Best spark plug for the 355?

That give me something to search for. Maybe I should pull the covers off and do the old "lights out / spritz some water" trick and watch for the light show.

 

Save the work, at the age 355's are at, simply change them all.

 

I ordered 8 spark plug for a 355 (5.2). I asked for PMR7A, but they sent me PMR8B (in a maserati package)...
Some of you say these are the recommended by Ferrari at the moment. Can you confirm this, please?
I need urgent help, because if not, I will ask to change it for the PMR7B..
My user manual says (on pag C 13) Type - NGK R PMR8A, but in the next line says: "...only use other types of spark plug if they have the same thermal rating as NGK R PMR7A plugs.. What a confusion!!!

Thanks in advance

 

Use the pmr7a only in all 355 engines regardless of year. Man im learning a lot around Marcus and Massimo at Daytona.

 

I have a 95 F355 Spider (2.7)

My personal friend and tech, the dealer techs, AND the service manual all state:

PMR7A = 95 2.7 Motronic
PMR8A = 96+ 5.2 Motronic

I'm running the 7s with no problems at all, cold start, shop, or otherwise

Petey

 

Thanks...

Sent plugs back and they will send PMR7A...

But still don´t undestand very well if the 8B will work fine or not..

 

+1, what I heard from my local dealer. They installed the PMR8A based on the current FNA recommendation. That was back in Feb 1998, car runs great!

 

I would only use OEM pugs unless I have ran the engine with a temperature and pressure sensor (did that on my Porsche and previous race cars) to make sure the new plug that experienced advisers would tell me to put in is not to cold nor too hot.
Let's say that original engine runs at max pressure = 95 bars and temp = 150 celcius deg. Now you tune it a little bit, and get 102 bars and 160 celcius deg. Then it makes sense to switch down to one or two higher temperature value (which means 'colder' plug. I don't have the range in mind, but manufacturers provide tables that can be used).

OEM is good

 

A recently learned a rule regarding plug heat ranges, for my application anyway, is to run the coldest plug one is able to without fouling. I upgraded my ignition system to a super-zap system and was having a lot of light detonation at higher rpm due to the extra heat. Changing timing, jetting, plug gap changes were not fixing the issue. I backed off one heat range and the issue was still there. Then went another heat range and the issue was finally brought to rest.

I am not sure if all this transfers to the 355 application or not, but each plug heat range colder represents about 50-100C colder tip temp. You do not want the ground strap to show color past its apex after run hard. If so, I say go colder. Stick with the 355 experts on this one -which I am not- but these are my humble learnings.

 

I just bought a set of Iridium CR8EIX for my 2.7 95 355. I had searched and was told these were the replacement plugs for this car from NGK. Am I to assume that they are incorrect? Also I noticed that the gap distance (.25) is the same as indicated in the manual. Which is it and have I just blown $60 worth of plugs to the wind? Please advise anyone....

Regards,

George

 

I would recommend you follow the advice posted above, and use the factory recommended NGK PMR7A. Previously I tried the CR7EIX on my 1997 5.2 motoronic car, and while they worked fine, my tech noticed later during the major service, that the tip protrusion on the CR series is shorter than the PMR series plugs. I am unsure what this may influence, but obviously, the CR is not physically the same.

 

Hi,
I do not own a Ferrari, but I own one of these:

They called it the "Ferrari for the family man" so close enough, right?

Two things are actually Ferrari on the car, though: The Selespeed semi-manual gearbox and four of the eight spark plugs are borrowed from the 355, the PMR7A.

The ideal replacement would be an IMR7A/IMR8A, which would be Laser Iridium plugs but they don't exist (yet would last upwards of 150k miles on regular cars).

CR7EIX/CR8EIX are not the same either, but judging by the pictures, CPR7EIX are the same, with P denominating a projected insulator:


But they have a nickel ground strap instead of the iridium/platinum pad of the Laser plugs.

 

True, but the NGKs are used for the coil-on-plug conversions without issues that I know of. I ran it in my car prior to my last major a couple years ago, no issues. The reason we used it is because the insulator tip that inserts into the plug cable boot can be removed, leaving a threaded stud on the plug that these coils (on plug) can connect to. The insulator tip on the NGK cannot be removed.

Are the Denso plugs a more exact replacement for the NGKs? If so, are the insulator tips removable?

 

NGK ZMR7AP Period!

Cleaner cold starting, crisper throttle response, less carbon build up during part throttle city driving which equated to smoother part throttle transitions. Also, I didn't think it was possible for a 355 to sound better at WOT but it does.

I know the Stooges will put this to the test...
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What gap?

 

They come .6mm (.023 inch) out of the box.
Set it at .8mm (.031 inch) works best for my de-catted 1995.

 

Spark Plug Test Comparison "SHOOTOUT"

 

so what is the verdict for 355 5.2 ?

 

Also igniting by Denso now in my 2.7 - coming from NGK.
Denso's reliability and reputation was growing since thread start, thus my mechanic is recommanding Denso over NGK, Bosch and others.
Engine run is fine. Got a better feeling with Denso.

 

I wonder ngk 7 or 8 ?

 

My last set was PMR7A for a 1995 2.7 Motronic.
But I recall the days I used PMR8A for my car just because they were written on a dated list. Fouled.

 

Updating an old thread. Just checked the plugs on my 2.7 F355. All were about the same. This was the worst looking one. 13,000 miles on them. PMR7A plugs. A little carbon on this one. No signs of oil so guides.seals (replace 13k miles ago) still seem good. Just a little rich as I would expect for a 2.7 car with my driving style. Both banks the same so the ECU are doing the same thing too.

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My car has PMR7A’s on a 2.7 installed by previous shop/owner with less than 1k miles on them.

I just checked Ricambi’s site and they are still including PMR7A’s with 2.7 service kit.


So what’s the verdict for 2.7 cars? PMR7A or PMR8A (B). I’m curious about the PMR8B.

 

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https://www.ferrarichat.com/forum/threads/what-is-the-official-currently-recommended-spark-plug-for-the-5-2-motronic-f355.381813/