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I'm currently rebuilding a 1750 engine and thought it might be of interest for people to see inside the famous Alfa Twin Cam Nord engine. This is the all alloy unit which ran from the early 1950's until it's final Twin Spark incarnation in the 75 in the early 1990s.

It's quite an unusual design in that it is a "wet liner" engine. In effect the block is a box containing four seperate cylinder liners with coolant washing around the outside of them. This is great for two reasons - there is plenty of cooling and also when the bores are worn you can tap out the old liners and fit new ones. Another unusual feature are the cylinder head studs which run from the base of the block up past the liners and the head is lowered onto them. The cylinder head is then clamped down with nuts rather than the more common bolts you see these days.

Pic of block from above:


Can you see the four holes the liners press into? This creates a water tight seal to stop any coolant (hopefully!) from entering the sump underneath. The "box" on the right hand side is where all the timing gear and cam chains go.

From underneath (without sump):


From inlet side:


From exhaust side:


Lovely casting isn't it?!

This is a liner:

The tapered bit at the bottom is the bit which presses into the block and there is a (very!) thin rubber O ring at the top which makes the seal.

And here's a liner with a piston:


These are the rods all cleaned up, weighed and balanced to make the engine run as smoothly as possible. In fairness they were very closely matched to start with:



Here's the flywheel:

That's been lightened too (about 1.2 kgs) and balanced along with the clutch and the crank.

Here's an important bit! This is the crank. It is a five bearing crank which although common now was a rarity back in the 1950s and 60s - for instance many BMC and Ford engines of the day were just three bearing. The Alfa crank is immensely strong and very well made.

The crank has been balanced and the oil way plugs tapped and bolted which is a security measure to prevent the oil plugs coming lose at high revs resulting in oil pressure loss!



Last but not least, here's some ancilliary bits:

New oil pump. Took a bit of finding but Ebay came good in the end:


Clutch - yes, you read the name on the box correctly!! They're Italian and come very well recommended for fast road use:


Water pump:


Mechanical Fuel Pump:


That's it for the minute. I have a cylinder head and carbs ready (but no pics yet) and I'm undecided about the exhaust. I'll try and keep you posted as things move along - but don't hold your breath! Any questions, please stick them on here and I'll do my best to answer them.

PS Sorry for the lack of smilies but I've maxed the image allocation...
 
D

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That engine should be in art meseum. Alfa where always ahead of their time for everything. Even today.
 

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Lovely engine Rick - thanks for sharing. I wonder if it would hook up to a Sud transaxle? :D

Alfa engines have always been an engineering tour-de-force, witness the incredible lifespan of the Nord engine.

Now, if I could replicate the OSI Scarabeo transmission...

Lauren
 

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Nice Thread Rick, will pop back for an update from time to time.:thumbs:
 

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Great pics Rick and an informative piece too which is good for us non-engineering types. Thanks.:thumbs:
 

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Excellent attention to fine detail there mate.:): Similar to the 2006 Sprint, straight six? Did you say a dry sump?
However, my scrapped 'Puggy Wuggy', had separate liners, with paper gaskets at the bottom as opposed to synthetic rubber 'O' rings. Shss! No Puggie stuff allowed here, Zed!:D

Crank didn't need a re-grind then? Pain in the bum clearing the carborundum dust from the crank oil ways, after removing the hexagon socket plugs, and then locking them back in place.But worth the effort on the re-builds I did in the past.:): Keep it up mate, really good stuff, that brings back fond memories.:):
 

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Excellent attention to fine detail there mate.:): Similar to the 2006 Sprint, straight six? Did you say a dry sump?
However, my scrapped 'Puggy Wuggy', had separate liners, with paper gaskets at the bottom as opposed to synthetic rubber 'O' rings. Shss! No Puggie stuff allowed here, Zed!:D

Crank didn't need a re-grind then? Pain in the bum clearing the carborundum dust from the crank oil ways, after removing the hexagon socket plugs, and then locking them back in place.But worth the effort on the re-builds I did in the past.:): Keep it up mate, really good stuff, that brings back fond memories.:):
Hi ZF
It's a wet sump (which is a work of art in itself and I will post a pic when it's all cleaned up). I believe the old straight six was a very similar design to this, and yes Peugeot four cylinders were wet linered too!
The crank did need a regrind. I should have mentioned that. :eek:
Cheers
Rick
 

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Rick your the man!!!

Amazing stuff there, battling with my alfa here:( Its running but leaking oil(a couple of drops) and also some coolant:confused:

Thanks for the images, helps for newbie like myself to see the inner working parts:lol:
 

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Great stuff Rickie A.:): Really keen to view her as she progresses. The satisfaction factor is sublime with that sort of engineering you are at.

Beats Dyno's, Electronics, Induction systems, BHP's, of the shelf boxes, hands down(that comes later with Dynoscan?:D ) really class material there, keep it up.:):
 

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Really good and interesting stuff, Rick. You should host a 'building a twink' workshop - i'll supply the tea and bacon butties :)

lovely stuff - really enjoyed those pics, bud.

hope all's well matey,

g
 
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