Author Topic: mk1 compressions.  (Read 1973 times)

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Offline george sutton

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mk1 compressions.
« on: 16 May 2013 at 08:36 »
my 1947 engined mk1, was rebored and fitted with + 20 thou. oversize domed pistons couple of years ago. It has only run the equivalent of about 40 miles, but now lacks power, and is showing blue oil smoke.  It had new valves, and guides, and there is Definately No air leaks. magneto just completely rebuilt by D.lindsley. carbs are fine with new parts.  Question-- Ineed to do some compression testing.  therefore can someone tell me what sort of pressure i should expect to get , testing dry,ie, no fuel on, and cold ?   Ps. club piston rings were fitted with the required 0.006" gaps.  Denis.S
      Sorry, was'nt thinking when i put this on !  i should have realised that given the big piston clearences on the mk1. plus the large ring gaps , that,doing it cold ,not much pressure would register on a gauge anyway,     Have run up hot, whipped out the plugs, shove in the tester,and there it is !!   n/s lacking performance by 50%.  Think that those mk1. pistons with only two rings have suffered on running  in.  So, not much choice now ,except to hide from the wife for a while, and live in the tool box again.
« Last Edit: 23 May 2013 at 10:54 by george sutton »