Yes, I’ve been slack.

August 11th, 2013

But there is some small progress. Body bashing continues and I am getting there. Very slowly. I have also started thinking about the engine and what I will do there. My aim is to supercharge it so I have been thinking about that. A nice downdraft 1 1/4 inch SU came up on TardMe so I  grabbed it. It’s the only one I have ever seen on there and I think they are fairly rare but for what I have in mind it’s perfect.

IMG_4115_1 1 1/4 inch SU downdraft.

I think I previously mentioned I have a AMR300 blower (also off Trademe). This is a little supercharger used on the 3 cylinder Japanese Kei cars. The common ones are off Subarus. Mine however seems to be off a Mitsubishi. I’ve not found any mention of these online but they seem to be a variant of the AMR300 used on the Subarus. I bought a new V belt pulley for the blower from a nice chap in Australia at as mine didn’t come with one. When it arrived though I found it didn’t fit! I contacted the seller and he was the one who told me this was a rare version of the blower and what it was off. All of the ones he sells are the other kind. He sells the blowers, pulleys and manifolds if anyone else is looking for them.

It turns out the Mitsi variant of the AMR300 has a different shaft, mine being a taper and a 10mm nut instead of a straight 15mm keys one. So I need a different pulley. The body of the blower also has less mounting lugs than the Subaru ones. Now I do have a lathe so I should really be able to make up my own pulley.

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AMR300 with tapered shaft and single mounting lug.

My plan so far is to mount the blower high up above the head on the left hand side off the engine. To drive it I will use a belt off the cam pulley driving a jackshaft. The jackshaft runs back along the engine to another pulley that then has a belt going up to the supercharger. The jackshaft allows me to do two things. First since the cam pulley is only turning at half engine speed and I need the blower going at something like 1.7x crank speed I can mess with the ratios to get the speed I need. Trying to drive the blower direct off the cam drive would requite a massive pulley on the cam and a tiny one on the blower. It also take the drive back since I need to mount the blower with the pulley at the back of the engine. This is because the cam is gear driven so it rotates in the opposite direction to the crank. The crank goes clockwise from the front (I think?) and I believe the blower also needs to turn clockwise. So with the blower belt at the back it should all be going the right way around. Or something? I am still working all this out!

Since I am using the tall radiator I have a lot of height above the engine unlike the Ulster wannabes who chop their radiator surrounds down. The downdraft carb can be mounted directly to the top of the blower with a suitable short manifold (which I would like to cast if I can find time to get back into casting aluminium).

IMG_4118_1 Downdraft carburetor above blower.

In the pic above the front of the car would be on the left. The throttle linkage would almost be a direct link in this position. I would remove the mechanical fuel pump and use an electric one so the left side of the engine is clean and there is space to mount the gubbins. I would need a manifold coming down from the bottom of the blower into the head and need space on it to mount a pressure relief valve. Then the exhaust can come out and exit below all that. Everything should fit under the bonnet, no messy holes or bumps needed in the side of the bonnet. Everything seems to me to fit neatly and simply in place.

I have no idea if any of this is feasible but it’s a start.

As for the body the bashing on that continues. I am working on the right front corner now, the longest weld. And the most wonky since we did some bashing to get it to fit over the frame there. I am slowly getting there. Ont thing about doing all this is you learn not to be afraid of the file. It takes constant filing to see how flat the metal is and at first I was worried about removing too much material. But below you can see how much metal is removed after several hours work. There is a light sprinkling on the ground under the car and swept up it makes a tiny pile in my hand. The skin is being hammered flat, not filed flat. Also I used 1.6mm aluminium. I think even trying it would take me a long time to file through it!

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So work on the skin continues. Here are more photos of it as it is now.

IMG_4101_1 IMG_4102_1

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The other thing we did was mount the radiator just to fill the howl in the front so see what it looks like.

IMG_4111_1 Tall radiator.

Am getting there slowly.

4 Responses to “Yes, I’ve been slack.”

  1. emmanuel Says:

    Can you say if the SU downdraught carburettor you are using before the blower is an original Austin item?
    I have one here and I’m looking to see what vehicle it came from?
    Looking forward to your reply.
    Best regards

  2. admin Says:

    No, it wouldn’t be. I don’t think any Austin 7 was fitted with an SU originally. They were all added later as people built specials or wanted more power I guess. I think they were originally fitted to MG M-type midgets?

  3. emmanuel Says:

    Thank you for the reply – I only just accidentally noticed! (Did not receive any notification of a reply).
    I have yet to uncover the mysterious vehicle make & model this down draft was fitted to..
    Thank you for the info though!
    Best regards

  4. emmanuel Says:

    Happy New Year by the way!

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