Monday, 19 May 2014

The head is on!

So we are all set. The sun is shining, I have a day free (after cutting the grass and making the family dinner) and I have all the parts, plus a very nice text from Bruce Longman via Draganfly with explicit instructions. Max is in bed, so he will be happy for a bit:

A Chocolate Sprocker, feeling very 'Sunday Morningish'
I have some high temperature silicone gasket as recommended by Bruce. Loctite say this is suitable for operating temperatures up to 275 degrees C (sustained) with excursions to 300 C:

So as recommended by Bruce, we start by laying a band of sealant around the pushrod tunnels, on both sides of the gasket. Actually easier to lay one bead on the gasket, and one bead on the block, making sure you have the handed gaskets the right way around:

No picture, but next I placed all the head nuts in position between the cylinder block fins, under their holes, with the flanges upward. Next, manoeuvre the head under the frame tube and drop it into place over the studs, making sure the extended, rounded ends of the studs drop into the nuts. Add the sleeve nuts inside the rocker boxes, and the 5/16" CEI reduced hex nuts outside the rocker boxes. You hand screw these down finger tight.

And as Kees Knegt pointed out in a comment to an earlier post, this would have been easier without the rockers! You cannot fit the pushrods with the rockers in place either (they don't slide sideways far enough) so I may as well have left them off... although I do like to trial fit everything at least once.

Next, with your thinnest 5/16" CEI open spanner, engage all the nuts on the downward facing head studs and turn them as far as they will go without using and force. You will realise now that if you leave one undone, and tighten the others, you will crack a fin by virtue of the loose nut pushing downward onto the fin below.

Once you have all the nuts finger tight you will see the head finally come down onto the gaskets. continue going around all the nuts inside & outside the rocker boxes until they are all snugged down finger tight.

You will need a variety of spanners to achieve this. The reduced hex nuts in the middle of the head, under the inlet tract are particularly inaccessible.

So, when everything is snugged down, use Bruce's torque figures and sequence to tighten down the head.

Job done.

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