New/ used pre chambers arrived. I will get all the measurements before they are installed so we can compare them to other cat models.

Three years on and I am helping a friend locate pre combustion chambers for his 1941 3J5471-SP D2 dozer with a 1947 5J9658-SP engine. On removing the existing chambers one broke off at the thread, and a couple were rusted through. The chambers appear to be 101.71mm in total length with a 1" thread at the bottom and an external diameter at the top of 55.22mm. Has anybody got any spares lying around (grasping at straws) or can suggest a suitable replacement with or without further machining? Cheers - Lou 

Still listed at Regal, 8B4440 for the later 3J, 5J.
Give them a call.
 

Thanks Old Magnet! Just to confirm, is the pre combustion chamber I am looking for (pictures on my last post) the newer type? It has a 12-point hex inside which I assume is the means to install or remove the chamber. I gather that there was an earlier type with a reverse thread for the installation and removal. And it is the newer type that is part number 8B4440? Cheers - Lou

8B4440 is the later one piece style.

Thanks Old Magnet, appreciated. That makes it clear now.

Regal USA have advised that the 8B4440 is no longer a stocked item, so still on the hunt!

Cheers - Lou

There still may be some out there...www.machinerytrader.com/parts/search?Par...440&SearchType=Start
 

Thanks once again, Old Magnet!! I am following this one up as well. Your assistance is very much appreciated!! Cheers - Lou

One more source to try...WWW.offroadeq.com out of TN.