5.7 2 barrel to 4
 

I have a 1996 2 barrel (210 HP) I want to change out the intake and Carb to a 4 barrel. What manifold and Carb combinations would you guys recommend?

Re: 5.7 2 barrel to 4
 

You would need to change as a minimum the camshaft as well to be able to see any real difference.

Re: 5.7 2 barrel to 4
 

That is not true.

The older (pre-Vortec) 2bbl's are super ineffecient. As rpms climb, things get worse. After 3500-3800rpm they really start to take a 'dump.'

A modern 4bbl intake is much better.

How your boat responds to extra power is a totally nother thing.

BTW: A cam would make more power, yes, but just swapping over to a good 4bbl carb and intake manifold will still add good power.

What type of boat and how much does it weigh ? Are we propped correctly already ?

Re: 5.7 2 barrel to 4
 

Im not sure what the throttle bracket looks like on that year, but on my 87' whihc used to be a 200hp 305 with a 2 barrel I had to weld up a new throttle cable bracket as the 2 barrel is not as wide as a 4, so the stock aluminum bracket wa suseless to me. Just a small detail often overlooked. I know I didnt think about it till I was bolting stuff on

Oh ya also had to play with the fuel lines as the inlet is not near the same location as the new carb

Re: 5.7 2 barrel to 4
 

heres a pic of my bracket

http://www.sbftech.com/bracket.jpg

Re: 5.7 2 barrel to 4
 

The 1996 2bbl 5.7 and the 1996 4bbl 5.7 used the same cam.

Dave

Re: 5.7 2 barrel to 4
 

Boomer

I took a Vortec 2 BL 5.7 and made the following changes
Trick Flow alum. heads
Edelbrock RPM air gap manifold
BG Demon carb set up by Nickerson Performance
Stainless Marine Exhaust Manifolds
FULL MSD Ignition

Original Cam

Made 10 MPH more.

It can set for a period of time (2) pumps on the throttle fires up and idles a 600 RPM, thats the difference between a Nickerson carb and an out of the box carb.

Forgot the 1.6 Rockers a tweak more cam.

Re: 5.7 2 barrel to 4
 

Thanks I know the internals are the same, and I was looking at an edlebrock( 2101 0r 2104 and holly set up.

Re: 5.7 2 barrel to 4
 

According to my notes on 5.7 LMerc cams:

Pre-Vortec with hydr flat tappet cam:
.004 " 270, 284
.006" 258, 270
.050" 200, 212
.400", .410" with 1.5
110 LSA

===============
Vortec hydr roller
.004" 258, 272
.006" 249, 264
.050" 197, 207
.430", .450
109 LSA

=================

Both leave a lot to be desired.

Re: 5.7 2 barrel to 4
 

Sounds like a pre-Vortec engine to me !!! A 2bbl 5.0 is rated at 250hp ? 5.7 near 270hp ? Correct ?

Vortec intake has just 4 ( 90° ) bolts attaching it to each cylinder head.

Pre-vortec (late model) has 6 intake to head bolts each side. (Outer 4 at 45° and inner 2 at 72°. )

Don't go by the valve covers - they are same on each motor.