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Discussion Starter · #1 ·
After weighing the pro's and cons for a long time I decided to convert my 2.5 to 3.0. Writing this mainly to help out people that are thinking about a conversion as well.

I knew the day was coming to go over the engine and had the opportunity from my mechanic to put in a 3 liter so I started thinking about the conversion with a bit of fear the character of the car would significantly change (although I don't mind a little more torque).

Here's the post:

After a NC500 trip the GTV6 was diagnosed with a leaking crack shaft ring and pretty much all the other gaskets had to be done.

I was still a bit on the fence whether I would either do just the gaskets in the hope the rest was good, do a rebuild of the 2.5, or go ahead with the 3.0. Like many, my mechanics advised to go with the 3.0 liter (new build) since if you would ever do it, it was pretty much now. They had a few laying around so we could find a good candidate and build a nice engine from the ground up.

It is going to be a 3.0 from a 75 (or Milano in US) with verde pistons (which I have no idea what the difference is). The heads are from the mechanic himself from way back when and have larger air intake pistons which supposedly is good for better airflow and a few horses.

I have the option to work in the garage myself in my spare time to clean up the engine bay and retouch some sections that can use some sanding and a bit of paint to prevent from rust.

If you're ever pulling the engine, try to put some time in and effort in the places you're not able to reach with the engine in (photo 8&9). These spots are particularly prone to collecting debris and water but are really hard to reach while the engine is in.

I'll keep people posted on this project. If there are any questions let me know! I'm really curious to see how this turns out. Thanks for all the feedback.
 

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I did this conversion, on this occasion I added a power steering, a very useful modification.

However, adapting the engine wiring harness to the vehicle wiring harness was not that easy because of the wire colors and connectors - the engine wiring harness of the 75/Milano is different in many ways.

Ciaoliviero
 
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Another option to consider, fitting an after-market ECU. Lots of variety to choose from to suit all sorts of budgets. I've had success with Link Engine Management from New Zealand. Fantastic product at a really good price. Another friend used Autronic, which worked well. Plenty of choices out there.
Going after-market EFI means you can do away with that pesky air flow meter. A lot better performance as well.
Good luck and have fun.
I'm also just about to add power steering to my GTV6. Can't wait to try it
 

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Discussion Starter · #4 ·
I did this conversion, on this occasion I added a power steering, a very useful modification.

However, adapting the engine wiring harness to the vehicle wiring harness was not that easy because of the wire colors and connectors - the engine wiring harness of the 75/Milano is different in many ways.

Ciaoliviero
Might sound strange, but I kind of like the heavy work at the wheel. I think I'll stay away from the power steering for now...
 

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Discussion Starter · #5 ·
Another option to consider, fitting an after-market ECU. Lots of variety to choose from to suit all sorts of budgets. I've had success with Link Engine Management from New Zealand. Fantastic product at a really good price. Another friend used Autronic, which worked well. Plenty of choices out there.
Going after-market EFI means you can do away with that pesky air flow meter. A lot better performance as well.
Good luck and have fun.
I'm also just about to add power steering to my GTV6. Can't wait to try it
I think this is something for the future. As it stands now I think I'll have a lot of fun with the power upgrade from the 3 liter and I won't be needing another ECU or injector system. I think I'll eventually run into this when I make the leap to upgrade to some quicker cams.
 

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Discussion Starter · #6 ·
Some new work:

  • Some fresh paint in the engine bay (color code AR 530)
  • Sonic cleaning of the block, oilpump and carter. I still think I'm going to sandblast the carterpan to make it even more neat.
  • Cleaned out all the oil channels in the crackshaft. My mechanic urged me to do this elaborately so I spent some time on this with brake cleaner and high pressure air.
-After cleaning we noticed there were some small dings on the crackshaft, where the bearing sits on top. I used some very fine grit sand paper to polish these sections.
 

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Discussion Starter · #7 ·
After some debate (GTV6 Manifolds). I decided to go with stock 3.0 manifolds from a Milano/75. The 2.5 manifolds are a bit smaller so according to my mechanic best to go with 3.0 manifolds (luckily he had them lying around). If you're doing fast cams when building up a 3.0 engine I think its better to go with equal length tubes manifolds. Personally for now, I think the stockish 3.0 engine should be fine with the stock ones.

Cleaned up the manifolds and sprayed some heat resistant paint.
 

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Discussion Starter · #8 ·
Today some work on the intake manifold and camcovers:

Since the Milano heads I'm using have some oversized valves I enlarged the intake plenum from 35mm to 39mm. It is a lot of work, took me about 2 hours non stop. After enlarging and sandblasting make sure you REALLY clean out the intake manifold with great care. If something like even a grain of sand or metal is still in there when you fire up the engine, chances are you mess up your cylinders right away. I used I bucket of soap, high air pressure gun and brake cleaner.

The camcovers and plenum were sandblasted. It gets dirty really quickly at this stage but my mechanic advised to spray them with a thick layer of WD-40. It makes the covers a bit darker, but it looks finished after doing this (not in these pictures).
 

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