Merc 850XS spark plugs L76V or L78V

N

Nial

Seaman
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Dec 14, 2004
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Hi there<br />I just got a hold of a mercury service manual and it says to use Champion L78V spark plugs with my engine (1976 Merc 850 with NO Distributor). I've been using L76V because the owners manual I recieved when i bought my engine second hand said to use L76V. I looked up the other merc 850 with a distributor and its says to use L76V so I'm assuming I was given the wrong owners manual with the engine. Anyways can anyone tell me is it worth me changing the plugs from L76V to L78V, will this affect the performance of my engine?<br />Thanks<br />Nial
 
L

Laddies

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Re: Merc 850XS spark plugs L76V or L78V

Champion manuel says L76V for all 850 engines the L78V are one range hotter, if it were my engine and was running go on the L76V I would leave well enough alone
 
N

Nial

Seaman
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66
Re: Merc 850XS spark plugs L76V or L78V

I've got the NGK equivilent of Champion L76V in at the moment and they seem to be running fine. So do the L78V run hotter? Can someone explain to me the difference between the two. Thanks<br />Nial
 
L

Laddies

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Re: Merc 850XS spark plugs L76V or L78V

Yes the L78V plug is one range hotter the the L76V
 
N

Nial

Seaman
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Re: Merc 850XS spark plugs L76V or L78V

I've just bought the NGK equivilent of L78V which is BUHW-2. Will see how they go, i'll keep the other set as a spare.
 
ricksrster

ricksrster

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Re: Merc 850XS spark plugs L76V or L78V

I also found two different references on the two plugs. The mercury pocket manual says L78V and the seloc book says L76V. How did you make out with the BUHW-2 plugs?
 
B

Boatwizard

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Feb 15, 2006
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Re: Merc 850XS spark plugs L76V or L78V

With a distributor run the BUHW (L76V), with ADI use the BUHW-2 (L78V).
 
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