Joined: Aug 2017 Posts: 369 Threads: 16
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8 Location: Port Elizabeth, Sunny South Africa
Car type: '26 Chummy, '28 Top Hat, '33 Type "65", single seaters
The modified front axle was copied off the Green Job which has a chassis number that dates as 1926, I'd guess it started off life as a Chummy and was built into its current singleseater firm circa 1949. There is a second such car around, the sister car to ours actually. Both have the same upside down front axles. Back in the day they cut a second axle to get the necessary extensions to weld onto the axle so as to get the 'drop' they wanted.
When we decided to build the Blue Job we thought about copying the Works tubular axle, but lack of a milling machine at home meant that we hit our first obstacle. So we decided to copy the one on the Green Job. Not wanting to cut up a second axle we asked my talented engineering friend Steven to fabricate suitable extensions to carry the front spring. He made these out of old two liter Alfa conrod little ends. We fabricated the the radius rods to suit the new axle. I suppose one day I'll look at machining a tubular front axle for it, but to be honest I've got a heap of other projects in the queue.... I think I'd rather rebuild the '28 R Type Top Hat saloon....
The trailer was another of Steven's designs, tows like a dream. Was designed to tow an Alfa Giulia race car. The mudguards are mine, every trailer I've ever dealt with has cracked or broken mudguards, I used a worn out Goodyear Wrangler commercial tyre out of the scrap bin at my local tyre place. cut the sidewalks out with a craft knife, cutting the steel belt casing in half was a bit more challenging. It was worth it as in 16 years I've never had to replace a mudguard. I broke a bracket clipping a fence, but that was my fault....
After several years of building early Alfa Giulietta's, it's been really fun to get back into Austin Sevens again.
Joined: Aug 2017 Posts: 369 Threads: 16
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8 Location: Port Elizabeth, Sunny South Africa
Car type: '26 Chummy, '28 Top Hat, '33 Type "65", single seaters
12-12-2018, 10:04 PM (This post was last modified: 12-12-2018, 10:12 PM by Greig Smith.)
Well it's time for an update on the blown Seven, after the post Simola Hillclimb engine rebuild, things went into a holding pattern for a while as we prepped three of our Giulietta Alfa's for a Tour out here. In the final stages of getting ready for the Tour I got a call from Mark Woolley from the Speedstream Group (www.speedstreamgroup.com) , they were planning a re-enactment of the 1934 Grand prix in East London, South Africa and one of the cars that participated in those early South African Grand Prix was a Works Rubber Duck driven by Major Doug van Riet - some details here --> https://www.motorsportmagazine.com/archi...correction
Sadly this car has left our shores and Mark asked if we would be willing to bring our singleseater to 'represent' the Austin entry - OK, Mark, but which singleseater do you want ? Bring both was the reply... so we did.
Both Sevens were prepped, both cars needed manifold work, the Green Job had a crack in the banana's and the Blue job a warped flange - in theory this needed skimming, but the flange is already thin and I didn't want to remove any metal, so I bolted it to the heavy steel plate I use for making manifolds and heated it up with a large propane torch, when it was properly hot I walloped the back of the heavy steel plate with a large hammer to 'shock' the manifold pipes into taking a new 'set' before allowing it to air cool. Success & the flange is now perfectly straight. We've learned to think outside the box while building this little car.
Some final little details were sorted out, Mum stitched up some modifications to the seat cushions and a pad for my right knee, then we set off the 200 miles up the coast to East London. The event was spectacular, the 1934 winning Maserati was there, along with two ERA's, a K3MG, Alfa P3 Monoposto, two pre-war Aston Martins, a variety of blown MG's, two Bugatti's, two Riley's all representing cars that raced on the old Prince George circuit between 1934 and 1939 - more details here--> https://sahistoricgp.com/pages/about. We're on the very back row of the grid in this picture --> https://sahistoricgp.com/blogs/cars/emot...ast-london, I tried to get the Sevens to the front but there was something about that winning '34 Maserati..... . Another nice touch is that Whitney Straight's daughter, Camilla Bowater and her husband Michael, came out for the event.
Well to be mixing it up on the track with all those other cars was amazing, but to be there having fun with Dad was the best thing. For those who are really itching to ask, yes the blown car goes really well, at one point during the Saturday practice Dad was doing 55 mph when I passed him powering over 75mph on the short back straight... before the head gasket cried enough... So we parked it for Saturday night & went to dinner with the rest of the drivers. Arrived at the pits early on Sunday, whipped the head off, stuck the new gasket in with lashings of STAG jointing paste (for steam pipes) and torqued it down to 40lbs (The old one had been at 30lbs). I kept the revs down a bit for the 2 races and the parade on Sundays and she behaved like an angel. A pair of solid copper gaskets is being manufactured at the moment and as soon as they are ready, I'll change the current glued-in-there-with STAG-paste-one for a solid copper job. Oh yes, the blower does scream rather nicely when you wind the rubber band up a bit
A big "Thank You" to Mark Wooley & the Speedstream Team for making the event happen
Aye Greig
We were allowed to run an 11.5 mile section of the original Prince George Racing Circuit (now public roads) without our racing gear on - we were behind a police escort, hence the pictures of us on the grid in T shirts and shorts..... summer in Africa can get warm
Here's another pic of the 2 cars on the trailer. It always get a response on the road and when we roll up at an event. In practice the 2 cars are so evenly balanced on the trailer that I can hitch and unhitch it with them both loaded. I had to cut the top bar out the tailgate and stick the Blue Job's back wheels up onto thick timber planks to clear the tailgate - when we went to Simola in May I left the tailgate behind and taped the number plate onto the trailer, but I wanted to display the chevron board for safety, hence the dragster look of the Blue Job with the back end up a bit.
Joined: Aug 2017 Posts: 369 Threads: 16
Reputation:
8 Location: Port Elizabeth, Sunny South Africa
Car type: '26 Chummy, '28 Top Hat, '33 Type "65", single seaters
Joined: Aug 2017 Posts: 369 Threads: 16
Reputation:
8 Location: Port Elizabeth, Sunny South Africa
Car type: '26 Chummy, '28 Top Hat, '33 Type "65", single seaters
The standard copper-asbestos-copper head gasket can't cope with the blower pressure, even at a relatively modest 5 to 6 psi, so a purpose made copper gasket is being manufactured locally. Fortunately Dad had packed in a spare gasket, so we were still able to run in the historic Grand Prix events on the Sunday. As you can see, I did a proper job on blowing the gasket...... the gap is about 3/8ths
On the subject of gaskets, we were wondering if its worth up-sizing the head studs from 5/16ths to 3/8ths (8mm to 10mm) ??? Anyone have any sage advice here ???
Tasks before the Simola Hill climb - need to add a blow-off valve to the intake manifold + a pipe to the supercharger pressure gauge
You could try dry decking it or use a fine wire as they do in the US to stop the gasket creeping.Austins went from 14 to 24 then 32 stud heads for the same reason I'd guess. The two above the inlet ports do very little as the're only pulling the face together.
Great photo's you've posted Greig.
HI Greig,
Thanks for the update and photos,
Regarding going to 3/8 or 10mm studs probably a good idea they will provide a bigger thread area for grip in the head
especially when you start upping the boost and the blowoff valve will be a must as you have a direct drive to the blower.
Keep up the great work and enjoy your Self
All the best for Xmas and the new year
I would regularly blow head gaskets in the Fiat I turbocharged in the 80's. Made a solid copper gasket with copper wire "O-rings". The gasket never failed so I could progress to breaking more expensive engine bits rather than blowing the gasket!
I would recommend Blow off valve first - solid head gasket second.
of course the good thing about a solid gasket is you can make it thicker and take a bit off the compression ratio.
The event does look like it would have been a fantastic experience. Just reward for all the effort you put in to putting the cars together.
. Another nice touch is that Whitney Straight's daughter, Camilla Bowater and her husband Michael, came out for the event.
