big66440 Posted June 26, 2015 Share Posted June 26, 2015 I was wondering if the H802CP pistons could be used in an 89 4.0 with a 7120 cylinder head? the only difference I was able to see was the H802CP pistons had about a .007" taller compression distance than the correct ones listed for the 1989 4.0 engines ( part number 677AP). Reason I ask is because the H802CP pistons have a coated skirt, they're cheaper and according to the federal mogul website they are 165 grams lighter per piston/pin combo compared to the 677AP. Link to comment Share on other sites More sharing options...
Jeep Driver Posted June 26, 2015 Share Posted June 26, 2015 Without looking it up, I doubt the .007 is even the thickness of the head gasket. I forget what Sealed Power pistons I used.........they are just about all coated anymore. I assume you are going with a full set? for weight difference? They should be fine. Link to comment Share on other sites More sharing options...
johnj92131 Posted June 27, 2015 Share Posted June 27, 2015 802 piston is hypereutetic while the 677 piston is a cast piston Link to comment Share on other sites More sharing options...
cruiser54 Posted June 27, 2015 Share Posted June 27, 2015 Head gasket is at least .052" thick. I'd use them. Link to comment Share on other sites More sharing options...
Akula69 Posted June 28, 2015 Share Posted June 28, 2015 Did use them in an 88 rebuild without problems. Link to comment Share on other sites More sharing options...
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