J.W. Ultrabell with a 12″ Converter

S3700003Well, i finally got a 12″ non-lock-up th350 style converter in the shop and went to checking out the new ultrabell designs a bit further. in my previous post i was checking out the raptor fab modified ultrabell with the 13″ th400 converter. Well, with the 12″ it fit A LOT better in the housing. there is no bind at all to the housing itself like the old  design. On the older castings you had to clearance the inside diameter of the housing on some installations to insure clearance to the back of the converter.

However, i was a bit shocked at first when i discovered the conveS3700002rter bottomed out on the installation bolt heads of the housing! i was like”what the hell!” But, this was not a reason to panic as it turned out. after mounting a straight edge to the face of the housing and pulling the converter out to the proper installation dimension, it pulled the back side of the converter away from the mount bolt heads almost a full 1/8″ leaving plenty of room for expansion……well other than ballooning of course.


There have been several reports come up now that these have been in the field of play for a while that some of these 12″ converters will not clear the bolts on the front pump, and others have no problem. i attribute this to two factors….the variance in the quality of the converters guys are buying and the use of mid plates for distributor protectors.  the best overall combo i have seenwith the jw housings is the use of the taper head bolts in place of the stock bolts AND a 12″ converter. all in all i like the JW housing, but do not buy one of these things thinkin it is a drop-in and go. you will need to take some time and make sure everything fits….and don’t freak out if there is a problem. you will have to take some time with shimming the converter-the housing-perhaps sending it off to get taper bolts machined it- or even a smaller converter. when everything is dialled in- they are a very nice set up and they win.

It is also worth mentioning that you can now buy the new style jw ultrabell directly from jw performance. i talked with a sales rep directly and got about a 10% discount on the total order. so if you order  3 or 4 at a time it saves you a good chunk of money. it took less than 5 minutes and  you will have merchandise in less than 3-4 business days.    www.racewithjw.com

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