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Piston orientation in 3.4 liter engine
Semi stupid question here. The pistons in the Mahle 3.2-3.4 kit (PP98-010). Should they be installed with the laser etched part number towards the flywheel side or the front side of the engine?
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05-21-2024, 11:42 AM
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intake valve relief up
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05-21-2024, 12:35 PM
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I think the valve reliefs are the same size
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05-21-2024, 02:16 PM
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05-21-2024, 03:34 PM
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PCA Member since 1988
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If the pistons have a space on one side, that goes under the spark plug. And remember, they will be opposite on the left and right banks.
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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05-21-2024, 05:27 PM
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What Peter said:
One side of the crown of PP98 is lower to accommodate the plug. Look at your heads to see which side the plug angles in from (they are not perpendicular to the piston top) and the part number /low side goes that way. If I recall correctly, that means the part numbers go towards the rear of the car if the engine were in (engine front) on bank 1-2-3, and towards the front of the car if the engine were in (flywheel side) on bank 4-5-6. 
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05-22-2024, 05:00 AM
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Just to be clear the pistons are installed opposite from one side to the other. On the 123 bank the numbers go to the front (fan side) of the engine and on the 456 bank the numbers go to the flywheel side.
That is what I thought but someone adamantly told me the numbers go towards the flywheel on both sides. Glad I checked. |
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05-22-2024, 11:50 AM
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I installed a set of these recently and I should recall and as logic would dictate, and as has been stated, low side of dome for the plug. With this build we also installed a set of Dougherty cams, Wong chip and headers, (street car). Not that the stock 3.2 was wimpy but what a transformation. Customer asked why didn't the factory so this. Well 1987 was a galaxy far far away. Bob
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05-23-2024, 07:07 AM
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As stated above, most combustion volume below the spark plug side.
Don't forget to check your ring gaps. My last new set of PP98-010 required adjustment. Mahle use to do that for you but no more.
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06-07-2024, 06:31 AM
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On must ALWAYS check ring gaps.
Cheers
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06-07-2024, 06:33 PM
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WYDBODY
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