Is BUHW-2 the correct plug for my engine ?

[johninmo]

Hello I have a 87 75 HP Mercury 4 cyl. and I was wondering if BUHW-2 was the correct plug and I also had another question I have read a thread on here about BUZHW-2 and was wondering if they would work with my engine and if they was any better or not

Thank you
John

 

[carholme]

Re: Is BUHW-2 the correct plug for my engine ?

John;

Your s/n 0A116924 (from your previous posts) comes up as:

75 75 (R4) 4-cyl 6613221 0A197881 1985 USA

From here:

http://www.marinshopen.se/Motorer/O...Mercury2takt4cyl4085hp/tabid/487/Default.aspx

It is a model:

1075625 MERCURY 1985 75

Parts Listing:

http://www.crowleymarine.com/mercury-outboard/277.cfm

See item 45 under FLYWHEEL, STATOR AND IGNITION COIL


Here is a condensed version of the Clymer Service manual:

http://web.ebscohost.com/serrc/pdf?...8-9cb4-e7afdb3efdee@sessionmgr14&vid=4&hid=15

If you look at this chart, you will see that the BUZHW-2 is nothing more than a radio resistance plug. Same as the original Delco plugs V40FFM and VR40FFM which you will see in the service manual.

Gerry

 

[johninmo]

Re: Is BUHW-2 the correct plug for my engine ?

Thank you carholme that has always confused me when i look up parts for a 87 75 horse 4 cyl. they dont seem to come up right eventhough that is what is printed on the title and motor and the two (title and motor) serial numbers do match so i have been confused for awhile do you know if this is a common occurance on boats or is it weird lol

Thanks
John

 

[carholme]

Re: Is BUHW-2 the correct plug for my engine ?

John:

I don't think it is all that common though there are certainly some strange ones at times. Most of the time it seems to be one person saying that it must be a certain year as the previous owner told them it was.

Glad we got your s/n squared away.

Gerry

 

[Texasmark]

Re: Is BUHW-2 the correct plug for my engine ?

John;

Your s/n 0A116924 (from your previous posts) comes up as:

75 75 (R4) 4-cyl 6613221 0A197881 1985 USA

From here:

http://www.marinshopen.se/Motorer/O...Mercury2takt4cyl4085hp/tabid/487/Default.aspx

It is a model:

1075625 MERCURY 1985 75

Parts Listing:

http://www.crowleymarine.com/mercury-outboard/277.cfm

See item 45 under FLYWHEEL, STATOR AND IGNITION COIL


Here is a condensed version of the Clymer Service manual:

http://web.ebscohost.com/serrc/pdf?...8-9cb4-e7afdb3efdee@sessionmgr14&vid=4&hid=15

If you look at this chart, you will see that the BUZHW-2 is nothing more than a radio resistance plug. Same as the original Delco plugs V40FFM and VR40FFM which you will see in the service manual.

Gerry

Per my conversation with the NGK service tech, the Z option is an induction coil, not a resistor in the classic sense of radio interference of 50 years ago. Apparently NGK addressed some rough running engines with CDI ignitions and found that the fast rise time of the high voltage pulse radiated into the small signal trigger circuits and caused misfiring and rough running.

They subsequently designed the Z plug to address that issue. Using an inductor rather than a resistor allows you to significantly attenuate the high frequency noise (leading edge of the pulse) yet have a low value of resistance for the main part of the firing current (referred to as the DC value). If you have a CDI ignition, you well may benefit from the change if your engine is running erratic and noise pickup is the cause. It definitely won't hurt anything......course they're about $6.50 a pop.

HTH,

Mark