What is the gap for a bosch spark plug on a ford falcon bf lpg

.054 inch.

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A lean mixture is causing this fault, It is important to have this repaired. if lean only on start not a big fault. if lean on running under load it will burn exhaust valves and top of pistons.

Sound like a problem in the LPG system - Take it to a LPG Specialist/Auto Electrician - will save a lot of heartache and probably a lot of money - nothing like advise from someone that knows what he is doing ??? Forget the local mechanic.

I think you need a special long spark plug socket to reach the plugs because the plugs are deep in the cylinder head if hemi type engine, hope this helps!

0.052inch to 0.054 inch

0.052 inch to 0.054 inch

run a scan on the car

Dear god. none of you sound like you know what your doing.
The Bosch HR 78 NX spark plug is a super 4 plug that has 4 outer ground electrodes and uses surface air gap technology.

There is no need to mess about gapping the plugs as they are Factory pre-gapped electrodes.

• Higher ignition reliability thanks to eight possible ignition gaps
• Self-cleaning thanks to surface air-gap technology
• Increased thermal range: up to three times as many cold starts possible as with conventional spark plugs

So don't mess about gapping your super 4 Bosch, Just fit them.

do a compression test to make sure it is that cylinder.

once determined it is that cylinder, put a teaspoon of oil in the spark plug hole. If compression comes back then the vave is burnt, if compression stays down the rings are bad