Purchasing Spark Plugs - Who's & Where

I buy my plugs from RockAuto.com, I use MR43T , the T and the LTS are the same price. You pay $1.60 per plug for a package of 8 plugs, plus shipping. The individual price is $1.84 each.

Last year I bought 16 and paid less than $2.00 each which included shipping.
 
I put together a maintenace chart yesterday for my engines and no where in the mercruiser manual could I find a replacement interval for the spark plugs. Since I couldn't find it, what is it?
 
I do mine every spring. At only $50 a set, its one of the cheaper maintenance items. Stupid water sep element is $40.
 
Newbie said:
Trust the Merc TSB link in my above post

The merc TSB calls for 932's for 05 and earlier and 993's for april of 06 and later. It also goes on to say:

"AC 41-932 spark plugs (P/N 33-884019) will be replaced by AC 41-993 spark plugs (P/ N 33-884019001). The spark plugs are fully interchangeable. Serial number breaks
have not been recorded." So, either plug will work

The same TSB has a statement for the misprint in your manual where it calls for the 983's, (there's even another TSB for the misprint on this TSB) won't hurt your engine but are not the recommended plugs.

"In some owner's manuals, the AC 41-993 (Misprint should read 983) spark plug used in 496 and 8.1L engines was
incorrectly listed as the appropriate spark plug for 4.3 MPI, 5.0 MPI, 350 Mag MPI, and
MX 6.2 MPI engines. The heat range and the thread length of these spark plugs are
correct. The firing tip on the AC 41-983 is longer and extends slightly deeper into the
combustion chamber than the correct AC 41-932 (now being replaced by AC 41-993)
spark plug. While the AC 41-983 is not the recommended spark plug, its use will not
harm the engine or its performance."

Hopefully that clears it up for you
Click to expand...

Thanks for the info and link Newbie! :smt038
 
I've developed a preference for BOSCH plugs. But I Don't ever get to replace them because they never go bad.

100 Hours on plugs with an electronic ignition. Thats like having to change plugs in a car every 4,000 miles. If the plugs are in fact bad ... there maybe too much resistance in the wires and causing burning. Changing plugs for no reason doesn't make sense.
 
I bought on line from Rockauto.com. They had better prices. I bought the irridium plugs. Only bled a little bit from the installation process. I must be getting better at it.

Rock Auto has a great selection.

Dennis
 
Asureyez said:
100 Hours on plugs with an electronic ignition. Thats like having to change plugs in a car every 4,000 miles.
Click to expand...

4,000 miles, up hill, towing a trailer, at 2 mpg, 3500 RPM.
 
John,

I meant to ask you in the PM - how many hours do you have on your 8.1s? Is this your first plug/wire change?

My dockmate's '04 340 would only turn 2600 RPM at WOT - he needed plugs (but no wires) and fuel filters at 150 hours. After that it ran to spec.
 
358 hours. 2nd set of replacement plugs. 1st set of replacement wires. Right engine misses a little in low - mid range RPMS on occassion. Spark plug wires seem to fit loosely to end of plugs (a couple of them).
 
I have 350 hrs on original set. I guess it's time to replace. Should I do wires too? Any good source on OEM wires? Is there a distributor cap & rotor too? Its a 2003 5.0 MPI runs strong.
 
I went to Merc's "Parts Express" site, registered my Engine's SER# and plugs show up on there for $3.98ea. Not sure I can beat that anywhere else.
 
The wires came in the mail and look solid.

The AC Delco plugs fixed the starboard engine's missing. I'll do the wires before our big trip. The original wires were AC Delco, interestingly.
 
Just as a FYI to anyone that has a 496/8.1 MerCruiser engine that might be looking for a newer set of take off spark plug wires at a very good price versus going new at a Factory list price of $575.30. Raylar marine in San Diego CA, a Hi Performance engine builder for the 496 engines has a high number of take off wire sets that he sells for around $75.00 a set. It would be worth a call to see if Ray can still help some of you out while he still has them in stock. Below is his Quote from a different forum with his info.

The 496 Superstore!
We at Raylar have new Mercury OEM take off plug wire sets in stock for 496's @ $75.00 set plus your choice of UPS shipping time.

Best Regards,
Ray #@ Raylar (866)-496-8181
http://www.raylarengine.com/

WIRE KIT, (8 Leads), Spark Plug4,5$575.30$489.011
Or to show you take a look at part number 34 in this link from MerCruiser. http://www.mercruiserparts.com/Show...7.png&inbr=12826&bnbr=100&bdesc=Cylinder+Head
 
Advance Auto Parts seems to have a decent deal going online right now. Spend a hundred bucks, get 20 off and free shipping.
Just bought 16 AC 41-983's and a couple microfiber towels (to get it to $100) for $80.
 
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