Wednesday, 6 June 2018

More Cake

Another cake run today, this time out on the SQ4. The chain guard is not sorted and is going to need to come off again for some serious adjustment!

The weather was great though and the trip to Cley and back was uneventful, save to remind me what a lovely part of the world we live in. Here's the SQ4 enjoying a break at Glandford:


After a 24 mile round trip with no misfire, but rather slow (there is a lot of traffic around here in the summer) we have these results, taken with the engine running in the yard and measured immediately upon arrival:
  • 210°C on the fins near No.2 spark plug
  • 151°C on the inlet manifold flange - near the offside carburetter stud
  • 109°C on the carburetter flange, 1/2" from the 151°C measuring point but on the other side of the phenolic spacer. That's a 42°C differential across the spacer.
  • 87°C on the float bowl. This is much higher than usual and I think reflects the fact that the day was not windy and I was travelling rather slowly. There's more convected energy than I thought and I've decided that a heat shield may be in order
Whilst there was no misfire,  I think I could detect that the engine was not running as happily as before.

Ambient was around 23°C for most of the trip. I measured the other cylinder head temperatures as well and added them to my chart with some previous tests:


When I returned, I noticed a small leak from the oil tank cap. I'd given it an extra twist before I left in an attempt to seal it, so I'm sure the seal is not thick enough.

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