Bosses - who needs more?
 

The early sandcast aluminum cases had bosses for where the chain ramp pins go in.

http://forums.pelicanparts.com/uploa...1252043338.jpg

By 1976 (if not at the start of the pressure casting regime) some extra bosses appeared in this area, along with the previous ones. Just not drilled or tapped.

http://forums.pelicanparts.com/uploa...1252043414.jpg

I finally got around to taking pictures, after years of wondering what these extras might be for. Was Porsche still in doubt as to where the ramps ought to be? Were these for some Sportomatic equipment?

Inquiring minds want to know.

Walt Fricke

I think there might have been some smog equipment air pumps there?

I know the 930/911SC/Carrera Aluminum cases had mysterious bosses which turned out to be used for a gear-drive system for the cams. It was only used on the Porsche Flug Motor and the 956/962 engines.

The smog stuff went on the upper left side of the left chain housing and housing cover. That's why there are a pair of 8mm studs up there holding the cover on, instead of the 6mms for the rest of the cover fasteners.

Gear drive for the airplane motors sounds promising. I didn't know that the 956/962 engines had gear drives. At least that would be bilateral.

Walt

956 gear drive
 

Thanks, JC

Fascinating. Injectors pointing upstream at the butterfly!

Nothing obvious about how those extra bosses would relate to that single gear more or less centered in the case housing to either side of the centerline, though. Maybe a plate with a shaft sticking out to hold the gear?

Walt

Walt - a couple of pics from the "rebuilding a 962 motor" thread
http://forums.pelicanparts.com/911-engine-rebuilding-forum/248909-rebuilding-962-motor.html#post2208551

Block casting is 930.101.103.6R

Each boss shows a bolt head - but I can't see directly how the bosses are related to the gear drive. You can see the location of the gear bearing journals....

Sorry this doesn't appear to answer your question

http://forums.pelicanparts.com/uploa...1252361004.jpg
http://forums.pelicanparts.com/uploa...1252361168.jpg