions on 5.0 to 5.7 swap.

[RCSConstruction]

Hello and good morning everyone.
I have been looking for info on what I need to do in order to get the right carb/settings for my motor.
Does the 5.7 gl have a 4 bbl or a 2bbl carb?
I know a 5.7 will run with my current 2bbl but not sure if i need to up the jet sizes or will it adjust with the air/fuel mixture screws?
Will my volvo manual show me the difference?(still hasn't shown up) Think I can just get a 5.7l carb kit and install those parts?
Or should I just break down and buy a holley/eldebrock 600cfm marine carb and call it a day?
Thank you

 

[Bondo]

Re: Carb questions on 5.0 to 5.7 swap.

Whether you go thru your 2bbl, or Buy a 4bbl.Carb,+ Manifold is entirely up to You,...........

The 2bbl.,..... I'd just bolt on,+ Run it to See what it Needs.......
You motor,+ it's Sparkplugs will Tell you what Needs doing.........

If you go with a 4bbl. replacement,........ I personally prefer the Edlebrock Preformer series,......
It's a copy of the old Carter AFB,..........
With a Tuning Kit,..... It'll make about Anything run Right......


Btw,......... A 4bbl. is only Good for an Extra 25/35hp...............

 

[bjcsc]

Re: Carb questions on 5.0 to 5.7 swap.

The 5.7GL has a 2bbl, the 5.7GS has a 4bbl.. I don't know if they changed through the years or not (but someone here probably does), but for the LK series engines (1997) they were as follows:

5.7GL: Holley List#80402-1 500CFM Model 2300-2V
5.7GS: Holley List#80390 650CFM 4175 Spread Bore

 

[RCSConstruction]

Re: Carb questions on 5.0 to 5.7 swap.

Thanks for the replies.
This manifold volvo-penta part# 3856270 is a 4bbl intake. The carb had an adapter plate under it.
So...I am thinking the edelbrock too. I started to use the carters/eldebrocks on my "project" motors after screwing with a holley one too many times. Their secondaries are a better design than holley and the two piece body is a better design. Of course these are just my opinions.
I only have one concern and that would be fuel mileage and excess HP. Will a volvo sx-m hold up to 300hp? Also the 2bbl holleys have always been very reliable carbs, with descent performance IMO.
Thanks again

 

[RCSConstruction]

Re: Carb questions on 5.0 to 5.7 swap.

The 5.7GL has a 2bbl, the 5.7GS has a 4bbl.. I don't know if they changed through the years or not (but someone here probably does), but for the LK series engines (1997) they were as follows:

5.7GL: Holley List#80402-1 500CFM Model 2300-2V
5.7GS: Holley List#80390 650CFM 4175 Spread Bore

You know that HP rating between the 2bbl and the 4bbl?
Thanks for the detailed info.

Edit--
So the L=limited 2bbl and the S=superior 4bbl?

 

[John_S]

Re: Carb questions on 5.0 to 5.7 swap.

Probably around 250/260hp for 2brl and 280/290hp for 4brl. The 4brl manifiold doesn't flow as much as the mpi. That is assuming you have a stock marine cam in your new longblock.

I believe the volvo sx drives can handle more than the merc alphas, which are ok to 300hp. Go see what the largest engine that volvo mates to it.

I'd go with the 4brl.

 

[Bondo]

Re: Carb questions on 5.0 to 5.7 swap.

The Fuel Mileage will be determined by Your Right Hand.........Actually,.. The HP,+ related Abuse as Well.......

The Small AFB is of a spread-bore design, in that the primaries are Smaller than the 2ndaries........ The 750cfm 1 is a Square-bore.....

The Merc./Weber on My 4.3LX is the Exact Same Carb.... I Love it,......

My fishing grounds are very close to My riverhouse, so idling out,+ getting set up for the troll is about the Right Timing, so My boating is usually Very Slow,......
I sometimes Think that My motor is Making Gas,..... Weeks on a Tank......
But,............
If I want to go out,+ Abuse a Waterskier with My torque-Shift Prop,.......
She'll Suck the Fuel, like an Irishman at a Free Beer Party............

 

[Scaaty]

Re: Carb questions on 5.0 to 5.7 swap.

I personally prefer the Edlebrock Preformer series,......
It's a copy of the old Carter AFB,..........
With a Tuning Kit,..... It'll make about Anything run Right........

Yep, yep, yep...600cfm...tossed my Q-Junk, aint looked back there yet​

 

[RCSConstruction]

Re: Carb questions on 5.0 to 5.7 swap.

Ordered up the 600cfm marine series.
This motor is now identical to the one I had in my 73 blazer.
Thanks all

 

[Tail_Gunner]

Re: Carb questions on 5.0 to 5.7 swap.

The Fuel Mileage will be determined by Your Right Hand.........Actually,.. The HP,+ related Abuse as Well.......

The Small AFB is of a spread-bore design, in that the primaries are Smaller than the 2ndaries........ The 750cfm 1 is a Square-bore.....

The Merc./Weber on My 4.3LX is the Exact Same Carb.... I Love it,......

My fishing grounds are very close to My riverhouse, so idling out,+ getting set up for the troll is about the Right Timing, so My boating is usually Very Slow,......
I sometimes Think that My motor is Making Gas,..... Weeks on a Tank......
But,............
If I want to go out,+ Abuse a Waterskier with My torque-Shift Prop,.......
She'll Suck the Fuel, like an Irishman at a Free Beer Party............

Bondo Rc has the same boat i have, my boat is a 4.3 tbi 225 hp. I can turn a 20 p 4 blade to 4900 rpm@55 mph with a 400lb load and a full tank of gas, now hes has a 350, would he be able to turn the same prop but in a 22 pitch 4 blade to the engine's full potential, the 4.3 can only turn it to 4400 rpm, any thought's here?

 

[John_S]

Re: Carb questions on 5.0 to 5.7 swap.

Besides engine rpms on same boat, need to know if the drive gear ratios are the same or not. The 350 in an 18' boat will test the hull for its high speed handling ability.

 

[Bondo]

Re: Carb questions on 5.0 to 5.7 swap.

Ayuh,........

As you might know,..... I'm Not a Volvo Guy,... I Don't Know What they use for Ratios in their drives,.....

Mercruiser uses a lower ratio in the 4.3l drives,.... Mine is a 1.65:1.....Where as the V8s use about 1.5:1....

 

[RCSConstruction]

Re: Carb questions on 5.0 to 5.7 swap.

It's a SX-M (wondering what M means) at 1.60 with 4800 rpm for both the 5.0 and 5.7l engines.
I also noticed that the 5.7gs has a 1.53 and the SX-M was installed behind the 7.4l gs at 1.43
I guess this drive will be able to handle the hp.
Thanks

 

[John_S]

Re: Carb questions on 5.0 to 5.7 swap.

What pitch prop did you have on the 5.0 to get 4800? If you were already up in the 23" pitch range, your choice of props to work with the new 5.7L, may be limited. Worse case, is a gear change in the drive, to get back in a reasonable range.

http://www.go-fast.com/Prop_Slip_Calculator.htm

 

[RCSConstruction]

Re: Carb questions on 5.0 to 5.7 swap.

What pitch prop did you have on the 5.0 to get 4800? If you were already up in the 23" pitch range, your choice of props to work with the new 5.7L, may be limited. Worse case, is a gear change in the drive, to get back in a reasonable range.

http://www.go-fast.com/Prop_Slip_Calculator.htm

I have no idea what the pitch is on my current prop.(its all banged up too) I imagine it is stock.
I took these figures out of my Volvo manual????

 

[John_S]

Re: Carb questions on 5.0 to 5.7 swap.

"I took these figures out of my Volvo manual????"

Those numbers are for the WOT rpm with whatever load you boat with. You adjust to that by changing your prop pitch. You will need to baseline after the install, debug, and break-in, phases. Not sure on volvos, but the prop size and pitch are on the inside of hub of many props. Plan on working with a prop shop or spending time/money for some initial trial and error testing.

 

[RCSConstruction]

Re: Carb questions on 5.0 to 5.7 swap.

I took at look at the prop. (thanks for the info) and found it to be 14 1/2 x 19.

 

[Bondo]

Re: Carb questions on 5.0 to 5.7 swap.

Ayuh,.........
You're going to be into the 23" range with All that Raw HorsePower you're puttin in there.......

 

[jimmbo]

Re: Carb questions on 5.0 to 5.7 swap.

Did that swap 2 or 3 yrs ago. Took the Holley 500 cfm 2bbl off and put in its place a Holley Marine 650 spreadbore. My 2002 VP 5,7 came with a real nice 4bbl manifold and adapter plate to mount the 2bbl. Out of the box it gave me about 350 rpm more which with the gear my out drive has was about 225rpm. I was able to add 2 more inches of prop to bring my rpms down. Top end went from 59 mph to 64-65 mph. Small primaries prevented loss of bottom end torque

 

[John_S]

Re: Carb questions on 5.0 to 5.7 swap.

Jimmbo,

Did you do just a 2brl to 4brl swap or did you also upgrade from a 5.0 to 5.7L? RCS is doing both, and think he will going more than 2" of pitch.