Quick spark plug question on what plug to use in tbi conversion for sbc.

So i did some googling but did not come across a clear answer. Engine is a 1978 350 low compression. I am sticking with standard copper core ac delcos but i want to know whether i should use the spark plugs recommended for the engine when it was running a carburetor or if i should use the recommended plugs from a 350 tbi equipped truck? I am not sure if the different heads warrant different plugs ie (i should use the plugs recommended for my heads rather than the tbi plugs because i dont have tbi heads) or of the whole efi system requires different plugs because if how the fuel is delivered or something? I hope thats understandable. Thanks

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Originally Posted by joegreen

So i did some googling but did not come across a clear answer. Engine is a 1978 350 low compression. I am sticking with standard copper core ac delcos but i want to know whether i should use the spark plugs recommended for the engine when it was running a carburetor or if i should use the recommended plugs from a 350 tbi equipped truck? I am not sure if the different heads warrant different plugs ie (i should use the plugs recommended for my heads rather than the tbi plugs because i dont have tbi heads) or of the whole efi system requires different plugs because if how the fuel is delivered or something? I hope thats understandable. Thanks

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Joe,

Stick with the factory recomeended plug style but drop 2 heat ranges. Most trucks run a R45TS back in those days. TBI engines usually run a 43 heat range.

Cool thanks.I'll use the lower heat range plug for my head.