Specifications

system. Do not take short cuts on fuel systems. The new Vortec Gen. III fuel rails have
anywhere between 50-60 pounds of fuel pressure! Only approved high pressure hose
and fittings should be used. Take care when routing fuel lines, and make sure all fittings
are secure. The new Vortecs need a minimum diameter of 3/8” line on the pressure side,
and a minimum of 5/16” on the return (3/8” is best for the return line). The stock Jeep fuel
pump comes close to feeding the new block, but falls short. The stock Jeep fuel pump is
internally regulated in the fuel tank at 46 psi. The Vortecs regulate at 56 psi on the fuel rail.
Since the Jeep regulated the pressure at the tank, it did not run a return fuel line. We
opted to run two new 3/8” lines, one pressure and one return. The pressure line needs
to be installed by drilling and installing a bulkhead-type “AN” fitting alongside the stock
Jeep pump assembly. A fuel tank pick up must also be installed. Make sure the new
pickup line draws from the bottom of the tank and has no restrictions. The old Jeep
“pressure” line out of the tank can be used as a return line connection from the Vortec. To
use this connection you must take all the “guts” out of the stock internal regulator.
1987-2005 JEEP WRANGLERS:
Chevy V8 conversions in these years, replacing the 4 cylinder and in-line 6 cylinder engines, are very popular. We have a complete
line of bellhousing adapters to use any one of the original stock transmissions. We also offer a full complement of transfer case
adapters, adapting to many of the Ford & Chevy transmissions.
A. Stock Manual Transmissions: If your vehicle was equipped with a 4 cylinder, the transmission would be an AX5. This 5
speed is considered to be a light-duty transmission. We offer a full bellhousing kit to mount this transmission to either a Chevy V6
or V8 engine. If your vehicle was a 1987-89 YJ equipped with a 4.2L 6 cylinder, then the transmission would be a Peugeot 5 speed.
This transmission is also considered to be light-duty and unreliable; however, we do offer a full bellhousing kit to retain this 5 speed,
coupling it a V6 or V8. NOTE: This bellhousing will retain the internal hydraulic release bearing. The AX15 5 speed transmission
was first used in 1990, and the NV3550 in 2000. These transmissions were used in Jeeps with a 4.0L 6 cylinder. These
transmissions have an excellent gear ratio and are ideal for a V8 conversion. These transmissions are probably the only newer
Jeep manual transmissions capable of handling the engine torque of a V8. We offer a full bellhousing kit to retain the stock
transmission to a Chevy engine; P/N 712567 for the AX15 and P/N 712591 for the NV3550. We also offer an adapter plate, Part
No. 712543 (AX15) & 712544 (NV3550), for Ford small block V8 applications.
All of the bellhousings for the above mentioned stock Jeep transmissions are all limited to a 10-1/2” flywheel & clutch assembly.
The clutch linkages on these applications are always hydraulic, and are either mounted on the bellhousing or the front of the
transmission. Please refer to the 1987 & Newer Stock Transmission & Bellhousing Adapter section for more information.
B. Stock Automatic Transmissions: If your vehicle was equipped with a 4 cylinder, the transmission would be a Torqueflite
904. This automatic is not recommended when installing a V8. If your vehicle was equipped with a 6 cylinder, the transmission
would be a Torqueflite 999. This transmission works great with either the Chevy V6 or V8 engine conversions. For more information
on retaining these stock automatics, refer to the Stock Transmission & Bellhousing Adapter section. All of the transmissions listed
above are found in both the YJ & TJ Wranglers. The following information is based mainly around the YJ conversions. Nevertheless,
this information may be applicable since these vehicles use mostly the same drivetrain (transmission & transfer case). We have
had some customers replace their stock transmission using the T18 4 speed and the NV4500. Both customers were forced to
reposition the air bag module and some console modifications to provide room for the new manual gear lever.
C. Optional Transmissions: We offer numerous types of transmission options that could be substituted for the original Jeep
transmission. The options for the Chevy conversions would be the GM automatics such as the TH350, TH400, and 700R-4; and
for the manual transmissions, the NP435, T176, T18, SM465, SM420, and NV4500. The transfer case equipped in these vehicles
is manufactured by New Process Gear, and came equipped with 21 or 23 spline input. For more information, refer to the Transfer
Case section of this manual.
D. Exhaust: We offer two styles of header systems for a Chevy V8 in these late model Jeeps. The inside-the-frame rail headers,
P/N 717011-NP, drop straight down inside the frame rails, similar to centerdump manifolds. Part No. 717039-NP is a complete
tubular header system that is designed to fit Jeep vehicles 1987 to 1995. These headers exit over the frame rails and drop down
between the fender skirting and firewall. These headers are not compatible with vehicles equipped with Nerf bars. For Ford V8s,
we offer P/N 717012-NP, which is an inside-the-frame rail header.
E. Radiators: The original radiator can be retained in the stock location. The inlet and outlet positions
will require relocation for a Chevy engine. An optional electric fan can be installed for additional cooling
capacity. Consideration should be taken as to upgrading to a larger, more efficient radiator.
F. Driveshafts: On Chevy V8 installations, retaining the stock transmission, the original driveshafts
should not require modifications. When upgrading the transmission, driveline modifications should be
expected.
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AA’s Vortec & Atlas test vehicle, Moab 2004
conversion application summary (1987 & newer)