Maseratitude

Thanks for the suggestions. I will then also ask around for custom head gasket.

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.

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.

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.

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.

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.



One of the touched up cc



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



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.

Beautiful to see

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.

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.

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.

After the long silence wanted to give an update, and ask for some more help.

The engine was finished in May, and then it took me some more time to install all the accessories on it, and finish the engine bay. The engine was back in the car in June, cleaned all the cooling system, air pipes, and started up for the first time in July. Got some serious noise, which turned out to be the CO.ME clutch set which is not fully compatible. Instead of tweaking it, gearbox up and down is not so funny on jack stands, the original Sachs set was refurbished and I've installed it. I did source a new release bearing (Sachs 3151 600 781), which despite being a remanufacture of the original, still needed some adjusting, cutting and griding here and there. I was able to get one of the last ones, but unfortunately it seems this is again not available, only for stellar prices.



So I replaced the clutch set, reinstalled the gearbox, started the car up without the exhaust (to verify the operation of clutch before reassembling everything) and the turbos were spitting out quite a lot coolant on both sides. I can see drops on the top of the pistons and on the spark plugs too.



I did a leakdown test, on the right side, there were no bubbles coming up in the expansion tank, but the coolant level did increase. During engine rebuild I didn't remove the liners, there were held down with washers and nuts. It's not possible that they sink down right? There should be a lip on the bottom I guess. The block also wasn't touched, so they also can't protrude above the deck surface. Any idea how coolant gets into every cylinder on both sides? I can't see how this is happening with resurfaced and straight heads and new gaskets.

Hey,
What do you mean a leakdown test ? Compression test and checking the water level ?
Of course liners can not sink, they should be able to stand tons of force from heads.
Who mounted heads ?
I don't think the problem could be on the head gasket side, today there is no mystery in the composite gasket technology. If they were properly installed and torqued they should not leak. And the probabilty to have leak on all cylinders is close to zero.
Are you sure to have the 2L and not 2.8L gaskets ? 2/2.8 heads are identical but the bore is different.

On leakdown test I mean putting compressed air into the cylinders and checking how much air escapes.

Gaskets were good for sure, I received the 2.8L gaskets first, wanted to replace with 2.0L, but wasn't available from the factory, found reproduction at Candini, that's what I used.

I mounted the heads and today I think I found the problem: improper torque. Back then I waited half a day between the 2nd and the final stage and I remember when doing the final stage the nuts slightly moved before the torque wrench clicked, I think the were "sticking down".

When retorquing the heads, I loosened the nuts one-by-one (in assembly order) by 45 degrees to get rid of the breakaway torque, but when tightening back to the necessary 90Nm, nearly all of them turned approx. with a further 45 degrees. I don't know how much additional torque that means, guessing 15-20Nm. This could probably lead to a leak on all cylinders.

Did you oil head nuts and washers ? Strangly the biturbo workshop man says to oil for 18v heads but does not for 24v heads. While most of engines require oiling. Additionally you have custom made gaskets so what did they say ?
Because if you have not oil while you should the torque level you applied would be insufficient.

Yes, I've lubricated studs, nuts, and washers, not with oil but with grease.
The gaskets are interchangeable with the factory provided ones, same process can be used.

Well you should use engine oil, this is standard on car engines. But grease is still better than nothing.

I've used grease with moly content, but right, oil is more common.

Checked the 24v manual, it says "lubricate the studs, washers and lock-nuts", so that's in line with the 18v manual then.

Anyway, unfortunately retorquing didn't help, so I'll pull the engine in a hope that removing the heads will reveal something

That's a bummer.

I'm sure it's possible to remove the heads without removing the engine. They did it with my first ghibli.

On Ghibli it'll take less time to remove the engine.

Sounds interesting, do you have any further information maybe?

RH side seems doable, but on LH side - even if the ABS and brake master cylinder are removed, which are in the way to easily remove the exhaust manifold - the brake booster seems to be interfering with the head.