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?

 

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, 20251 yr by Banjo

Awesome, thanks