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Quench safety distance for a 496 MAG gen 7 BBC

General engine tech -- Drag Racing to Circle Track

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Quench safety distance for a 496 MAG gen 7 BBC

Post by koutroul » Sun Apr 14, 2019 3:00 pm

Hello I have a Mercruiser 496 Mag 375hp that has been bored over 030 inch to 4.280 and decked. The resulting quench varies and wanted to verify that using the original gaskets  will be ok and what is the minimal quench that I can have. I am using the Wiseco PTS524A3 pistons and K1 Technologies rods CH6700APRB8-A.
All 8 pistons are proud (above the deck) with following measurements:
Side A:
Side B:

Turner said he decked one side 010 mm and other side 020mm.

I think the genuine gasket is 0.051inches so if from 1.2954mm I subtract 0,27mm (max) I am left with 0.040 inches quench. The gasket is made to be used both with the standard pistons and the 030 over pistons that the manufacturer offers (however I am using Wiseco PTS524A3 pistons and K1 Technologies rods CH6700APRB8-A).

Is that safe or I need to buy thicker gaskets (I am trying to avoid if not necessary because will cost additional 350EUR with delivery and taxes).

On the following website I can see that for under 6000 RPM engines the valid range is 0.35-0.45 but not sure exactly for my engine: ... /a_id/4941

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