Swapping a 5.7 to a 7.4

[180shabah]

Re: Swapping a 5.7 to a 7.4

6 bolts per side. I don't even think I have a roller cammed 5.7 either. However the good thing about a lame 2bbl 5.7 is the awesome fuel economy. I've had a few seasoned boat passengers compliment my boat being real easy on fuel for a "V8"

Now we have room to play (with YOUR money)....

Vortec heads(get a junk yard set rebuilt, no need to spend a fortune here), good aluminum intake manifold and 4bbl carb(recomend edelbrock for both) will net you just shy of 300hp at the prop, it will also be slightly lighter than your current setup and economy will not suffer IF you can control your right arm. Economy is directly related to how much power is being produced/used NOT how much power is available.

 

[chiefalen]

Re: Swapping a 5.7 to a 7.4

What shabah said ^. Getting to be a habit with me. Ha.

Well said again. I agree totally .

 

[180shabah]

Re: Swapping a 5.7 to a 7.4

 

[Polar_Bus]

Re: Swapping a 5.7 to a 7.4

Thanks a ton guys for all the education.

My last question, are there special "marine" intake manifolds or will a std. street version suffice?

 

[mkast]

Re: Swapping a 5.7 to a 7.4

Mercruiser intake manifolds have the coolant passages lined with brass for operation in saltwater.

 

[180shabah]

Re: Swapping a 5.7 to a 7.4

Polar - We don't know where you are(haven't updated your profile yet) but if you boat in fresh water or have fresh water cooling(uses anti-freeze) then ANY manifold will work. An iron, or bronze lined aluminum, will be needed if you are raw water cooled and boat in the salt.

With that said, I still like the Edelbrock performer, but all the aftermarket guys have manifolds for low RPM (idle - 5500) power.

 

[Bondo]

Re: Swapping a 5.7 to a 7.4

I still like the Edelbrock performer,

Ayuh,...

For Sweetwater boating,... It's pretty tough to beat....

 

[Polar_Bus]

Re: Swapping a 5.7 to a 7.4

My boat goes in the ocean, and I don't have a F/W exchanger system.

However if I did spend money on a manifold I would simply KREEM the insides of the coolant passageways. KREEM is an awesome epoxy like liquid kit used to coat the inside of metal motorcycle fuel tanks to eliminate mositure corrosion.

 

[chiefalen]

Re: Swapping a 5.7 to a 7.4

Polar high 5.

Don't get me wrong on this, seeing your a biker, knows hogs good.

Why don't you try something before you start kreeming all over the place.

Got a old bike tank laying around?

Put that snake oil, kreem or whatever you want to call it in the old tank.

And dip it in the ocean for say hmmm 1 hour and pull it out and leave it in your garage overnight and get back to me, what it looks like inside?

I ask you to do that cause you might not believe me when i tell you what i think it's gonna look like.

 

[Bondo]

Re: Swapping a 5.7 to a 7.4

However if I did spend money on a manifold I would simply KREEM the insides of the coolant passageways. KREEM is an awesome epoxy like liquid kit used to coat the inside of metal motorcycle fuel tanks to eliminate mositure corrosion.

Ayuh,... I'm familiar with the stuff,...

I'd give it Less than a season, before it peels Off,+ starts clogging up the passages.....

 

[180shabah]

Re: Swapping a 5.7 to a 7.4

My boat goes in the ocean, and I don't have a F/W exchanger system.

However if I did spend money on a manifold I would simply KREEM the insides of the coolant passageways.

Or you could stick with what works - use an iron manifold.

 

[Polar_Bus]

Re: Swapping a 5.7 to a 7.4

Ayuh,... I'm familiar with the stuff,...

I'd give it Less than a season, before it peels Off,+ starts clogging up the passages.....

So, KREEM can withstand fuel but will peel off from salt water corrosion????

Sorry this I completely do not understand. I have KREEMED 5 fuel tanks, and 1 did not come out right. Why? because I RUSHED the preparation of the tank. This is the #1 reason a KREEM kit wont work. If you can't get the metal surface SPOTLESSLY clean with the acid wash, the epoxy will never completely take. I am wondering if an intake manifold passageway simply itoo much of a challenge to rid the walls of rust and debris?

 

[chiefalen]

Re: Swapping a 5.7 to a 7.4

Try it on a old tank?

Put it on the right way, the way you said you knw how to do, make no mistakes
with the application.

And go dip it in the ocean say overnight tie it to the dock or something, make sure it's saltwater not fresh water, cause freshwater won't rust it like saltwater will.

Take pics before and after, maybe you finally found the magic cure for rust in the manifold and risers, that man has been looking for, before time recorded.

 

[45Auto]

Re: Swapping a 5.7 to a 7.4

I've used Kreem many times. Best product I've found for what it's designed to do. Now heat your gas tank up to a couple of hundred degrees and hit the Kreem inside it with a sandblaster. See what happens.

A couple of things it's NOT designed to do is to stand up to 200 degree engine temperatures while resisting abrasion caused by sand, upstream rust flakes from the head and block, seashells, etc, being pumped through the cooling passages.

I'm with Bondo and Chiefalen. I'd give it a season or so and the corrosion is going to work it's way under it through the scratches caused by the crap in the water then it's going to be peeling off and you'll be posting as to "why did my engine overheat"?

Edit: You might find this Kreem test on their website informative.

http://www.kreemproducts.net/pdf/KreemTestReport.pdf

Pay close attention to where the 3% salt water (seawater averages 3.5% salt) in either unleaded gas, leaded gas, or diesel turned the Kreem brown and showed corrosion around the edges after 7 days of exposure. Don't even need it to be scratched up. Now imagine it in a 200 degree environment with all kinds of abrasive crap being pumped across it .....

It's not affected at all by hydrocarbons (gas and oil, like you'd find in a gas tank .....), but IT'S NOT DESIGNED TO RESIST SALT WATER!!

 

[abj87]

Re: Swapping a 5.7 to a 7.4

Or you can avoid all this and switch to FWC which will help your engine last longer. Raw water cooled engines in salt water just dont seem like a good idea, your always fighting with thermostats and rust issues.