[412usa]

Dorien,

I took the opportunity to look at several pistons from two of my BS1 MkII
engines, which are based on the 100 series engines. Also I have included a
bit of history on Chassis 3020 (engine 219) to see if racers like Bill can
shed any light on the early history and the anomalies of two or three rings
in the same groove.

Engine 219, which was extensively raced had a huge 0.110 top compression
groove and was fitted with two or three rings (depending on the piston
number). This engine also had a very high compression which lead to failures
of the head gasket. I have been able to track down and talk to a number of
owners as far back as 1964, but the racing history is sketchy. Serge
Dermanian, who now runs the auto museum of Prince Rainier in Monaco, sold
the car from High Performance Cars in Waltham, Mass. but said the car really
belonged to Autolab Import (owned by Skip Barber) but had been sitting there
a while and so Peter Sacks (sp?) took the car to sell. Serge had fitted two
gaskets because the head had been milled so much. The previous owner, Albert
VanDam had said that the car was raced by a Greek mechanic called Makinon
(or Macadon) and a fellow called Felix Brossard. Serge said that Brossard
looked after Gaston Andrey's Birdcage Maserati. However, I have not been
able to confirm the ownership or any racing heritage. However, it might be
that during this time the top ring combination was installed.


Engine 294, which I don't think was raced, has the spec 0.093 top
compression groove. The specs for the pistons on both engines are as follows
(inches):

Engine BS1 Mk II 219: Piston 1.
Crown 2.582
Skirt non-thrust 2.588
Skirt thrust 2.596
Top compression groove 0.110
Second Compression groove 0.08
Third Compression groove 0.08
Oil scraper groove 0.156
Weight 234.9 g.

Engine BS1 MkII 294 Piston 4.
Crown 2.584
Skirt non-thrust 2.592
Skirt thrust 2.596
Top compression groove 0.093
Second Compression groove 0.08
Third Compression groove 0.08
Oil scraper groove 0.156
Weight 233.8 g.

Note that the pistons are oval and tapered to allow for expansion of the top
and non-thrust skirt at operating temperatures.

Best Wishes for the New Year to all.

Peter McGough