M:\Product Information\366-348\Instructions\366-348 MGB Fuel Injection Installation Instructions_Grant_2.doc
Installation Part 26 – Tune Up & Maintenance
California Air Resources Board Executive Order Number
The CARB E.O. number for this kit is: D-453-4
IDLE SPEED
Upon startup engine should rev up above 1200rpm and then over time drift down to ~950rpm
depending on the temperature. Different vehicles with various pistons, cams, distributors and
cylinder heads will behave differently, so the actual RPM you see will be different. DO NOT
adjust the idle set screw! If the idle is 1200 RPM or more after the car is fully warmed up, it
means you probably have a vacuum leak between the manifold and the head. See the comments
under Vacuum Leaks below.
SPARK PLUGS & TIMING
Follow the procedure for setting the spark plug gap and timing given in the factory (or Robert
Bentley) workshop manual. Use standard resistor type plug wires. Stay away from solid core plug
wires. The RF will affect the ECU and your car will not run correctly.
COOLING SYSTEM
Keep the coolant system topped off. The late MGB runs hotter to help it meet emission
standards, and running the car low on coolant will create all sorts of problems.
AIR CLEANER
The air cleaner is washable. We suggest using K&N cleaning fluid (231-480) and oil (231-490).
A replacement air filter is available (771-982).
VACUUM LEAKS
Pay particular attention to vacuum leaks as they will degrade performance. The MAP sensor will
see less vacuum than it should, and the ECU will see “load” and it will dump more fuel. You will
be running rich at idle, and the idle will naturally tend to be higher, perhaps as much as 1200 to
1500 RPM.
ADJUSTING THE ECU
The fuel injection ECU is sealed and not tunable. Resist the temptation to fiddle with it.
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