I've been the happy owner of a modified 911E since 2012, engine believed to be to S spec with hi comp pistons and a Bob Watson rolling road sheet (196bhp).
This rebuild was initiated by serious knocking noises from the engine in the middle of 2015. My immediate reaction was that I'd run a bigend, I had a huge amount of history which indicate that although the top end had been rebuilt to S spec 20000 miles ago the bottom end was untouched. A bit more digging found a in invoice for replacing main and big end bearings but over a hundred thousand miles ago. So a big end seemed a reasonable deduction.
The car sat around for a month or so, I knew it meant taking the whole thing apart and was reluctant to bite the bullet!
Then friends at Gantspeed offered me a corner of the workshop to strip the engine and provide guidance, taking over the rebuild when necessary.
So offer accepted and off we go.
Stripping the engine down a number of things became apparent, Crank and bearings were good so not a big end then. It did look as if at some point the cams/rockers had been starved of oil so there was obviously a problem somewhere. There was wear and tear in the valve gear and oil leaked from all over! Cleaning and measuring gave us an initial list of problems:
The timing chains and idler gear were worn out
The intermediate gear was worn and had suffered some surface damage.
The on-engine oil cooler leaked
Both cams were pitted and worn as were several of the rocker arms
Several rocker shafts were worn
The valve guides were worn
The little end bushes were worn and needed replacement
The valves and springs were sufficiently worn to need replacement
Some of the effected cams
Old and new sprockets for comparison
