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TH350-400-700R4-200 4R and PG to early
Chevrolet & GMC 6 cylinder engines
With the advent of the Stovebolt
Transmission Adapter the installation of the GM TH350, 200 4R and 700R4 is
made possible. This requires
an "open" driveline and cannot retain the torque tube.
In addition to the rear axle, the installation of a transmission cooler, shifter, and T.V. cable mounting make
this a project not intended for the novice.
We strongly encourage the use of
a 200 4R in combination with a 3.73 or 4.10 axle ratio so your efforts
will result in a satisfying combination of low speed performance and highway
cruising at modern speeds up to 70 MPH. The THM 350 could be used at a
substantial loss in low speed and highway cruising (both). The use of
the Powerglide is strongly discouraged.
The original design
of our transmission adapter used measurements from 25 engines and 50
bellhousings. We
found that GM was off as much as .020" from centerline on many manual shift
engines, and even on some matched set Hydro-Matic engines. We then took the
average to build our adapter. In occasional cases of too much run out (.012"),
the use of eccentric dowels will be required. Currently, however, both dowel pin
location specifications are the exact factory blueprint dimensions machined
exactly by CNC technology and assured on every adapter by assembly and dial
indicator. Checking on your block and with your transmission is
recommended.
To start, unbolt the four bolts that hold the
factory transmission to the bell housing, and pull out the transmission.
Remove the throwout bearing, the pressure plate, and the clutch disc.
We are now down to the flywheel which must
be removed before the bell housing. The flywheel is held on by bolts that are
retained by a flat metal strip that has tabs that are bent over to prevent the
bolts from turning. Use a chisel to flatten the ears before removal. After the
bolts are out, carefully remove the flywheel. Now you are ready to remove the
bell housing. Remove the 6 retaining bolts and now remove the bell housing.
Clean the grease and dirt off the back of the block and install the adapter
plate.
Our kit comes complete with a spacer for
the crank and a flexplate that has been re-drilled to Chevrolet 6 cylinder bolt
pattern. Remove the 3 dowels from the
crankshaft and install the spacer then the new flexplate using the special washers
provided.
Set the transmission on a transmission
jack and strap it down. Carefully install the converter to the transmission
turning it with light pressure to insure it slips into the pump. Lift the
transmission into place and install mounting bolts. Now turn the converter to
line it up with the flexplate and slip it forward. Install the mounting bolts.
It's a good idea to use Loc Tight on these.
This kit requires the use of a 250 Chev 6
starter (part # Delco 323-236). It may be necessary to make a slight notch in
the starter housing for clearance to the flywheel teeth. We strongly
recommend purchase of this starter from Langdon's Stovebolt to assure proper
engagement, shimming and clearancing.
Rear support for your transmission
Chassis Engineering in West Branch, Iowa (319-643-2655)
makes a good selection of kits for supporting the transmission at the rear
mount. This will work well if your engine is side mounted but will not
be adequate if you are using the front mounting plate typical of 1937-1951
cars and '37-'54 trucks. In these cases it will be necessary to
fabricate mounts similar to the original bell housing type mounts typical of
'55-'57 Chevy passenger cars.
(revised 7-24-06)
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