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+--- Thread: Arnott Supercharger rebuild (/showthread.php?tid=2577)
Arnott Supercharger rebuild - dchw1975 - 28-03-2019
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
RE: Arnott Supercharger rebuild - mk1-mark - 29-03-2019
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_accessories_superchargers.htm
RE: Arnott Supercharger rebuild - Zetomagneto - 29-03-2019
Mark, You have clearly have not seen inside a proper original Arnott.
They are more along the lines of a Shorrock.
RE: Arnott Supercharger rebuild - mk1-mark - 29-03-2019
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.
RE: Arnott Supercharger rebuild - Zetomagneto - 29-03-2019
I have rebuilt 2 Arnotts, they are very time consuming there are no spares so anything you need has to be made
RE: Arnott Supercharger rebuild - dchw1975 - 29-03-2019
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
RE: Arnott Supercharger rebuild - Ray White - 30-03-2019
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.
RE: Arnott Supercharger rebuild - Stuart Giles - 30-03-2019
(30-03-2019, 12:59 AM)Ray White Wrote: 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.
RE: Arnott Supercharger rebuild - Ray White - 30-03-2019
I really appreciate your explanation. There is much I don't know but I have at least learned something today.
Many thanks.