Arnott Supercharger rebuild

[dchw1975]

Hi,

For a bit of fun I bought a disassembled Arnott supercharger that I want to rebuild back to running condition of suitable size for an A7. Does anyone have and diagrams or pictures of the innards of an operation one that I can use for reference please?

Cheers

David

[mk1-mark]

The Arnott blower is very simple indeed, it just has 4 Tuffnol blades that are held against the blower wall by centrifugal force.  As long as the blades are a good fit in the rotor slots, the bearings at either end are good and it has a small constant loss oil supply it can't really go wrong.

There is a lot of good info here.

https://www.mg-cars.org.uk/mgtd/mgtd_acc...argers.htm

[Zetomagneto]

Mark, You have clearly have not seen inside a proper original Arnott.
They are more along the lines of a Shorrock.

[mk1-mark]

Whoops, I stand corrected.

I have only had 1 blower that I understood was an Arnott, that was as described above.  I have however built & used a few Shorrocks.  These ARE NOT straight forward.

Sorry for the misleading post above.

---

I was getting my Arnotts & my Judsons muddled up.

As I say, sorry for the duff post above.

[Zetomagneto]

I have rebuilt 2 Arnotts, they are very time consuming there are no spares so anything you need has to be made

[dchw1975]

Oh joy

I don;t mind making things but need to know where I stand with an exploded diagram to star off with.

Cheers

David

[Ray White]

I couldn't help but notice that the advice is to lock the automatic advance and retard in the distributor. I am not questioning the advice but I would like to know the thinking behind it.

Thanks.

[Stuart Giles]

I couldn't help but notice that the advice is to lock the automatic advance and retard in the distributor.  I am not questioning the advice but I would like to know the thinking behind it.

Thanks.

When supercharged motors come "on boost" the real time burn of the air/fuel mixture stabilises or even decreases, so they tend not to need much or any further ignition advance. The last blown motor I  had on the dyno needed the centrifugal advance to be  shortened to 8° in order to have a reasonable timing setting at tickover. The total advance "all in" on this A7 motor occurred at about 3000 Revs.

Modern(ish) turbo motors which still have a conventional distributor often use an electronic "boost retarder" box which as the name implies retards the ignition timing when the motor comes on boost.

[Ray White]

I really appreciate your explanation.  There is much I don't know but I have at least learned something today. 

 Many thanks.