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Ghibli de Hongrie [ENG]

C'est ici qu'on présente nos voitures

Re: Ghibli de Hongrie [ENG]

Messagede spacecadet » Mar 4 Déc 2018 09:11

Thanks for the suggestions. I will then also ask around for custom head gasket.
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Re: Ghibli de Hongrie [ENG]

Messagede alpa » Mar 4 Déc 2018 11:05

spacecadet a écrit:Thanks for the suggestions. I will then also ask around for custom head gasket.


I really don't see the point: you can not reuse pistons yet another time and skiming them is simple and free. Custom gaskets are expensive so why would you do that ?
If you are scared to disbalance the engine then think that many of biturbo engines have up to 5gr weight difference across the stock pistons.
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Re: Ghibli de Hongrie [ENG]

Messagede spacecadet » Mar 4 Déc 2018 19:11

I wasn't aware of that. Also didn't measure mine. I was expecting tighter tolerances because of the 4 different weight classes of rods and crank. Although the pistons have a smaller rotational mass and more reciprocating I guess that's why they were less conscious about them.
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Re: Ghibli de Hongrie [ENG]

Messagede alpa » Mar 4 Déc 2018 20:29

Yes there are classes for rods, they are heavy things.
Pistons and rods are MUCH lighter on Ghibli but the crank is the same as before ! We compared 2.8 18v and Ghibli cranks: same weight.
Don't tell me you are building a perfect engine while you have used 40 years old rings and you have a chamber disbalance.

If you are really worried about weight balance then remove some weight from the piston skirts on the other bank.
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Re: Ghibli de Hongrie [ENG]

Messagede spacecadet » Mer 5 Déc 2018 23:45

Found the two topics http://www.maseratitude.com/viewtopic.php?f=7&t=1666 and http://www.maseratitude.com/viewtopic.php?f=56&t=5645, lots of very useful and interesting information.

Yes, I was planning for the perfect engine. I know that rings are a slight compromise, but I wasn't expecting this disbalance issue at all :|

I might find a second hand head pair here, still waiting for the answer. Based on that I'll decide which way to go.
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Re: Ghibli de Hongrie [ENG]

Messagede spacecadet » Sam 23 Fév 2019 17:29

I'm pretty late with this, but after going back and forth wit the solutions, the cc volume mismatch was solved by minor adjustment in the cc itself. This brought everything in the required ±0.5 cm3 diff. And the heads can be reused in the future without having to touch any other part.

Image

One of the touched up cc

Image

As visible these were already touched up slightly in the factory, on some only machining marks are visible, but on some there are rougher hand made marks

Image

Heads are now installed, valve clearance measured. I have the new shims, they are just waiting to be installed in the coming weeks. Then set the timing and pretty much done with the engine.

Image
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Re: Ghibli de Hongrie [ENG]

Messagede Konimino2 » Sam 23 Fév 2019 19:04

Beautiful to see :Maze
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Re: Ghibli de Hongrie [ENG]

Messagede alpa » Sam 23 Fév 2019 20:49

Why not to machine the chamber. I'd rather unshroud exhaust valves instead of removing between them. These angles just above valves restrict the flow, removing them does not hurt.
But as I said I'd machine piston tops.
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Re: Ghibli de Hongrie [ENG]

Messagede spacecadet » Dim 24 Fév 2019 23:31

You mean to bevel / blend the edge right above the seats? I guess that would help for the flow, but not for my nerves if doing this after the valve job (wasn't done by me but still) :) This was a simple and fast solution. Just like the piston tops as you said, but I didn't wanted to disassemble the block again.
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Re: Ghibli de Hongrie [ENG]

Messagede alpa » Lun 25 Fév 2019 08:17

spacecadet a écrit:You mean to bevel / blend the edge right above the seats? I guess that would help for the flow, but not for my nerves if doing this after the valve job (wasn't done by me but still) :)


I don't see in what it would be different for your nerves from what was done.
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