ALFAGTV6.COM

I can't make up my mind where to put this info. Does it warrant a topic of it own, dunno.
I seem to be plagued by engineering shop shortcomings and now out of the blue, I have an engine failure in the Orange Cab, Alfetta GT. It uses a twin Spark engine that seems to have an inherent fault that other Alfa donks don't. It is the crankshaft to camshaft chain drive sprocket assembly. The fault lies in the spindle that only has a press fit into the large sprocket. Once it lets go, crank and valve timing flies out the window and you have a set of bent valves like me. Just beautiful.

See photo for details

Hi Mike, the only time I have come across this is when there was an underlying problem/cause. In the case I’m aware of it was a cam bearing cap being installed 180deg out and after a short drive and up to temp it quickly seized the cam and caused a similar issue. Although luckily just at the right time that no valves were bent.
Which leads me to.. has anyone had the cam caps off recently? Are/were they installed correctly? do the cams turn freely... when hot? hard to check but possible. Is there any markings in the cam bores that might indicate one has grabbed? (maybe a Dowl sleeve missing causing mis alignment?)
Only other scenario that I’ve come across (although not an nord/TS engine but a supercharged engine) is hi revving a tight spec engine when cold. The extra combustion temp caused by the forced induction can heat the exhaust valve quicker than the rest of the head and then it expands and Momentarily seizes in the valve guide, essentially stalling the cam causing excessive strain on the drive components of the valve train.

Well my situation is a lot simpler and it pertains to two exact same situations and only ever involving the 8v Alfa twin spark engines. One was a 200hp NA engine and the present one a supercharged one. Both developed this exact same problem due to the movement of the chain sprocket on the shaft causing a valve timing clash. There is no evidence of cam follower or cam bearing seizures/grabs. Not to say I do not agree with you but my results point to the same factory foul up. It has only affected the inlet valves as far as I can tell without the head being off at this stage.

Never experienced this with a 105 or 116 engine from the same cause. Solution. In future, replace the component from one of these. Bulletproof.

Some thoughts from Vin Sharp on this:

Er, yes a poor design idea particularly when they previously keyed them on all models for 30 years. In theory the interference fit should do the job, but that assumes all manufacturing diameters & bores are correct fit & a large hole/small shaft combo don't come together...
I've not personally seen one come loose yet, but have pinned a couple between the pairs just in case.
The sprockets & shaft appear to be steel & I've used a 4mm dia hardened steel pin to key it in place. This should be sufficient to stop it potentially working loose on the shaft. In both cases I did a test press (in the removal direction) to check that the pair were at least secured well before even bothering to attempt pinning. DON'T block off the oil supply thru the centre of the shaft when pinning!
PS, T/Spark are closer on the chains centre-line spacing, so you can't just toss in in a Nord one unless you can press it apart & machine a face to narrow it.

Good news. Got a replacement for the chain sprocket drive. I will install this once I get around to dismantling the engine. As you can see it has the cure-a keyway !!

Back on topic and more good news. 75 Evo located some couplings and bolts ASAP. Thanks good buddy. I asked him to hold off until I have a last minute door knock around here mainly due to current exchange rates and US postal charges.

Luckily I managed hold up Richard Andersen from Avanti Spares by the ankles and give him a good shake. To my surprise a pair of V6 couplings fell out of his pockets. How lucky can you get ?! I did get lucky 'cause nothing else fell out just in case yuz woz hoping JK.

With a bit more stuffing around I also managed to get some bolts from a mate who I remembered had some 15 years ago..and he still had 'em !!!

Thanks all round to the silent throng out there who have been fearlessly rummaging the Alfa junk pile in the garage corner to help out.

A few more small refinements around the rear suspension .

A closer view. (the site is playing up for posting stuff)

Back on engines..
Unlike the Greekster's tool, my head pushing tool seems to be working a treat. Got good separation already just after a couple of hours including set up that has left the head stud "wells" with enough recess to allow a good dose of penetrating fluid to form a reservoir. I will leave it soaking overnight and push the balance of the way off tomorrow.

Hey MD,

What's the bolt patterns for your wheels? Is it 5x100mm? Looks like it's redrilled, longer studs and a 10mm spacer fitted

Hi Zeefa,

What you are looking at is a PCD conversion to 114.3, 68mm bore, 5 studs.

Cheers.

G’day MD,

Thanks but what about your front hub conversion. Would like to see that as well. 5x114.3 is a very smart move.

As a special Easter consideration for you Big Guy, here are details of the front hubs.
The reason for the long bolts at the rear is to fix the brake rotor to the rear of the hub.

I was hoping to have the cylinder head off by now and it has moved about two thirds of the way off, however the rest is really bound up solid so I am taking it quietly and applying penetrating fluids while I am waiting to have the pulling plate modified for the Alfetta head. When it arrives, I will apply both a push and pulling technique at the same time to remove this really stubborn cylinder head.

Cheers

Hi Md , good to see you making progress . Work is always exceptional as usual despite having to fight off the lovely Gold Coast weather !
A few questions if you don’t mind . Are you leaving the camber on rear as standard ?, have you ever had the stud bolts ripping out the spacer ? Reason asking about that as I know you’re paranoid about safety but I have seen a failure on my mate up the roads Porsche 944 track car. The spacer was about 25mm thick so I was surprised to see it take a whole chunk out . Thinking about it it could only happen if the wheels were not tight or there was wear around the studs, maybe even the hub locator was not perfect .
Ok moving along.
Great idea for holding the spring down. What are those spring rates for that roughly in kg/cm ?
I see your using the upside down ball joints on front A arms. I do realise this is specific for a track car with limited travel other wise the lower A arm binds on the stub axle.This you mentioned a few years ago. Which ball joint are you using and roughly how much travel you aiming for ? . My mate here with the black 75 is using cnc pins machined into the A arm with spherical bearings to give a little more room for travel but that is quite a major process.
So now I’m bombarding you with lots of questions. Are you designing your set up with 16” or 17” rims ?
So otherwise how’s things holding up ?

Hi Kevin,
Making incremental progress given the global slow up of everything.. anyhow I will answer your questions as you requested:-

1 Please look carefully at the hub conversion mounts. They are not the conventional spacers. The rear studs are held captive by the original hub therefor there is no difference in the structural strength from the original. The fronts are rear fitted to the conversion plate using the highest grade aluminium available. Time will tell.
2 The rear camber is already set for 2.5* -ve
3 Spring rates are 600lb front and 285lb rear-you do the maths
4 Expected travel 35-40mm
5 Rim size is 16"x7.5 x 50 -ve offset.

EUREKA ,it's OFF !!

After 4 days of struggle with that darn head it is finally off the block.
It took the use of a double puller system to force the head off plus using some drastic stuff like mild phosphoric acid in the stud wells to react with the minerals binding up the rods with the head. In the end, the majority of any anti seize solutions had a minimal effect because it just could not flow to where it was needed.

The initial separation was relatively quick and easy BUT THEN, things got bloody tight.

Let me tell you folks if you do not make your own coolant from a concentrate and your own KNOWN distilled water, you are heading for a fall down the track when it comes to stripping your motor down. I can hear it now, oh but I use ready mixed coolant off the shelf. Well it might be convenient and it will do the job of anti corrosion and antifreeze but how sure are you that the solution is not made using tap water full of minerals which it is required to be for human consumption. It's the minerals that come out of solution (premixed or otherwise) that cause all the problems.

I say again, MAKE YOUR OWN !!

Here are the highlights from the idiot that used this engine who had no idea what proper coolant is.