Correct spark plugs for an 888

[ratdude747]

Went to replace spark plugs in my 1976 mercruiser 888... And apparently I ordered the wrong plugs:




The plugs I read were right are NGK A6FS. What came out is a much smaller motorcraft ARF52.

The previous owner's mechanic (my best friend's dad) is a retired Ford tech... So finding car parts is not a surprise. But, the obvious mechanical incompatiblity is a head scratcher.

I don't know if the heads are stock (I've asked; the intake and above are not stock at least).

Serial number:



What plugs should I get?

 

[dubs283]

Autolite 24

 

[ratdude747]

Autolite 24

Noted.

If it matters, I have the stock distributor but I upgraded to Pertronix Ignitor and flamethower.

 

[alldodge]

Manual 2 list to see note 5
Note 5
" 5/8 hex - 14mm plug - AC MR43-T except as follows:
888 (only), Serial No. 4615130 thru 4616217 and 4616217 and above AC R42-T
13/16 hex - 18mm plug - AC CR83-T"

 

[ROY WILLIAMS]

Went to replace spark plugs in my 1976 mercruiser 888... And apparently I ordered the wrong plugs:

View attachment 397107


The plugs I read were right are NGK A6FS. What came out is a much smaller motorcraft ARF52.

The previous owner's mechanic (my best friend's dad) is a retired Ford tech... So finding car parts is not a surprise. But, the obvious mechanical incompatiblity is a head scratcher.

I don't know if the heads are stock (I've asked; the intake and above are not stock at least).

so the Mercrusier 888 manual 1976 serial #4529031 spark plug AC-
MR43-T

Spark Plug Set AC Delco Stainless GM Carb Or EFI Short Reach - 8 Plug Set OEM# MR43-T

Original AC Delco stainless MR43-T short reach plug fits GM pre-Vortec engines. SOLD SET OF 8 SPARK PLUGS - SET OF 8 GM DELCO CARB OR EFI AC Delco spark plug For GM V8 pre-Vortec engines Replaces AC Delco MR44-T Replaces Crusader 97782 Replaces Mercruiser 33-898264001 Replaces Marine Power...

www.myinboardmarine.com

 

[ratdude747]

Already bought autolite 24's... Installing them now.

 

[ROY WILLIAMS]

Noted.

If it matters, I have the stock distributor but I upgraded to Pertronix Ignitor and flamethower.

ENGINE 888 PLUG .030 , 93 OCTANE GASOLINE , TIMING 10 DEG ....DECADES NOW THE 5 DEG ...DEWELL POINT 26-31 DEGREE ..ENGINE OIL 6 QTS .. 4K RPM MAX ..ENGINE OIL 25-40 WT ...

PERTRONIX OF THE ENGINE THE TIMING INSPECT IT !!!!
700-750 RPM IDLE ....

 

[alldodge]

Hey ROY
What ya shouting for ?

Max WOT is 3800-4200 rpm

 

[ROY WILLIAMS]

Hey ROY
What ya shouting for ?

Max WOT is 3800-4200 rpm

THE MANUAL IS MY HOUSE .1979 MERCRUISER MANUAL .

 

[alldodge]

1979 is manual 3
OP has a 1976 and that is manual 2

 

[ratdude747]

FYI, I completed the install and ignition refresh yesterday. Still having fuel issues but I was able to run off starting fluid.

As for the plugs, the autolite plugs fit fine. The AC-Delco plug mentioned later crossreferences to a slightly different autolite plug (145)... slightly different stock gap (0.044 vs 0.040, no, I was lazy and didn't re-gap the plugs) and the resistor value is slightly different (5kΩ vs 4kΩ). Reach is the same at 11mm, and both are nickel plated.

Compared to the AC-Delco MR43-T, both have a different reach (AC-delco 12.3mm) and the socket size is different (13/16 vs 5/8)... and obviously, the AC delco is a stainless plug (instead of a Nickel-plated plug). Napa doesn't list a resistor value... must not be resistor-type plugs.

Oddly, the stainless Delco's are cheaper at Napa than the the Autolite's were at O'reilly's. That said, I'm reading resistor plugs are better for Pertronix ignitions, so maybe resistor plugs are worth keeping?

 

[ROY WILLIAMS]

FYI, I completed the install and ignition refresh yesterday. Still having fuel issues but I was able to run off starting fluid.

As for the plugs, the autolite plugs fit fine. The AC-Delco plug mentioned later crossreferences to a slightly different autolite plug (145)... slightly different stock gap (0.044 vs 0.040, no, I was lazy and didn't re-gap the plugs) and the resistor value is slightly different (5kΩ vs 4kΩ). Reach is the same at 11mm, and both are nickel plated.

Compared to the AC-Delco MR43-T, both have a different reach (AC-delco 12.3mm) and the socket size is different (13/16 vs 5/8)... and obviously, the AC delco is a stainless plug (instead of a Nickel-plated plug). Napa doesn't list a resistor value... must not be resistor-type plugs.

Oddly, the stainless Delco's are cheaper at Napa than the the Autolite's were at O'reilly's. That said, I'm reading resistor plugs are better for Pertronix ignitions, so maybe resistor plugs are worth keeping?

THE Mercrusier 888 manual 1976 serial #4529031 spark plug AC-
MR43-T ....
THE PERTRONIX VOLTAGE 20K VOLTS ...

MY 470MCM MERCRUISER 1978 ENGINE IS PERTRONIX . BOAT 38 YEARS 1986 TODAYS 2024 .. THE GASOLINE IS NO GAS TANK IN THE OCTOBER ..
THE CARB IS NO CORROSION ... DECADES ! DID THE GASOLINE SPRING TANK ..