|
Author |
Message |
Nick57
Joined: 09 Dec 2013 Posts: 35 Location: Leicestershire
|
Posted: Thu Jun 26, 2014 7:24 am Post subject: Corroded SU Carbs |
|
|
I have a pair of 1930s 7/8th bore SU carbs that are totally seized. Pistons, jet and butterfly all seized solid.
I have tried penertrating oil, leaving in a bath of diesel for several months without sucess.
Anybody have any ideas on getting them apart without causing damage to them as I think with care they could still be useable.
Nick _________________ Current Riley 9 Peugeot 505 Moto Morini 350
Have owned Aston Martin Inter Rudge Ulster Renault 4 Rover 100 Austin 7 Aston Martin Le mans |
|
Back to top |
|
|
Rick Site Admin
Joined: 27 Apr 2005 Posts: 22452 Location: UK
|
|
Back to top |
|
|
Nick57
Joined: 09 Dec 2013 Posts: 35 Location: Leicestershire
|
Posted: Thu Jun 26, 2014 10:35 am Post subject: |
|
|
Thanks Rick.
I will give it a try and report back.
Nick _________________ Current Riley 9 Peugeot 505 Moto Morini 350
Have owned Aston Martin Inter Rudge Ulster Renault 4 Rover 100 Austin 7 Aston Martin Le mans |
|
Back to top |
|
|
Jim.Walker
Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield
|
Posted: Thu Jun 26, 2014 12:17 pm Post subject: |
|
|
In a working SU carb there is an inevitable air leakage past the piston. If there is anything such as pitting or corrosion on the cylinder walls or piston edges their operation will be unsatisfactory.
The test is to push the piston right into the cylinder, invert it and holding the piston,spin the cylinder until it falls off under gravity. From memory there should be no metallic noise and the "spin off" period should be about 3 to 4 seconds. I would not expect units which have been seized to pass the test though.
Any quicker and the unit will not work satisfactorily.
Of course that does not apply to the early "bellows" types which are closer in operating principle to Stromberg CDs. As they say "there is nothing new........................................."
Jim. _________________ Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then! |
|
Back to top |
|
|
aps
Joined: 15 Mar 2013 Posts: 37 Location: aberdeenshire
|
Posted: Fri Jun 27, 2014 9:49 pm Post subject: |
|
|
i may have a pair of reconditioned su,s im currently clearing out one of my workshops ,i know i have them when i come across them your more than welcome to them rather than dump them ,wayne |
|
Back to top |
|
|
baconsdozen
Joined: 03 Dec 2007 Posts: 1119 Location: Under the car.
|
|
Back to top |
|
|
Nick57
Joined: 09 Dec 2013 Posts: 35 Location: Leicestershire
|
Posted: Thu Jul 10, 2014 7:06 pm Post subject: |
|
|
10 days in Coca Cola did clean up some of body casing and the brass, but sadly still unable to dismantle carbs.
I will give the vinegar a try.
I know that heat usually works, prehaps 20 mins at gas mark 6 when Mrs N is out might do the job.
Nick _________________ Current Riley 9 Peugeot 505 Moto Morini 350
Have owned Aston Martin Inter Rudge Ulster Renault 4 Rover 100 Austin 7 Aston Martin Le mans |
|
Back to top |
|
|
Old Wrench
Joined: 23 Dec 2013 Posts: 226 Location: Essex and France
|
Posted: Fri Jul 11, 2014 9:42 am Post subject: |
|
|
The early 1930s SU carbs were mainly constructed from sand cast ally.
The verdigris will mainly be Corundum: sadly, one of the hardest substances known to man! Think Aluminium Oxide abrasives!
Corundum will dissolve in acid: I would probably try a 10% solution of Hydrochloric Acid, used as a warmish bath and keep checking to ensure not too much of the parent metal becomes eroded.
The jets and jet carriers are of course, brass and since brass is made from Copper and Zinc and as Zinc is the softer and most reactive metal, the process of "De-Zincification" means Zinc molecules sort of corrode out.
Judicious application of local heat should allow removal (since the relative rates of liner expansion means the ally housing expands faster than the brass) and thereafter use Phosphoric Acid, carefully, to clean (e.g. Jenolite simple liquid).
After cleaning brass using phosphoric acid the surface will "Pink Up", not a problem as it will soon go.
BTW: seems two carbs like this are worth quite a bit of cash! |
|
Back to top |
|
|
roverdriver
Joined: 18 Oct 2008 Posts: 1210 Location: 100 miles from Melbourne, Victoria, Australia
|
Posted: Fri Jul 11, 2014 11:39 am Post subject: |
|
|
The mix that I use for 'unsticking' rusted items like nuts, bolts studs etc., is a 50/50 mix of acetone and ATF. The acetone thins down the ATF so that it penetrates into the bonded area. I have used it on steel bolts into aluminium castings, but have never tried it aluminium to aluminium.
It does have the advantage of being a non corrosive lubricant rather than something that could etch away the surfaces. _________________ Dane- roverdriver but not a Viking. |
|
Back to top |
|
|
petermeachem
Joined: 23 Sep 2013 Posts: 358 Location: Chichester Sussex
|
Posted: Fri Jul 11, 2014 11:54 am Post subject: |
|
|
If Coca Cola worked a bit then stronger phosphoric acid might work better. I bought 5l of milkstone remover which is used in dairies: I used it for de-rusting purposes. It is much more concentrated than coke but not so much that it dissolves you. I'd dilute it somewhat and pull the carb out every hour to check nothing nasty was happening. |
|
Back to top |
|
|
Bitumen Boy
Joined: 26 Jan 2012 Posts: 1735 Location: Above the snow line in old Monmouthshire
|
Posted: Fri Jul 11, 2014 1:27 pm Post subject: |
|
|
petermeachem wrote: | I bought 5l of milkstone remover which is used in dairies: I used it for de-rusting purposes. It is much more concentrated than coke but not so much that it dissolves you. |
Maybe not, but I find it still stings like mad if I get it on my hands - you'll find that rubber gauntlets are a sound investment |
|
Back to top |
|
|
|