Specifications

V8. The Jeep we purchased was a 1988 YJ Wrangler equipped with a 6 cylinder, Torqueflite automatic transmission, air conditioning,
power steering, and power brakes. The transfer case this Jeep was equipped with was a New Process 231 with a vacuum shift
control that actuated the front differential. As we began to research this application, we also decided to upgrade the transmission
to a TH350 automatic.
The new engine that we selected for the conversion was a new 1986 Chevy 350 V8. The engine was equipped with the standard
"H.E.I." distributor. In this section, we have listed some of the different areas of concern that might be of interest if you are performing
a similar conversion. The conversion took approximately 60 hours to complete.
Transmission: The stock transmission was a Torqueflite 999 automatic. The NP231 transfer case was
coupled to this transmission using the factory adapter. We learned that the bolt pattern of the NP231 was almost
identical to the Jeep Dana 300 transfer case used in the earlier 1980-86 model Jeeps. By using P/N 50-6304
(or 50-6300 shown right), we were able to mate the new TH350 transmission to the existing transfer case.
We used our crossmember mount, P/N 716017, to attach the original crossmember support to the
bottom of the new adapter housing. The location of the transmission mount needed to be changed
slightly on the skid plate. The transfer case remained exactly in the original location. This location
may vary on vehicles equipped with different transmissions and engines. The transmission cooler
lines that were originally used for the Torqueflite were retained and reconnected to the TH350 by using
two small rubber hose connections. The original column shift linkage can be retained, but it is easier
to use a floor shifted cable-operated shifter for controlling the transmission.
Engine: The engine mounts that we used were P/N 713007. The existing 6 cylinder mounts were completely cut away from the
frame, and the new brackets from our kit were welded into position. The location of these new mounts will be determined by the
assembled length of the new transmission, adapter, and transfer case when assembled into the vehicle. The engine was centered
between the frame rails. The oil filter was replaced with a new oil filter bypass kit, P/N 716083. This kit was required since the
front driveshaft is located on the driver's side of the vehicle.
In our installation, we used a 2" fan spacer to keep the fan close to the stock radiator. The engine must be equipped with the late
model long water pump that has the extra four holes for use with the power steering and alternator brackets. The exhaust system
was the standard Chevy ram horn (centerdump) design; or you could use our fenderwell headers, P/N 717039. The linkage on
the carburetor was easily connected to the existing throttle assembly. The Jeep engine had a single Serpentine belt drive. When
switching to the V8, we found it easy to convert all of the accessories to the standard V-belt design. The original Jeep fan operated
in the opposite direction of a Chevy V8 fan, so a different fan was required on our new engine. The crank pulley that we used was
a three groove design, GM# 4023148. A two groove design was used on the water pump, GM# 14023155, and used to drive the
following: 1st groove - For the alternator, water pump and crank; 2nd groove - For the crank, A/C and power steering; and 3rd groove
- Also for the crank, A/C and power steering
Brackets: There are two areas that require brackets. Using all GM stock brackets, we were able to simplify the installation.
Alternator Mounting Brackets: The alternator is installed on the right side of the vehicle. We selected a 33 amp internal
regulator model alternator. The unit was mounted with three stock GM brackets. The brackets listed below were the GM part
numbers used. The electrical wiring connection that was originally used on the Jeep was simply plugged back into the new
alternator. Top Bracket #14081227, Lower Front#14015533, Bolt #3932414, and Water Pump to Alternator #6262934.
Power Steering Brackets: We retained the original Jeep power steering pump and used a pump mounting bracket from a
1986 Chevy truck. This stock bracket required an additional rear support that bolted between the adjustment slot of the power
steering bracket and the Chevy manifold. Since the Jeep power steering pump had the wide groove pulley, we had to remove
the stock pulley and replace it with a new two groove V-pulley. The second groove on this pulley will be used as an idler for the
air conditioning compressor.
Stock Gauges: We were able to retain all three of the engine operating gauges. The alternator amp gauge works without any
modifications. The electrical engine temperature gauge sender that was originally installed with the 6 cylinder was reinstalled by
using a standard bushing adapter. The wire for this sender will need to be lengthened for use with your new V8 engine. The oil
pressure sender was simply reinstalled using the 45 degree pipe elbow and, once again, the electric wire needs to be extended.
Vacuum Connections: There are several areas that will require vacuum fittings from the new engine in order for the vehicle to
operate properly. We suggest that you purchase a multi-port vacuum connector, GM# 355786, that can be used for the various vacuum
connections.
1. 4WD Shift Control: The Jeep transfer case operates off a vacuum control linkage system that is regulated by a vacuum
reservoir, located on the lower right side of the engine compartment. This vacuum reservoir requires a vacuum line
connection.
2. Power Brake Booster: On the multi-port vacuum line fitting, there is one large connection that must be used for the Jeep
power booster vacuum line.
3. Heater: The heater control must have a vacuum-fed line.
4. Charcoal Cannister: The charcoal cannister is an area that accumulates excessive gas fumes and requires a vacuum line
to be connected.
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conversion application summary (1987 & newer)