Pete wrote:
If you're going the Appendix K route, then modifying the bulkhead in any way is a big NO NO. I think you're right in that class D and other regs it doesn't matter because in theory you can cut the bulkhead to accept a Weber on long manifold.... could be wrong.
you can 'nibble' or better, 'bend' the bulkhead to get a weber in for class d, but as the hscc rules state that the bulkhead cannot be 'cut' its best not to hack it all out for a weber air box.......
if only I had read the rules all those years ago when I set about my car with a plasma cutter, it would have made my life so much easier now - it takes a lot more work to re-instate it, than it did to hack it out, that's for sure......
su_mark wrote:Somewhere deep in the archives, I have the original War time SU modifications book. In that book is an entry referring to the Rolls Royce Merlin Carburetter and the 'anti G device modification'. It is signed off by a certain Miss. Shilling.
Very cool (if you're me!)
the little washer that she thought up was such an elegant (and very simple and cheap) solution to the problems that Spitfires had of 'coughing' when in negative 'G', not only must it have saved many lives, it must have literally cost buttons to produce it
not often that can be said about a military procurement problem.
and all the poor lady got was endless piss taking from dirty minded blokes.......
she was actually pretty fierce in reality, raced motorbikes and cars and was involved in the post war bluestreak missile program
smithyrc30 wrote:When I was a callow youth doing my round robin on the job training as an apprentice for JRT (as it was back in those days) I did stint at the SU works in Erdington, specifically in the development department.
They had in the entrance hall a selection of carburetors charting the development of the SU fuel system (along with pumps and auto chokes) from the brass bodied right through to the latest fully electronic units then in development.
It was there I saw the DU for the first time. There was a 1 3/4 inch on a A series manifold and a pair of 1 3/4 (sectioned) on a dolomite sprint manifold. My memory is a little hazy on it but I recall they had run it on there engine dyno on a 1300 but it was too costly for Austin Morris at the time. JRT were all going fuel injection so no one was interested. The HIF series was out and doing the 'low speed economy' much better than the DU in single and twin format and cost a whole heap less to make (even when you had two). It was difficult to cast reliably and expensive to machine I was told. I think back in the files in storage in the UK I have one of the technical service brochures for it.
One of the guys there raced Mini 7 at the time (I bought some of his old bits for my 1275GT, a head and lightened flywheel) and he had done the running of it on the A series on the dyno. He said there really was not much difference between the Weber 45 and the DU and only a small improvement on the twin HS4 and twin HIF38 set up.
I cannot for the life of me remember his name. Bill something or other I think. This would have been 1981 or 1982.
Thats seriously interesting stuff smithyrc30. I should very much like to see a copy of the technical brochure you mention if ever you get the chance to dig it out!
There are several reports around and current DU users who testify to them being on par with the DCOE.
About a year ago, a friend of mine discovered a pile of DU6s in a barn. There was about six or eight of them, and he made a fortune on eBay, but before he flogged them off, I did a bit of investigating as it ticked my Stupid-enough-to-be-interesting box.
Speaking to Tim H, as well as SU/Burlen and having a good trawl of the interweb, I came to the conclusion that without major modifications internally, the DU6 would never make a good road carb. It would however, have been awesome on the rollers.
From what I remember, it has a cobbled together part-throttle bypass system which doesn't work very well, in addition to no choke. Let's not forget that it was designed for use on a race engine in racing conditions, where the throttle generally has two positions - WOT or shut.
If the repro's differ to the originals and work on a road car, I'll towards the front of the queue to get one.
Alex wrote:
From what I remember, it has a cobbled together part-throttle bypass system which doesn't work very well, in addition to no choke
The system employed on these carbs isn't a 'bypass' but a full throttle weakening device. Long story short. They were primarily designed to serve one cylinder of an engine with one choke of the carb. When this is the case, full throttle pulsations can become heavy tending to over enrich the mixture. So, tune the carb correctly at part throttle and the device kicks in at full throttle, leaning off the mixture. It works very well.
The new units have 'lugs' cast in to accept standard SU choke linkage if needed.
Heres a pair that I built while working at a Triumph restoration specialist - custom adapter to mount them to Weber manifolds, custom linkage and HIF44 dashpots and pistons if I remember correctly! For a historic TR3A racer. Appologies, you will have to zoom out!
1963 austin Cooper s mk1 1071
1966 Austin Cooper s mk1 1275
1968 Austin Cooper mk2 998
1962 Morris mini super 850
Porsche 997 turbo S
Ford transit van 280s.
su_mark wrote:Somewhere deep in the archives, I have the original War time SU modifications book. In that book is an entry referring to the Rolls Royce Merlin Carburetter and the 'anti G device modification'. It is signed off by a certain Miss. Shilling.
Very cool (if you're me!)
Slightly off topic, the RR Meteor engine was manufactured at the Morris Engines Coventry facility at Courthouse Green during WW2. The Meteor was the detuned Merlin without supercharger, used in Cromwell and other tanks. But Miss Shilling's orifice was probably not needed for the Meteor version...
I believe most (all?) of the Cooper S engines were also produced at Courthouse Green.
su_mark wrote:Somewhere deep in the archives, I have the original War time SU modifications book. In that book is an entry referring to the Rolls Royce Merlin Carburetter and the 'anti G device modification'. It is signed off by a certain Miss. Shilling.
Very cool (if you're me!)
Slightly off topic, the RR Meteor engine was manufactured at the Morris Engines Coventry facility at Courthouse Green during WW2. The Meteor was the detuned Merlin without supercharger, used in Cromwell and other tanks. But Miss Shilling's orifice was probably not needed for the Meteor version...
I believe most (all?) of the Cooper S engines were also produced at Courthouse Green.
Pulling negative G in a Centurian tank? By the time the Meteor was in production, the Merlin was probably on a pressure carb.
ivor badger 2 wrote:
Pulling negative G in a Centurian tank? By the time the Meteor was in production, the Merlin was probably on a pressure carb.
A close thing, Meteor production started 1st April 1943, the Bendix Stromberg and Rolls Royce pressure 'carburetor' were introduced during 1943. Exact date quite hard to find....
Alex wrote: ↑Sat Feb 25, 2023 6:39 pm
...that's one of the reasons I'm starting my Scrutineering & Eligibility training.
The playing field isn't level.
It never will be.
Depends if you are part of the 'circle jerk' or not, as to what you can run.
