I’m still looking for a precombustion chamber for my D2 3J. I have a couple leads, but in the meantime I wondered :

Are there other prechamber that maybe don’t fit ( exactly) but would with a little machine work ? Several companies make after market chamber for the bigger cats, that’s why i ask.

Thanks for any ideas.

TOGNOT wrote:

I’m still looking for a precombustion chamber for my D2 3J. I have a couple leads, but in the meantime I wondered :

Are there other prechamber that maybe don’t fit ( exactly) but would with a little machine work ? Several companies make after market chamber for the bigger cats, that’s why i ask.

Thanks for any ideas.

This is totally from memory so I can't verify any of it but I read it on the bulletin board in the past. Someone was having similar problems locating precom for a d2 and it was suggested that a d4 chamber could be turned and rethreaded to fit a d2. I don't know if this was d4400 to d3400 or if the u series stuff will work also. I can't give you the thread pitch either. I did a couple of searches with the search option and couldn't find anything. Maybe some more knowledgeable will help out

Whats the bore diameter for the early chamber. If it's 2-1/8" that's the same as the early D4 which has a length of 3-1/2" from seat to top of chamber. Thread size on the D4 is 1-1/8"-12 tpi, the D2's are 1"- 12 tpi. The D4 chamber is part # 8B0493 which I believe are still available.
Any luck finding J model later chambers? Threads on the D4 chamber can be re-cut and some reshaping of the chamber transition to the threads are probably required. Basically this is the same task the rhpig offered for the later U model D2's.

Thank you - that’s what i needed - some dimensions. I don’t have the head and the removed chamber here with me, but ill find out and report back.

Here's a picture of an altered D4 chamber for use in the "U" model D2's as offered by jhpig on here.
Similar alterations would be required for the "J" models.

Thanks for the picture. I found a drawing online for the part number you listed earlier ( 8B0493 )

Neither the diameter nor the thread size is correct for the 8B0493 as shown in the drawing.

Gotta love the internet. Ill keep looking.
Thanks for the info.

I think I Have some Good D2 chambers Enroute . But to follow up onthis topic :

Measuring the D2. Head :: prechamber “bore” at the top about 2 1/8”. Distance from combustion chamber to top Of prechamber sealing surface :: 4.25 “


When the new/used chambers arrive I Will Document the dimensions

That would be a match for the 8B0493 at 4.25" overall length.