Best spark plugs for the 575SCi?
#1
Registered
Thread Starter
Best spark plugs for the 575SCi?
I am looking for opinions on spark plug manufacturers for the Mercury Racing 575 SCi. I am currently using an NGK R5673-8, but just had 2 of them fail at about 40 hours of use. I was expecting to get a little more time out of them. What are you all running in your 575's? Thank you for the feedback.
#2
Registered
The plugs you are running are too cold. With NGK plugs, the higher the number, the colder it is. You should be running a 7 series plug. In you case, NGK R5673-7.
Eddie
Eddie
#3
Banned
iTrader: (9)
Eddie Merc is still recommending R5673-8 thru out all 575 sci engine serial runs. Just wondering is plug fouling the issue as to why you are saying -7 instead of 8. Thank you for your time
Will post this as well we have seen a few bad plugs coming from NGK as of this year that have never been experiencing before. Not large amounts but one here and there.
Will post this as well we have seen a few bad plugs coming from NGK as of this year that have never been experiencing before. Not large amounts but one here and there.
#4
Registered
iTrader: (1)
Factory plug is the NGK R5673-8. Merc# is 33 - 8134214
That's all I have for info. Have done nothing with these motors other than some ported throttle bodies.
Edit in: BUP sent his post faster than me. LOL. Time for more coffee.
That's all I have for info. Have done nothing with these motors other than some ported throttle bodies.
Edit in: BUP sent his post faster than me. LOL. Time for more coffee.
#5
Registered
iTrader: (4)
I am looking for opinions on spark plug manufacturers for the Mercury Racing 575 SCi. I am currently using an NGK R5673-8, but just had 2 of them fail at about 40 hours of use. I was expecting to get a little more time out of them. What are you all running in your 575's? Thank you for the feedback.
It may not be just the plugs, the stock tune startup enrichment is retarded, AFR from 8-9 until fully warm. The stock tune is rich all around. Also scan for intermittent engine coolant temp and MAP sensors issues. I have had one of each over the years, not enough for the code, just readings that didn't make sense. Both issues caused fouled plugs.
Last edited by 4bus; 08-20-2014 at 10:02 AM.
#9
Platinum Member
Platinum Member
Join Date: Jul 2008
Location: Little River SC
Posts: 931
Likes: 0
Received 0 Likes
on
0 Posts
I am looking for opinions on spark plug manufacturers for the Mercury Racing 575 SCi. I am currently using an NGK R5673-8, but just had 2 of them fail at about 40 hours of use. I was expecting to get a little more time out of them. What are you all running in your 575's? Thank you for the feedback.
#10
Registered
I've had much better luck with the 7's since those engines are so rich. As long as you are running the recommended 91 octane or better, you will have no issue at all with the 7's. It will run cleaner and is less likely to foul plugs at idle with the colder plugs. Now this only holds true for stock engines. In 4Bus's instance, he's changed pulleys (I believe), so it all depends on the boost he is running as to which plugs I would run.
As Mark (MER) mentioned, you may be in need of an ignition system tune up. If the plug wires are more than 3-4 yrs old, change them out. Same for the cap and rotor.
Eddie
As Mark (MER) mentioned, you may be in need of an ignition system tune up. If the plug wires are more than 3-4 yrs old, change them out. Same for the cap and rotor.
Eddie