4.3 to a 5.7 vortex engine

zell66

Petty Officer 1st Class
Joined
Jul 6, 2007
Messages
211
Toying with a idea of upgrading my motor. I currently have a 1996 Monterey 230 Explorer with a 4.3 l Chevy vortex engine. Thinking of upgrading to a (auto) 5.7 vortex from 1996 or 97. The new engine in from a auto and would need to be retro fitted for marine application.

1. Is it cost effective to fit necessary equipment to transform auto to marine engine?
2. Will the boat take a 5.7 with minor changes to motor mounts?
3. If I move forward what would be a reasonable price to ask for my 1996 4.3 l vortex engine that runs flawlessly?
 

bajaunderground

Lieutenant
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Apr 18, 2008
Messages
1,401
My $.02 worth of input. Depends? The 4.3L sounds extremely small for a 23' boat, that being said, I'm sure it moves it okay, just not gonna break ANY speed records.

The 5.7L would be an upgrade for sure, but add for Manifolds, risers, mounts, intake, FI or Carb. Marine starter, Marine carb, etc...is the adapter compatible? Correct flywheel? the list goes on and one. IMHO, unless the motor was close to free, I'd think an used marine motor set-up would most likely be a better option?

Search CL, ebay and other sites that might have a used marine set-up? The out drive might need replacing as well, as the SX ratio might be too aggressive for a 5.7L, maybe?

I have no idea what a 4.3L would be worth, where are you located would help determine the market. a guesstimate would be $1,500-$2,000 with all the manifolds, intake, etc...
 

zell66

Petty Officer 1st Class
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Jul 6, 2007
Messages
211
Thank you for the info. Location is in Central Wisconsin.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Jul 23, 2011
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47,303
A new vortec 5.7 longblock is about $2500. Building a 383 stroker longblock is about $2200 ( since your in Wisconsin, use either Manitowoc Motor Machining and Parts - talk to Jake or Scotty, or use Baril engin service in Green bay)

A pull-out low mileage runner will be about $1000 (core motors are $450), need $120 in gaskets, core plugs and cleanup.

Then to that, you need to add the following:
V8 dizzy - $350
Intake manifold -$350
Exhaust manifolds and risers - $600
Misc - $500
Carb? - $600

Then need to check ratios in drive like Baja mentioned

Or you find a complete drop-in ready motor from a boat salvage yard such as green bay propeller for about $1500 ($3000 with drive)

Your 4.3 stripped of front accessories and mounts is worth about $1000 to the right buyer, however you will sit on it for a while. It would sell at $500. Check CL. The 4.3 complete with drive would eventually sell at between $1500 and $2000

I have a bunch of stuff on CL in Wisconsin trying to clean out my storage of a variety of automotive and boating parts and projects and the stuff just isnt moving ( and my prices are currently equivalent to scrap value at $.30/# )

If you absolutely love the boat, and will keep it for a long time, then make the swap. If you are even remotely thinking of a different boat, go that route
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Just so you know, in 1996 it is not likely that you even have Vortec heads. They didn't really hit boats until 1997 even though autos had them in 96. you need to check and see what you currently have. If you don't have them right now, you could upgrade to Vortec and get a little more power.
 

zell66

Petty Officer 1st Class
Joined
Jul 6, 2007
Messages
211
Scott, Yes we plan on keeping boat for a long time. Boat in in excellent shape and no rot. Where on CL is your stuff?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,303
Appleton, Green Bay and Fondy Craigslist sites. My storage is in Maribel.

I have a 502 that im selling for a friend, a pair of 088 heads, a pair of marine gears, the top end of a mercruiser 8.1, my opel gt project with supercharged Northstar and a few other items. They have been on and off CL for years

Cheapest salvage yard for a truck motor would be Gibsons in Neenah. However would be hit or miss. Stay away fro Schmitys in GB. Norb's in Denmark is OK. However i would bid on a wreck on ridesafely, then strip it
 
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