WTF is this for?
01-28-2008, 02:49 PM
#21
Senior Member
Join Date: Jun 2004
Posts: 524
Originally Posted by RONIN FC' post='892056' date='Jan 11 2008, 08:08 PM
Ah! Now were getting somewhere!
Unused tension bolt hole. But it looks like it will run right through the intake runners...
Unused tension bolt hole. But it looks like it will run right through the intake runners...
Which is why they stopped using it.
Well, that is not entirely true. They stopped using it long before they relocated the intake ports higher for the FD. I was just thinking that maybe it was a 6-port thing, but I have seen pre 6-port era engines (first 6-port: 1981?) that also had that tension bolt hole blanked off.
01-29-2008, 11:08 PM
#22
Junior Member
Join Date: Oct 2006
Posts: 14
Originally Posted by heretic' post='892030' date='Jan 11 2008, 08:29 PM
Not just 13B but all models had an extra tension bolt hole.
If you look at the rear side housing there is probably an undrilled, unfaced boss at that location as well.
Mazda got a lot of life out of their casting forms. Notice that the RX-8 engine has rudimentary exhaust port depressions in the rotor housings.
If you look at the rear side housing there is probably an undrilled, unfaced boss at that location as well.
Mazda got a lot of life out of their casting forms. Notice that the RX-8 engine has rudimentary exhaust port depressions in the rotor housings.
Do you know if they are actually using the same casting forms?
I ask because there are differences between generations of housings.
01-30-2008, 03:09 PM
#23
Senior Member
Join Date: Jun 2004
Posts: 524
I am sure that they make minor changes here and there, but it appears that they only make alterations to existing designs instead of doing a clean sheet of paper setup every time. It looks like the rotor housings' innards are die-cast, so I wouldn't doubt it if they simply just changed plug position or whatever and then left everything else alone.
I think the last small block Chevy with a mechanical fuel pump was in '88 or '89. They kept right on casting the boss for it, and even machining and drilling/tapping the bolt holes in many cases, right up until the last of the Vortec 5.7l engines in '99 or thereabouts. It wasn't necessary but it also wasn't necessary to change it, so why change it?
I think the last small block Chevy with a mechanical fuel pump was in '88 or '89. They kept right on casting the boss for it, and even machining and drilling/tapping the bolt holes in many cases, right up until the last of the Vortec 5.7l engines in '99 or thereabouts. It wasn't necessary but it also wasn't necessary to change it, so why change it?
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