Replacement motor going in ,need opinions

[crazy charlie]

One of my 1988 5.0XL 4bbl alpha ,needs replacement.Reputable boatyard has a very clean good running 2003 5.0 2bbl dry exhaust serpentine style from a bravo.He said that it should drop right in with a few modifications,mostly because of the alpha drive.I gave him the go ahead and he pulled my motor yesterday.Put the 2 side by side.determined that the height of the dry exhaust and the 2bbl carb having a spacer plate might be too tight for my engine compartment.Easiest solution looks to be pulling spacers from risers and carb.his tech made a suggestion of changing over intake manifold,carb ,fuelpump and he was still going when i interupted him and said that it seems like an aweful lot of work putting my old parts on this newer motor.he made reference to the new fuel pump being electric which may be an issue as well.Is my thinking incorrect to keep as much of new motor as possible with the least modifications possible and have a more modern setup?? I have no concerns that a 4bbl is much more desirable as we dont travel with the boat.Its more of a summer mini condo for us.What do you guys think?? Charlie

 

[Bondo]

Ayuh,..... Ya can't swap the carb, 'n intake Charlie, the new motor has Vortec heads, the old motor don't,......
The intake to heads bolt pattern is different, 12 bolts on the old motor, only 8 on the Vortec heads,....

 

[Lou C]

On your 1988 is the carb a Quadrajet? If so they use a well type choke which works with the pre-vortec just fine (these have an exhaust cross over in the intake to heat the choke & carb) but there is no exhaust cross over for the vortec heads/intake. So you'd have to either figure a way to convert the Rochester QJet to an electric choke or use an Edelbrock 1409 on a 4bbl Vortec intake.
Personally I'd think having one pre-vortec and one vortec is imbalanced, one engine will always have 20 hp more than the other, unless you put a set of Vortec heads and intake on the other one....
In this case the simpler plan might have been to get a reman 5.0 pre-vortec engine but sometimes you have to use what comes along.

 

[crazy charlie]

Ayuh,..... Ya can't swap the carb, 'n intake Charlie, the new motor has Vortec heads, the old motor don't,......
The intake to heads bolt pattern is different, 12 bolts on the old motor, only 8 on the Vortec heads,....

thanks,I would hope the tech would have already known that.any idea what year vortec begins?? Maybe they have the year of the newer motor incorrect??Charlie

 

[Bondo]

Ayuh,.... 1996,.....

 

[Lou C]

Its easy enough to check, your 1988 pre vortecs have the 12 bolt intake, a 2003 will be a vortec 8 bolt intake. If your other engine is still good I think you're better off getting a 5.0 reman to match it.

 

[crazy charlie]

On your 1988 is the carb a Quadrajet? If so they use a well type choke which works with the pre-vortec just fine (these have an exhaust cross over in the intake to heat the choke & carb) but there is no exhaust cross over for the vortec heads/intake. So you'd have to either figure a way to convert the Rochester QJet to an electric choke or use an Edelbrock 1409 on a 4bbl Vortec intake.
Personally I'd think having one pre-vortec and one vortec is imbalanced, one engine will always have 20 hp more than the other, unless you put a set of Vortec heads and intake on the other one....
In this case the simpler plan might have been to get a reman 5.0 pre-vortec engine but sometimes you have to use what comes along.

Yes I am using what started as the easiest approach thinking it was almost a "drop in".Most techs I spoke to over the past months didnt have any confidence in rebuilds and really seemed like they were not into that kind of job and this was in Feb ...a time where I assumed these guys would welcome the job...but not really.

 

[Lou C]

Well you can do it that way, use it and see if you really notice the difference in power between the 2 engines. If so use it that way for a season and then get a set of Vortec heads and intake for the other engine. If that engine is original it might need the heads freshened up anyway. You're in LI correct, there is a place in Deer Park (Machine World NY) that sells cyl heads, I think they are mostly reman units though. I got my 4.3 heads from them (Via SK Speed Shop in Lindenhurst) and they've been fine. The other option is to find a machine shop to rebuild your original but if it has been raw water cooled in salt they may not feel its worth it.
MERCRUISER 1996-2002 5.0 LTR - V8 cyl Cylinder Head - Casting : 059 (machineworldny.com)
here's an example, 96 and up Vortec V8 cyl head, in case you wind up doing a top end overhaul on your other engine to match the newer one being installed.

For sure I would not have a 2bbl on one side and a 4bbl on the other that will cause a noticeable difference in response I would think. So for that newer engine you need a 4 bbl Vortec manifold but keep in mind the choke that the old Quadrajet has won't work on that due to no exhaust crossover on the Vortec engines. So either you have to figure out a way to convert it to an electric choke or switch to an Edelbrock 1409 4bbl. That carb is very similar to the Weber 4bbl (really an old Carter design) used by Merc so the rigging might be easier than using a Holley.

When you upgrade an old boat there are always these issues, if I repower mine and if I want to go with new, then I have to use a different coupler, electric fuel pump, and a Holley 4bbl unless I can figure out a way to make an electric choke to work with the Quadrajet. When you go from a pre-vortec to the Vortec, there are a fair number of differences that have to be dealt with.

I know mechanics don't like remans but I feel the way around that is to use a good local machine shop. After all every classic car and hot rod, at least most of them, are running around with reman engines.

 

[tank1949]

One of my 1988 5.0XL 4bbl alpha ,needs replacement.Reputable boatyard has a very clean good running 2003 5.0 2bbl dry exhaust serpentine style from a bravo.He said that it should drop right in with a few modifications,mostly because of the alpha drive.I gave him the go ahead and he pulled my motor yesterday.Put the 2 side by side.determined that the height of the dry exhaust and the 2bbl carb having a spacer plate might be too tight for my engine compartment.Easiest solution looks to be pulling spacers from risers and carb.his tech made a suggestion of changing over intake manifold,carb ,fuelpump and he was still going when i interupted him and said that it seems like an aweful lot of work putting my old parts on this newer motor.he made reference to the new fuel pump being electric which may be an issue as well.Is my thinking incorrect to keep as much of new motor as possible with the least modifications possible and have a more modern setup?? I have no concerns that a 4bbl is much more desirable as we dont travel with the boat.Its more of a summer mini condo for us.What do you guys think?? Charlie

If fresh water boat, just rebuild it. Salt water... It depends on how much total it will cost for upgrade? Everything mentioned can be done. Electric fuel pumps for carburated motors must have a special oil sender cutoff switch to consider. Use marine electric fuel pump too. I assume newer motors has one. Don't install an automotive one.

 

[crazy charlie]

If fresh water boat, just rebuild it. Salt water... It depends on how much total it will cost for upgrade? Everything mentioned can be done. Electric fuel pumps for carburated motors must have a special oil sender cutoff switch to consider. Use marine electric fuel pump too. I assume newer motors has one. Don't install an automotive one.

Im not taking a chance on rebuilding it.I am leaving all the work to the boatyard.The newer motor is complete.Could be a complete drop in to the right boat but I will needs some mods.Motor is $3000 ,pull old motor and install newer one is $1500.Modifications are gonna be extra and since the boatyard owns the newer motor the owner assured me the cost of mods will be kept in check.New motor has elect fuel pump which is a mod to be addressed.Immediate issue that came up is the height of risers and carb.Dry exhaust spacers and carb spacer has to be removed for a better fit.So far that is the main issue.Charlie

 

[crazy charlie]

Got word "new" engine is installed and it fit fine with minimal mods.going to check it out today!! Charlie

 

[nola mike]

Got word "new" engine is installed and it fit fine with minimal mods.going to check it out today!! Charlie

If you're paying extra for the mods make sure you keep all the removed parts

 

[Scott06]

Got word "new" engine is installed and it fit fine with minimal mods.going to check it out today!! Charlie

Good to hear, the fuel pump should be handled within the existing wiring harness so i was confused by the mechanics comment. Hopefully it work$$ out Ok.

 

[crazy charlie]

Got a quick look today.They removed spacers on the risers and carb and it actually looks like it takes up a little less engine compartment .I didnt get a chance to ask bit I was lead to believe that the spacers under the risers are what made this "dry" exhaust. I have been dealing with the owner and sold me on the "drop in " engine so I dont think he is gonna try to ramp up the cost of the mods since he actually believed it was a drop in.Also my engine compartment access for the switch over could not have been any better making it much easier for them.When the tech first looked at my access he turned to me and thanked me.I included a pic of my access.Charlie

 

[achris]

No, the spacers under the elbows are called risers. Risers have no control on whether it's a wet joint and dry joint system. I'll post pictures shortly on the differences. Risers are to lift the elbows high enough so water doesn't flood into the engine due to the engine/water level relationship... Risers come in 3" and 6"...

 

[Rick Stephens]

Nice looking install.

From the outside is hard to tell if you have dry or wet.

 

[achris]

No, the spacers under the elbows are called risers. Risers have no control on whether it's a wet joint and dry joint system. I'll post pictures shortly on the differences. Risers are to lift the elbows high enough so water doesn't flood into the engine due to the engine/water level relationship... Risers come in 3" and 6"...

Here's a link to a document I just put together...

Mercruiser exhaust systems.

Exhaust systems 101 Mercury’s introduction of ‘dry-joint’ manifolds (and elbows) seems to have caused more confusion than it needs to. So let’s try to unpack that confusion, and understand what is essentially a very simple system. Before we go much further here’s a picture of the various parts...

forums.iboats.com

 

[achris]

Nice looking install.

From the outside is hard to tell if you have dry or wet.

They are 100% wet-joint exhausts...

 

[achris]

Got a quick look today.They removed spacers on the risers and carb and it actually looks like it takes up a little less engine compartment .I didnt get a chance to ask bit I was lead to believe that the spacers under the risers are what made this "dry" exhaust. I have been dealing with the owner and sold me on the "drop in " engine so I dont think he is gonna try to ramp up the cost of the mods since he actually believed it was a drop in.Also my engine compartment access for the switch over could not have been any better making it much easier for them.When the tech first looked at my access he turned to me and thanked me.I included a pic of my access.Charlie

You should measure your water level to make sure those engine aren't going to get flooded.

 

[crazy charlie]

Sorry guys,the pic is one of my original engines showing the easy access for an engine change.I will get a pic of my newly replaced stbd engine which was described to me as Dry joint exhaust which had a spacer of several inches between the manifold and riser.Charlie