5.7 Rebuild Questions

[pennyduke]

It is now time to send my 1996 5.7L vortec to the Machine shop for a Rebuild. It is from my 1996 Suburban and replacing my very tired 1993 5.0l mercruiser.They are going to bore it .030 over and and align the crank among other things. I have a shop that wants to sell me a engine kit that will create 340hp. The kit includes pistions that will increase my compression from 8.5 to 1 to 9.5 to 1 and a set of Stainless Steel Valves with upgraded valve springs. I'm worried about the Cam numbers. 224 degrees duration @ .050 and .461 lift intake and .450 exhaust. Will this cam work with my stock exhaust? I wanted to get some opinions from some of you great people on this site before I do anything. Thanks

 

[Alpheus]

Re: 5.7 Rebuild Questions

To much cam. I wouldn't change the compression numbers either, unless you want to run high octane gas. I bet by this summer that is gonna be almost 5 bucks a gallon. Keep it stock. The boost from a 5.0 to a 5.7 will be noticeable enough.

Should check here for a new engine. You could probably have one of these shipped to your front door for about the same price as your machine shop bill...

http://www.rapidomarine.com/default.aspx?p=/engines/default.aspx

 

[HT32BSX115]

Re: 5.7 Rebuild Questions

Howdy,

First of all, I believe you will have problems with a 9.5:1 compression ratio unless you use premium fuel (one detonation event will potentially destroy the engine)

You MUST use a marine (or RV type) camshaft if you do not want to ruin the engine due to reversion.

If the engine "kit" requires you to run the engine above 5000-5500 RPM to get that HP you're wasting your money. The engine needs to be "cammed" to produce the most torque at RPMs below 4500.

The engine from your Sub is a fuel injected engine. I'll assume that you'll be getting a marine carb and manifold for it?

If this machine shop routinely builds marine engines for Sterndrive applications, they should know what works and what doesn't.....


You'll get all sorts of suggestions but unless you're going with dry stacks, you're going to be somewhat limited with exhaust unless you have thru-hull exhaust...........and even with thru-hull, you have a potential for reversion because the continuously "wet" exhaust.


Good luck,


Rick

 

[TilliamWe]

Re: 5.7 Rebuild Questions

Yes, penny, to add to what HT is saying. If this shop is used to building drag-strip or circle track motors, do NOT buy their "340hp" kit. They need to know how to build MARINE engines. If they think they are the same as car applications, RUN AWAY.

 

[Bondo]

Re: 5.7 Rebuild Questions

It is now time to send my 1996 5.7L vortec to the Machine shop for a Rebuild. It is from my 1996 Suburban and replacing my very tired 1993 5.0l mercruiser.They are going to bore it .030 over and and align the crank among other things. I have a shop that wants to sell me a engine kit that will create 340hp. The kit includes pistions that will increase my compression from 8.5 to 1 to 9.5 to 1 and a set of Stainless Steel Valves with upgraded valve springs. I'm worried about the Cam numbers. 224 degrees duration @ .050 and .461 lift intake and .450 exhaust. Will this cam work with my stock exhaust? I wanted to get some opinions from some of you great people on this site before I do anything. Thanks

Ayuh,... That cam is abit tall,...
As the guys have said, shop for a RV/ Marine cut cam,...
Probably 214? to 218? duration, 109? to 112? LSA...

The 9.5:1 compression can be done with Vortec heads(which your's Should be), 'n D-dished pistons, with the Quench cut down to .043" to .046"....
Otherwise, detonation will eat up the motor, unless you're runnin' Hi-test gas...

Good Valves are never a Bad thing, though the stock 1s will work just Fine...

Btw,... 340hp is Marketing,... Not Dyno'ed...
Ya wanta Really make some decent Power,... Build in a Stroker Kit,....
A mild vortec headed 383 is an awlfully Sweet boat motor,...
Complete rotating assembleys ain't all that much money...

 

[pennyduke]

Re: 5.7 Rebuild Questions

Bond-O, What HP would I be at with a Stroker? I see most of them are well over 350 hp. If I have to be below 4500 rpms what is the best build for that range? Thanks

 

[Bondo]

Re: 5.7 Rebuild Questions

If I have to be below 4500 rpms what is the best build for that range?

Ayuh,... You want yer cam/ build to be for Idle, to 4800rpms....

The Stroker would be Capable of tearin' up yer Alpha, if Beaten, Severely...
With reasonably sensible operation, it'll be a Sweet package on the edge of reality....

 

[pennyduke]

Re: 5.7 Rebuild Questions

Thanks for all the imput and comments. Below is a list of what Im going to buy from the Machine Shop. I would like approval or more imput from you guys because you have never let me down. You all really know your stuff about Marine Motors. thanks Again, pennyduke

Piston Ring Set 0.030
hyper piston set 0.30
Main bearing set
Cam bearing set
Metal 3 piece timing set
Oil Pump
Brass Freeze Plug set
Marine Performance Cam 210 int, 216 ex. .435 lift int., 455 lift ex.
Roller Hyd. Lifter set
Marine Gasket Set
Valve Springs
Chrome Moly Steel Retainers
Hardened Valve Keepers
$500.00

 

[Bondo]

Re: 5.7 Rebuild Questions

Thanks for all the imput and comments. Below is a list of what Im going to buy from the Machine Shop. I would like approval or more imput from you guys because you have never let me down. You all really know your stuff about Marine Motors. thanks Again, pennyduke

Piston Ring Set 0.030
hyper piston set 0.30
Main bearing set
Cam bearing set
Metal 3 piece timing set
Oil Pump
Brass Freeze Plug set
Marine Performance Cam 210 int, 216 ex. .435 lift int., 455 lift ex.
Roller Hyd. Lifter set
Marine Gasket Set
Valve Springs
Chrome Moly Steel Retainers
Hardened Valve Keepers
$500.00

Ayuh,... That looks respectable...

 

[pennyduke]

Re: 5.7 Rebuild Questions

I read somewhere that if I have a closed cooling system(which i do), I don't have to worry about cam size or Reversion. Is this a true statement?

 

[muc]

Re: 5.7 Rebuild Questions

No its not.

 

[Bondo]

Re: 5.7 Rebuild Questions

I read somewhere that if I have a closed cooling system(which i do), I don't have to worry about cam size or Reversion. Is this a true statement?

Ayuh,... Completely Irrevelant...

 

[Don S]

Re: 5.7 Rebuild Questions

No its not.

To explain WHY it's not. You still have raw water going through your heat exchanger and manifold and risers or just the risers alone, and on out of the boat through the exhaust. The water cools all the hoses from the exhaust riser.
The water coming out of the riser is where reversion takes place, it's not from sucking water up out of the lake.

 

[Bondo]

Re: 5.7 Rebuild Questions

To explain WHY it's not. You still have raw water going through your heat exchanger and manifold and risers or just the risers alone, and on out of the boat through the exhaust. The water cools all the hoses from the exhaust riser.
The water coming out of the riser is where reversion takes place, it's not from sucking water up out of the lake.

Ayuh,... muc didn't post a quote, but I'm guessin' his responce is to This,...

Is this a true statement?

It's Not a true statement...

 

[pennyduke]

Re: 5.7 Rebuild Questions

This is what I found on this site. Maybe I read it wrong. Thanks everyone.

"If you are dumping this kind of resources into a stroker consider putting a closed cooling system on it. If so cam it up"

 

[Don S]

Re: 5.7 Rebuild Questions

This is what I found on this site. Maybe I read it wrong. Thanks everyone.

"If you are dumping this kind of resources into a stroker consider putting a closed cooling system on it. If so cam it up"

Which site are you referring to, here at iboats???? It may be hard to believe, but there are people that post what they think are facts that have nothing do with the truth. Post a link to where you read it, may also be talking about something completely different.

 

[Alpheus]

Re: 5.7 Rebuild Questions

This is what I found on this site. Maybe I read it wrong. Thanks everyone.

"If you are dumping this kind of resources into a stroker consider putting a closed cooling system on it. If so cam it up"

I wrote that statement in September of last year in This Thread. If you would have continued reading down a couple of posts, you would have seen I retracted my statement. I was thinking of using dry stacks with closed cooling. Don't stop reading when you find the one statement that says exactly what you want to hear while disregarding the hundreds of posts that are telling you that you are heading down the wrong path...

 

[pennyduke]

Re: 5.7 Rebuild Questions

Sorry Alpheus. I was up reading all night and missed it. I did not mean to start any crap. I was thinking of stroking this Vortec motor and got real confused.

 

[Alpheus]

Re: 5.7 Rebuild Questions

Its all good. Just listen to the advise given to ya. If we didn't care what happened you would have allot of responses to your question telling you to put the biggest cam you can find in there. We are just trying to get you out on the water having fun and not swearing at your boat while its broken sitting in the driveway. Good luck...