MGB at Santa Ynez Airport

Don Zeigler's 1965 MGB with Pontiac 3800 V6

as published in British V8 Newsletter, Volume XI Issue 3, September 2003

Owner: Don Zeigler
City: Idyllwild, CA
Model: 1965 MGB Roadster
Engine: 3800 GM V6
Conversion performed by: Owner

Engine: GM 3800 Series II from a 1996 Pontiac firebird. Custom idler pulleys were required to replace the power steering pump and the A/C unit. A custom adapter plate allowed for a remote oil filter, mounted to the frame between the sway bar and the radiator. New engine mounts were fabricated and mounted to the crossmember.
Fuel System: An external fuel pump producing 45 PSI (NAPA European replacement) was mounted after a filter in the right battery compartment. The original fuel line was used for return and a new 3/8" pressure line added. The return line enters the tank just to the right of the sending unit. The later fuel tanks may have a port available for return. I am in the process of building a small tank to fit in the right battery compartment, which will be fed by the stock MGB pump with a return to the main tank. The high Pressure pump will circulate through this tank.
Intake: A K&N air filter is placed to the right of the radiator behind the grill.
Engine electrical: The PCM and Body Control computers are mounted on the passenger kickpanel. The donor vehicle had a Pass Key II system. A resistor to match the key was connected to the Body Control Module. The BCM sends a signal to the PCM to enable the ignition. Without the enable signal the engine will start, run for 4 seconds and shutdown. The starter system PCM controls are bypassed. The MG ignition switch still operates the MG solenoid which acts as an interposing relay to the GM starter solenoid.
Cooling: A 1965 Falcon radiator was mounted as far forward as possible, requiring cutting of the body panel in front of the original radiator position. The radiator cap was removed, inlet and outlet ports were relocated to the left side and ports to a Sunbird expansion tank which was mounted on the right side firewall shelf. A14" electric fan just fits between the radiator and the 7/8" sway bar.
Exhaust: Completely custom fabricated including flanges (nothing aftermarket was available at the time). 3/8" flanges, 1 5/8" tubing out the fender wells into 2.50" collectors. 2" exhaust pipe "Y" into the catalytic converter, from the catalytic converter back is 2.25" through a single glasspack muffler. (It sounds pretty mellow until the engine opens up).
Drivetrain: The MG transmission crossmember was modified and used with the RPO M49 (T5) 5-speed. Two of the original mounting bolts were able to be utilized. The GM hydraulic clutch line was adapted to the MG master cylinder. This retains the MG master cylinder and the GM quick disconnect at the bellhousing. (The slave cylinder is inside the bellhousing). A new 2" heavy wall driveshaft was built to mate with the MG rearend. With the 3.909:1 rear axle gear ratio, first gear is useless. I'm looking possibly at an 8" Ford.
Steering: An additional "U" joint just above the frame. The original "U" Joint was replaced with a smaller unit from Borgeson.
Body: Firewall modifications are very similar to a Buick 215cid V8 conversion. The engine and transmission are approximately the same length as the original MGB. A small bulge on the passenger side of the tunnel was all that was required for transmission clearance. The gearshift lever was modified (offset forward about 3" and to the right about 1") to bring the lever into the correct location.
Electrical: 12 fuses now replace the 2 MG fuses. Original Oil and Temp gauges were used, while VDO Series 1 tachometer and speedometer were mounted inside the MG housings.
Performance: With the headers and less restricted K&N air filter, it produces approximately 210 horsepower and 240 foot-pounds of torque - so hang on!

3800 Pontiac V6

MGB steering wheel

direct ignition

Pontiac 3800 V6

exhaust wrap

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