Finished manifold.

April 19th, 2014

Today I finished welding up the manifold. Nothing too tricky really. I did tack weld it with the mIG first to make sure everything was in the right position although since I had already made all the holes the only thing I really had to get right was making sure the plenum and the outlet port flanges were at right angles. I tweaked things until they were then MIGed them in place then brazed around the welds hence the couple of bumps in the brazing!

IMG_1562_1 IMG_1564_1

That’s under the plenum though so not really visible. I soaked it all in caustic soda to remove the flux but it still needed a lot of wire brushing to remove it all. I then filed all the mounting flanges flat then sanded everything smooth. I’ll pressure test it all by bolting on flat plates and filling it with water then pressurising it with air from the compressor. It’s the same way I have tested model steam engine boilers. You fill it with water first since water isn’t compressible (much) so if it does burst you don’t have a sudden release of a massive volume of compressed air. Hopefully that should prove it’s solid enough. To test for leaks I can just blow air into it (at low pressure) and put it in a bucket of water and look for air bubbles.

I did a test mounting of everything and it looks good.

IMG_1566_1 IMG_1568_1

IMG_1574_1 IMG_1579_1


The lugs on the blower also nicely mate up near some of the head studs so I can make an additional bracket to support the blower to the head via long studs.


With the downdraft SU on top there is about an inch clearance to the bonnet line. I’ll need maybe half an inch to make an adapter plate to bolt the carb to the blower so the bonnet will need a tidy little bulge right above the carb I think.

Next, back onto aluminium bashing. Drilling and tapping the plenum for a vacuum/boost port won’t take long.


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