achris
More fish than mountain goat
- Joined
- May 19, 2004
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(EDIT: There is a parts list in last post of this thread)
There seems to be a lot of confusion around exhaust shutters for SBC and V6s I/Os.. (this also applies to most BBC as well).
From the start of the 'R' series and the new inner transom plate (1982), up to about 1995 the shutters used were the single plate on a shaft type. These worked well, until they didn't. Given enough time the tabs on the shutter that sit on the shaft would eventually wear though the shaft. If you're mildly unlucky the shutter will lodge in the bottom of the Y-pipe and eventually wear a hole through it. That will let water into the boat... Not good!. I know this from first-hand experience
Once Merc realised the problem with the old style shutter they redesigned them and the Y-pipe. The new Y-pipe is used from about 1996 (corresponds roughly with the advent of the Vortec heads). The new style shutters are a 2 piece 'clapper' design and the part number is -807166A1, with one notable exception, the 'batwing' (single piece) manifolds of the V6. It has a different Y-pipe and so a different shutter. The number for those shutters is -807166A2. By now we hope all batwings have been replaced with the more conventional 2 piece system. But the shutters remain the same, the A2 number. (unless the Y-pipe has also been changed in the conversion).
If you have a pre-96 engine and need to replace the shutters, they supersede to the new design and the number is -807166A3. It comes assembled with a carrier to fit straight onto the top of the old Y-pipe. When this shutter needs replacing, you use the same number.
So, in brief.
-807166A1... for new style (1996 and on) Y-pipe (except batwing V6s).
-807166A2... for batwing V6 manifolded engines. Or ones that have been converted, but still have the original Y-pipe.
-807166A3... replacement for all old style (1982-1995) shutters. Use this number when replacing them too.
Chris...
(At the bottom of this thread is a new post with all the part numbers, and what you need if you plan on converting to dry-joint exhausts.)
The difference between 'wet joint' and 'dry joint' exhaust systems explained.
Line drawing of the old and new style shutters.
There seems to be a lot of confusion around exhaust shutters for SBC and V6s I/Os.. (this also applies to most BBC as well).
From the start of the 'R' series and the new inner transom plate (1982), up to about 1995 the shutters used were the single plate on a shaft type. These worked well, until they didn't. Given enough time the tabs on the shutter that sit on the shaft would eventually wear though the shaft. If you're mildly unlucky the shutter will lodge in the bottom of the Y-pipe and eventually wear a hole through it. That will let water into the boat... Not good!. I know this from first-hand experience
Once Merc realised the problem with the old style shutter they redesigned them and the Y-pipe. The new Y-pipe is used from about 1996 (corresponds roughly with the advent of the Vortec heads). The new style shutters are a 2 piece 'clapper' design and the part number is -807166A1, with one notable exception, the 'batwing' (single piece) manifolds of the V6. It has a different Y-pipe and so a different shutter. The number for those shutters is -807166A2. By now we hope all batwings have been replaced with the more conventional 2 piece system. But the shutters remain the same, the A2 number. (unless the Y-pipe has also been changed in the conversion).
If you have a pre-96 engine and need to replace the shutters, they supersede to the new design and the number is -807166A3. It comes assembled with a carrier to fit straight onto the top of the old Y-pipe. When this shutter needs replacing, you use the same number.
So, in brief.
-807166A1... for new style (1996 and on) Y-pipe (except batwing V6s).
-807166A2... for batwing V6 manifolded engines. Or ones that have been converted, but still have the original Y-pipe.
-807166A3... replacement for all old style (1982-1995) shutters. Use this number when replacing them too.
Chris...
(At the bottom of this thread is a new post with all the part numbers, and what you need if you plan on converting to dry-joint exhausts.)
The difference between 'wet joint' and 'dry joint' exhaust systems explained.
Line drawing of the old and new style shutters.
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