Ben's Maserati Biturbo Spyder

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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Mon Aug 28, 2017 9:34 pm

Yeah, I was pretty worried that I'd have trouble with the heads but they popped right off. No trouble at all!

I have the new head gaskets and valve seals on order to show up by the weekend.

I believe I found the issue - a broken valve stem seal on one of the intake valves for Cyl #4:
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Hopefully I'll be up and running before Labor Day
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Re: Ben's Maserati Biturbo Spyder

Postby GTJeff » Tue Aug 29, 2017 3:42 pm

Nice project, I have always thought the Biturbo is pretty cool.

Those are cast iron liners correct? Although they are probably pretty well stuck I would still recommend some hold downs like this:
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Good Luck!

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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Tue Aug 29, 2017 3:59 pm

Yeah - I had the same thought and put some on there last night!
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Sat Sep 09, 2017 3:39 pm

I got the whole thing reassembled last week and it still smoked like crazy.

Pulled it back out and disassembled today - stuck oil ring on Cylinder #4:
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Re: Ben's Maserati Biturbo Spyder

Postby DE80q » Sat Sep 09, 2017 4:16 pm

You just can't catch a break on this car! You sure are a gluten for punishment though. I commend your efforts!
"If you can't find one, make one"

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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Sat Sep 09, 2017 4:26 pm

Yeah, I think I have it all figured out now though! Just waiting on a new set of rings and then to reassemble
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Wed Sep 13, 2017 7:34 am

Rings now installed:
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Cylinders Honed:
before and after here:
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Now just waiting on some loctite 510 to join the two halves of the block back together and then I'll get it all back together and in the car.

I think someone has rebuilt these turbos before me - they have zero shaft play and spin great. Also I took the housing apart on the one and it seems to have a non-original bead of RTV on it.
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Re: Ben's Maserati Biturbo Spyder

Postby GTJeff » Wed Sep 13, 2017 11:50 am

You may want to consider replacing the rubber o-rings that seal the liners to the block now that you have the engine apart. Cheap insurance at this point. FWIW I have only rebuilt an Alfa V6 which uses a similar wet sleeve design but is a one piece block .
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Wed Sep 13, 2017 12:21 pm

That's not a bad idea. I need to figure out if I can even buy them

the two piece block is super weird. it makes assembly very strange as the bearings need to be stuck to the bottom half of the engine while I hold it upside down for install. Damn Italians!
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Mon Sep 25, 2017 9:06 pm

Deep into the most annoying part of this project yet - and that's saying something

These engines require that the clearance from the cams to the "cup" lifters be set to a close tolerance. The intake between 0.31 and 0.39 mm and the exhaust between 0.41 and 0.49mm.

To achieve this, you need to place the proper thickness shim on the end of the valve stem (one for exhaust, two for intake)

Mine were all wrong of course so I'm working on it now:

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To make matters more annoying, you can only check the clearance with the cam box torqued down to the heads so I've had it on and off probably 10 times the last week or two while I slowly deal with this.

These engines are so weird. Turns out its the first ever 3 valve per cylinder engine ever mass produced (as well as the first twin turbo)

The image below shows the way the three valve works. Valve shims in red, cup lifters in blue, valve stems in yellow. The exhaust lobe only opens one exhaust valve so the stem is long and sits centered in the middle of the underside of the lifter cup. For the two intake valves, the lifter cup has thicker walls and the two valve stems hit opposite sides of the lifter cup on the thickened walls. So odd
Image
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Re: Ben's Maserati Biturbo Spyder

Postby GTJeff » Wed Sep 27, 2017 11:10 am

FYI you may be able to grind the shims by hand with fine grit wet dry sandpaper against a flat surface. That's how I did the intake shims for the Alfa.
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Wed Sep 27, 2017 11:15 am

I've done that for a change of 0.05mm or so. I'm not super comfortable doing much more than that. Amazingly, the vast majority of the shims I have from this engine and the bad engine I harvested the others from are all a bit too small. I have another shipment of what I hope to be the last ones coming my way before the weekend. then I can finally install the engine again and get this thing moving!
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Re: Ben's Maserati Biturbo Spyder

Postby the german » Wed Sep 27, 2017 11:22 am

man, you really are a glutton for punishment with this thing. I know I would have thrown in the towel on the Maserati engine and just thrown a 1.8T in a long time ago so good on you for sticking it out. Good luck sir!
Kirk

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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Wed Sep 27, 2017 11:44 am

can't stop until it's done!

I may sell it immediately though. we'll see.

I currently have two convertibles - one has to go
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Re: Ben's Maserati Biturbo Spyder

Postby the german » Wed Sep 27, 2017 2:27 pm

yeah that's understandable. its turned into a pretty expensive $1500 car at this point LOL
Kirk

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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Sun Oct 01, 2017 9:02 pm

Got this thing running today and put about 15 miles on it.

A couple issues to work through: a heavy bogging down when going uphill or mashing on the gas pedal. not sure why yet.
runs decently on flat or downhill roads

A couple pics:
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Re: Ben's Maserati Biturbo Spyder

Postby ChrisAudi80 » Mon Oct 02, 2017 12:42 am

Nice. Your hard work is paying off.
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Re: Ben's Maserati Biturbo Spyder

Postby the german » Mon Oct 02, 2017 4:21 pm

sweet! good work
Kirk

1990 ABZ CQ
1990 lifted CQ
2005 S4 6MT
2011 A4 2.0T Avant (ok, it's my wife's car but it's sexy and I love it)
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Sun Nov 26, 2017 9:04 pm

If only this had been a happy ending at the time of the last post...

I drove the car a bit more in early October and I was hearing a lot of valve noise. Turned out that I had zero oil going up to the head on the driver’s side so - engine out again to try and figure out why.

I believe the culprit was an overly aggressive application of the Loctite flange sealer on the two halves of the engine block. There are little grooves behind the main bearings that channel oil up to the top half and then up to the head and there was some loctite visible blocking at least part of that channel. For good measure I also replaced the main bearings this time around since I realized that too much clearance between the crank and the bearings could also cause this problem and there was definite wear on the mains.

Got it all put back together and no smoke, plenty of oil and I still had the bogging down issue.

I was able to isolate it to a fuel problem and it turned out to be a bad vacuum hose routing. The carburetor requires about 3 psi of fuel and when the engine is at boost the Rising Rate Fuel Pressure Regulator increases the fuel pressure by the amount of boost. Otherwise, bogging! I had the routing wrong and it turned out it wasn’t getting vacuum or boost at all.

Anyway, I love the fixes that are free and simple. Teed off the manifold and Voila!

I drove the car yesterday and today quite a bit and I have to say it’s pretty awesome.
I got new tires on it Friday and took the plenum back off today to give the carburetor a better idle tune and it is running pretty well now.

It’s a keeper!

So now I have to figure out what to do with the 5 speed Cabriolet. I definitely don’t need 2 convertibles and the wife can drive the Maserati since it’s an automatic. Also I have to say the Maserati is WAY more comfortable than the Cabrio. The interior really is pretty amazing. Plus - the tiny turbos are actually kind of quick!

The clear coat is falling off the Cab at an alarming rate and while it runs well I expect that I would be better off taking the euro bumper, rs2 lights and the JHM short Shifter off, part what I can and scrap it. I don’t expect anyone to spend the $2,500 or so that I think the parts and scrap value are.
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Sat Dec 16, 2017 5:53 pm

I set about re-organizing my parts stash and bringing more from the basement into my new garage and part of it was to put the old bad engine away. It was in pieces but I still couldn't get the heads off.

So now with nothing to lose, I beat and pried them off.

As I expected, there was a white coolant "glue" residue on the middle two head studs:

Image

it was REALLY hard to get these separated. If I were to reuse this block and heads, I would have to re-deck both to get the pry marks off
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Re: Ben's Maserati Biturbo Spyder

Postby ChrisAudi80 » Sun Dec 17, 2017 3:00 am

Man, really dedicated.
96 S6 auto
95 80Q AEB VEMS
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Re: Ben's Maserati Biturbo Spyder

Postby Grillage » Sun Feb 25, 2018 10:14 am

I've been driving this thing bit by bit and figuring things out.

While sitting through the winter the exhaust got a little holier:



So I went through the process of trying to find pipes and had resigned myself to having it made when I found a guy that had a new pipe in the box.

Here's what the old system looks like after the pre-cats (which I hollowed out):
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The main catalyst had a large piece of the pre-cat impacted into and blocking about 25-30% of the fins in the main cat so this was a pretty restricted system.
Also, there was a not so small pile of rusted metal and dust that came out of the pipes and the muffler itself. I need to replace the muffler now that I have taken it out and can only compare it to a maraca now.

I have that coming as well now.

I gutted the main cat too now and I will have a very non-restrictive system when I'm done!
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Re: Ben's Maserati Biturbo Spyder

Postby 90quattrocoupe » Sun Feb 25, 2018 11:06 pm

Is there a purpose for that one exhaust pipe having a big loop in it?

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Re: Ben's Maserati Biturbo Spyder

Postby ChrisAudi80 » Mon Feb 26, 2018 2:20 am

90quattrocoupe wrote:Is there a purpose for that one exhaust pipe having a big loop in it?

Greg W.


It's an Italian car.
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Re: Ben's Maserati Biturbo Spyder

Postby elaw » Mon Feb 26, 2018 8:19 am

90quattrocoupe wrote:Is there a purpose for that one exhaust pipe having a big loop in it?

Greg W.

Crude seat heater? :lol:
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