Even more inlet manifold.

April 13th, 2014

Today I cut and shaped the little right angle inlet tubes. Joss noticed that my vice jaws were exactly the right height for one side of the inlet rectangle. So I just used the vice to squeeze the tube then a hammer to tidy up the corners. I eyeballed everything (measuring curved, round tube is hard!) and it came out fine.

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The rectangular ends fit into the holes I cut in the mounting flanges of course so they bolt to the block. They are a nice, tight fit.

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That’s the block I extracted these good tappets from being used for test fitting as it still has (long!) studs attached.

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Those tappets will be reground on the end to the correct radius for my cam.

I drilled some holes to match the inlet studs on a piece of flat steel bar so I can hold the inlets in the correct position once I start welding everything in place. But you can see how the inlets will fit into the bottom of the plenum here. The tubes will be cut down so the plenum won’t be so high as shown here. After a weekend of hand filing I couldn’t be bothered making the holes for the tubes. I need to go to the engineering shop soon so will buy the correct hole saw. It’s all made from pretty heavy steel. I am waiting for someone to suggest drilling holes in it to lighten it!

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I have also been working, on and off, on the horn I bought. We were trying to think of where were could get flat, spring steel to make a replacement spring. I was thinking piston ring compressors but Joss suggested these things:

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I popped down to the local panelbeating supply place and got some of them. You get four in a  pack and they are usually used for spreading body filler. I chopped and drilled one to make a replacement striker/spring piece. The steel isn’t as thick as the original so I made the metal weight on the spring smaller.

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I’ve been playing with replacing the electromechanical contacts with electronics and so assembled the horn so it was physically arranged how it was with the top spring contact but without worrying about all the electrical gubbins. Instead I am using a small circuit with a 555 timer and a MOSFET to electronically switch the coil directly. With a little tuning the thing is working. It makes a god awful noise. More a rattle/buzz than a beep. I realised I don’t actually know what a vintage horn like this should sound like. It’s not one of the Oogah ones. With the electronics you can tune it a little but it still sounds awful. I get a headache just imagining it now.

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I found a suitable tin to use as a temporary back cover. I should probably make something better or paint that one. But I kind of like the cows.

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