[skylark65]

I finally got the trans. home, it turns out to be a turbo 400 longtail 3 speed auto. from a 1973 pontiac grandville. my questions are : the bolt pattren on turbo 400 tork converter looks larger then turbine 300 bolt pattren for the flywheel on my 310 wildcat v8 moter.

Next question is: can i use the tork converter from my turbine 300 in the turbo 400 ( my dad slid it into the 400 and it fits splines and pump ok)
but will it be too deep in trans ( back too far) ??

Last question: if above works will I have too much stall speed?

If its of any help, the tork converter is belived to be called a "swich pich"

Any help is greatly appriceated, thanks in advance.

[Crosley]

Switch pitch converter should not be used in a non switch pitch trans.

[joe_padavano]

As noted above, you cannot use a switch pitch converter in a non-switch pitch trans. You CAN convert the TH400 by changing the front pump. PAE Enterprises sells a conversion kit. As for the flexplate problem, there are two converter bolt patterns. You can get TH400 converters with either pattern, or if you have a good TH400 converter it's probably cheaper to get a different flexplate.

[airworld2]

I would like to add this note if you install the long tail 400 you'll need to shorten drive shaft, best to use short tail 400 and replace u joint with off set precision u joint 372 if my I remember correct. you need to change forward input shaft or complete drum depends on what you have on hand and complete pump when converting from switch pitch to non switch pitch.the torque converter in 400 is only in stock form available in 12 inch . the change over works when you a going from switch to non switch if you are going the other way around you'll need more pieces.

[joe_padavano]

Originally Posted by airworld2

I would like to add this note if you install the long tail 400 you'll need to shorten drive shaft, best to use short tail 400 and replace u joint with off set precision u joint 372 if my I remember correct.

I believe the original post was about converting from an ST300 2 speed to a TH400, so the driveshaft will be different no matter which version of the TH400 is used (long or short tail).

[airworld2]

Originally Posted by joe_padavano

I believe the original post was about converting from an ST300 2 speed to a TH400, so the driveshaft will be different no matter which version of the TH400 is used (long or short tail).

I know what the question was, in the old days you would install 350 where the 300 was, and you should be able to use that drive shaft length for a 400 short shaft when you in stall correct yolk. I have changed many combinations from one to the other. some times drive shafts fit and some other's don't.

[joe_padavano]

The short tail TH400 is about an inch longer than either the ST300 or the short TH350. Maybe the ST300 driveshaft will have enough spline overlap (I agree that it's a function of the yoke length), but I wouldn't count on it.

[airworld2]

I've changed many 350 to 400 just had to replace u joint yolk dipstick fill tube and vacume line thats why I know u joint number with out needing a book to cross reference. I can also tell you when you take a 700 from a truck and install a 400 (what I call 375) long tail with a 350 style out put shaft spline you need to shorten drive about 2 3/4 inches. I have tryed many cross breeds in my time in business . before 200 r4 was a popular cross breed I install one in my own 70 gs stage 1 455 and only need to swap out yolk and u joint cable and fill tube now that was a fun inter change and got great gas mileage........