Tony&CJ Posted June 3, 2025 Report Posted June 3, 2025 Hi guys, I just purchased this 4K with a 5 speed bolted up to it, I think it may have been in a van originally, and I thought they all had flat top pistons. Any ideas? Quote
Banjo Posted June 3, 2025 Report Posted June 3, 2025 (edited) Hi Tony, Have a read through this post, about 8 years ago, where this subject was covered. https://www.rollaclub.com/board/topic/73368-4k-change-pistons-to-flat/ https://www.rollaclub.com/board/topic/40853-what-pistons-are-these/#comment-433565 There are two types of 4K blocks. You have a simple 4K block. There is another 4K-U block, which developes more HP. I have one of those in my KE-30 2 door. There is a picture in the Toyota yellow K Series engine repair manual, which shows a picture of the mark on the piston, that must be positioned to the front of the engine. It depicts two A & B type pistons; the only difference; one being flat topped; & the other is partially dished; exactly the same as your photo. The little single dot indentation in your pistons, should point towards the front of the engine. There was also a 4K-C engine produced, that according to the Toyota workshop manual; were only exported to Australia & Sweden. The C, usually meant that the engine complied to Californian emissions regulations; as that state was, I believe; was the first state in the USA, to create emission requirements for gasoline engines. Cheers Banjo Edited June 3, 2025 by Banjo Quote
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