MushroomSouprise Posted February 28, 2023 Share Posted February 28, 2023 Hey, just bought this 73 240z recently and it looks like the #1 cylinder has rust on it. Am very new to engine work and was wondering if this is something I can hone out or will it need to be machined? The pistons were also filled with this gunk when I took the head off and there are marks on the pistons. I thought the marks might be the valves hitting but what about all this gunk? Quote Link to comment Share on other sites More sharing options...
AydinZ71 Posted February 28, 2023 Share Posted February 28, 2023 That first image with the rusted cylinder wall... this engine needs to be rebuilt. The machinist will need to remove material until the pitting/rust has been completely removed. Then he will match the remaining cylinders to the one they needed to remove the most material from. Depending on how much was removed, they will either use the OEM piston with a larger dia. ring, or up upsize to the next diameter piston + rings. Your valve seals will likely need to be changed too. $1000-$3000 of work and parts depending on what can be re-used. Can you clean it all up and try to run the engine? Sure...buy why. You will have poor compression, will likely burn oil, and all around be disappointing. Is this your OEM original L24? If the numbers match and you like the 2.4L, makes sense to rebuilt. Otherwise, I would toss it and find a running L28. You could get a long block for under a grand, and your SU carbs will work just find with it. Everything else is the same except displacement. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 28, 2023 Share Posted February 28, 2023 The crud could be from antifreeze that leaked in from a blown head gasket. The engine does look pretty beat up. Aftermarket pistons and rings are getting harder to find, especially oversize. Better source parts before you have any machine work done. People are out there right now with freshly machined blocks and nothing to put in the bores. Can't find the parts. Make a spreadsheet and fill it out, see what will work and how much it will cost. A used L28 might be the best route, as suggested. They were used all the way through the 280ZX years, 1975 through 1983. Quote Link to comment Share on other sites More sharing options...
MushroomSouprise Posted March 2, 2023 Author Share Posted March 2, 2023 Appreciate the advice guys, I have a lot to think about but I'll put together a parts list for both options and see what it's going to take. Quote Link to comment Share on other sites More sharing options...
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