5.0 to Vortec 5.7 swap

[AL.Longshot]

I just acquired a 1995 Caravelle BR19 that the previous owner failed to properly winterize and the factory 305 froze and busted the block. We (previous owner and myself)tried to fix the crack on the outside and the engine ran great on the muffs and in the water, but after about an hour on the 2nd outing we discovered water in the oil. Owner got mad and sold it to me.
So now I have plans to swap out the 5.0 of a 1996 Vortec 5.7.
Other than the obvious intake issues is there anything I should look out for?
Will the jump from the 190hp 305 to the 255hp 350 be an issue for the Alpha 1?
Should I keep the quadrajet carb and rejet it or swap to the Edelbrock?
The engine is from a truck so should I swap the cam or will the factory truck cam be ok?

Thanks for all the insight and tips!

 

[AL.Longshot]

Here's a few pics of the boat, the crack and after grinding off the paint we found the crack to be much worse than believed. We patched it up with JB Weld in an attempt of a cheap easy fix.
Luckily the owner did drain the manifolds so I don't expect any damage to them and no leaks were found during the prior outings

 

[Skyhead22]

Stock cam is perfectly fine. You start running into reversion issues above 230 degrees duration at .050
The cam in your stock 350 should be right around 200 duration at .050".


A quadrajet from a stock 305 will do just fine on a stock 350. If your edelbrock is no bigger than 650, it will do fine too.

Youll need to get a carb intake manifold that bolts onto vortec heads.

Pretty sure a vortec 350 block is not made to fit a manual fuel pump, i think youll need to run an electric fuel pump.

The alpha one drive will hold solid up to 400 horse. Even beyond 400 horse it will still hold up well if you treat it right.

If youre carb swapping a vortec, you may as well rebuild it and put in a good cam. With just carb and cam swap on a vortec you can easily touch 400 horse.

 

[Scott06]

Drive ration may be different on 5.0 vs 5.7. Most 5.0 I've seen in similar size boats have a 1.62:1 , where the 5.7 will have a 1.47:1. Mist likely you can just go up in pitch. I just dud a 4.3 to 5.0 swap fir same reason in by sea ray 200 sport. Went from a 19" pitch to a 21" pitch to keep WOT rpms at 4800. Just watch rpms when you take it out and adjust pitch as needed .

 

[Scott06]

Yes my auto correct is killing me ...

 

[Scott Danforth]

You're swap is fine. You may or may not have a mechanical fuel pump pad machined on the 1996.

Your alpha drive will be fine. You may have to reprop for the 5.7 since the 5.0 ratio is normally 1.62 and the 5.7 is normally 1.47.

Most you will need on the carb is different calibration kit.

If you have the 5.7 out, you can swap a cam, however not needed unless you want a bit more power.

Even though you believe the manifolds and risers are ok, I would still do an acetone test.

 

[AL.Longshot]

Ok so I picked up a Vortec motor out of a 98 Z71. I decided if I'm gonna go through all this work to replace the engine why not upgrade a bit..
I'll keep the updates coming

 

[harleyman1975]

As far as I know Z71 is just off road suspension and skid plates engine is the same.

 

[AL.Longshot]

Well crap.... the 305 only has a 2 barrel carb, I really don't know if it will be big enough to work on the Vortec 5.7.and don't even think they make a 2bbl intake for them, so looks like I need to buy a carb too.
I already know that I have to install an electric fuel pump and have read about USCG regs that say I need to use a specific kind of pump. Any help on those would be great appreciated.
I had the option to purchase the ECM and wiring harness from the truck this motor came from wish I would have now... fuel injection would be very nice. Alot of work but very nice and fuel economy I would expect to be a good bit better.

 

[jimmbo]

Other than the obvious intake issues is there anything I should look out for?
Will the jump from the 190hp 305 to the 255hp 350 be an issue for the Alpha 1?
Should I keep the quadrajet carb and rejet it or swap to the Edelbrock?
The engine is from a truck so should I swap the cam or will the factory truck cam be ok?

Thanks for all the insight and tips!

Parts on the truck engine that have to go... Core plugs, water pump, Myself I would get a new cam and lifters from mercury. I know a few people will post the 'Truck' cam is the same as a marine cam. It is NOT the same, close, only counts with Horseshoes, Grenades, and Nuclear Weapons. Using the truck cam will weaken the holeshot, and provides no increase in top end to compensate.
The Vortec Heads are a nice improvement.

 

[jimmbo]

Well crap.... the 305 only has a 2 barrel carb, I really don't know if it will be big enough to work on the Vortec 5.7.and don't even think they make a 2bbl intake for them, so looks like I need to buy a carb too.
I already know that I have to install an electric fuel pump and have read about USCG regs that say I need to use a specific kind of pump. Any help on those would be great appreciated.
I had the option to purchase the ECM and wiring harness from the truck this motor came from wish I would have now... fuel injection would be very nice. Alot of work but very nice and fuel economy I would expect to be a good bit better.

Volvo makes a very nice 4bbl manifold for the Vortec V8. It would fit your crusier. My 5.7 Volvo came with it and used an adapter to mount a 500 cfm 2 bbl Holley. This carb is the perfect size for 305 turning 5000 rpm but falls a little short of what a 350 needs. I did buy a Holley 650 cfm spreadbore and it installed on my unit very easily. I did gain 400 rpm from the swap. I did increase the pitch by 2 inches and brought the rpms back in line but at the risk of poorer holeshot. The tiny primaries on the spreadbore did help the bottom end and my holeshot wasn't much weaker.
The manifold with 2bbl


The 4bb holley 0-00552

 

[Scott06]

Get a vortex 4 bbl intake from Michigan motorz and an edelbrock 1409 it will run good out of the box and factory merc linkage parts will fit up perfect if you use merc throttle bracket part number 805953T. Easy to change metering rods in the 1409 to riches or lean mixture if needed.

 

[AL.Longshot]

My block is an 880 Vortec block. It has the hydraulic roller cam and lifters, and a windage tray in the oil pan. The factory cam specs are 191?/196? 0.414"/.428" lift on a 111? LSA. I'll admit it is abit weak but unless I'm going to really see some significant gains in power by swapping cams I really can't justify the expense and I'm already adding 65hp with the new motor in stock form. So are the factory marine cams really that much different? Im fairly certain the cam in the busted 305 is not a roller or I would just swap it into the new motor. I am aware that both cams will work in my block but I really don't want to deal with pushrod lengths and rocker arm issues.

 

[jimmbo]

The lobe separation angle is fine for a marine engine, the duration specs are rather meaningless without a reference, Ie the stock hydraulic roller cam used in 305 and 350 marine engines
197 degrees intake duration measured @ 0.050" lift
249 degrees intake duration measured @ 0.006" lift
258 degrees intake duration measured @ 0.004" lift
207 degrees exhaust duration measured @ 0.050" lift
264 degrees exhaust duration measured @ 0.006" lift
272 degrees exhaust duration measured @ 0.004" lift

0.430" intake lift on 1.5:1 rockers
0.450" exhaust lift on 1.5:1 rockers

The stock Hydraulic tappet cam has a 3 more degrees of duration@ 0.050 lift on the intake side but less lift, 0.400 with 1.5:1 rockers
It also has 5 degrees more duration @ 0.050 lift on the exhaust side but less lift, 0.410 with 1.5:1 rockers



Try the cam that comes with your replacement engine. It isn't that hard to change a camshaft, well it can be if some idiot designer put a bench seat ten inches in front of the water pump pulley. Make sure you replace all the core plugs with brass ones, and if it is good shape use the water pump off of the 305, ashcan the one that's already on the engine

FYI. The vortec does have a larger Harmonic Balancer and a plastic timing chain cover

 

[thumpar]

You wouldn't want to try using the truck ECM. It uses 1 or 2 O2 sensors that would not be installed on your boat. The programming is probably way off too. Road vehicles rarely get above 2500 RPM. Boats normally are around 5000 RPM WOT.