For example, cylinder head bolts are called " bolts " ( at least in North American usage ) despite the fact that by some definitions they ought to be called " screws ".
22.
To further discourage its removal, the bolts securing the hardtop in place were changed to Torx " tamper proof " bolts, requiring special tools, in place of standard hex-head bolts.
23.
The intake manifold to head bolt pattern was redesigned to improve gasket integrity-four of the center intake manifold bolts were drilled at 72 degrees instead of 90 degrees for the cast iron cylinder heads.
24.
Owing to a large error in the factory head bolt torque specifications ( likely owing to switching away from using an asbestos head gasket in lieu of a copper one ), all of these engines had severe problems with blown head gaskets.
25.
This, along with hydraulic valve lifters which required no adjusting and special cylinder head gaskets which eliminated the need for periodic retorquing of the head bolts, made the 6.9 nearly maintenance-free for its first 50, 000 miles ( 80, 500 km ).
26.
This, along with hydraulic valve lifters which required no adjusting and special cylinder head gaskets which eliminated the need for periodic retorquing of the head bolts, made the 6.9 relatively easy to maintain and service for its first 50, 000 miles ( 80, 500 km ).
27.
The A279 initially used the B-block head bolt pattern, which " badly hampered " its exhaust ports, forcing the use of a serpentine flow around some of the outer bolts This was changed late in development, but not before some tooling based on the original design had already been created.
28.
The next iteration of the engine mated an improved head design to the 302 cu in block, producing the famous " Boss 302 . " The heads from the Boss 302 would become the production heads on the 335-Series Cleveland engines, which used the same bore spacing and head bolt configuration as the Windsor engines.
29.
Other important differences between the Vortec 8100 and older Big Blocks include a changed firing order ( 1-8-7-2-6-5-4-3 ), a new 18-bolt head bolt pattern, longer connecting rods, different symmetrical intake ports, different oil pan rails and the use of metric threads throughout the engine.
30.
There were several problems with these engines, including water and corrosion in the injectors ( no water separator in the fuel line ), paraffin clogging of fuel lines and filters in cold weather, reduced lubrication in the heads due to undersized oil galleys, head bolt failures, and the use of aluminum rockers and stanchions in the 4.3L V8 engines.
