I have a 400 small block and I was wondering if it would bolt up to a t-56. I bought an 86 with a v-6 and auto trans for 1600 and I am going to do the swap. The body only has 54000 original miles and the t-tops dont leak. I NEED LOTS OF INFO/HELP

 

When I first built my '84 I was planning to go with a 400 (or 383), but when I decided on the T-56 I elected to step back to a 350. The reason was at the time the T-56 swap was "relatively" new and there really wasn't a good "easy" solution to for a flywheel that would both work with the T-56 clutch, AND be balanced for the externally balanced 400 crank. If you're going with the aftermarket T-56 and are going to use a standard push-style clutch then there really should be no issue at all, and now there are companies making flywheel/clutch setups for the 400 crank and T-56 clutch setup. McLeod's street twin is one example, although it is expensive it is completely rebuildable and they make a unit for the T-56 with a 400 crank. Beyond that the bellhousing bolt pattern is the same and it will in all other ways "bolt up" to the 400. Hope that helped some!

-Paul

 

I have no experience with this swap, but in my particular situation I've having my engine internals balanced so I will be supplying my flywheel to the machinist for my 400 small block build. At this point it wont matter if its externally or internally balanced but may just cost more for modifications the machinist will have to perform.

ie. I plan on using the stock flywheel off the LT1, having it resurfaced, mounting bolt holes (to the crank) drilled (as they are in a different location than LT1) and also the center hole bored out, that or buy the Flywheel from Centerforce intended for the t-56 to an externally balanced 400 for about $370.

Unless there is a difference of crank flange distance from the block between the LT1 and the 87 pre motors, this might affect the location of the input shaft. I would think that the special flywheel from centerforce would take care of this problem if it exists.

 

An LT1 flywheel will not work on the 400. The LT1 is a 1pc rear seal engine, and the 400 is a 2pc rear seal engine, so the crank flange and bolt pattern are different. You need a special flywheel specifically for using the T56 with the 2pc rear seal engines, and have it 'unbalanced' to 400 engine flywheel specs.