Prefered Spark Plugs?
 

Just wondering what everyone prefers as far as spark plugs go.
Please note if they are N/A motors or Blown to help keep things straight.

Thanks
Mark

NGK 5673-8 in a blown application.

NGK BR6FS in the little Pachanga

AC Delco MR41T in N/A

I have been running A/C Rapid Fires in the Baja for years. I have had good luck with them. They are part #1

Mine had the NGK 5673-8 plugs in it when I bought it but they were a bit cold for the way i run. I switched to NGK UR5 plugs but I don't run the boat hard. By the way, we dyno'd the first engine with the UR5's and it made 681@5600 with 7 lbs. boost.
Mark, are you interested in trying my Thunderbolts with the V-6 modules? I'll even deliver them if you and Patti can take a break and go to the Oven Grinder for dinner.

NGK V7 N/A 502

NGK UR5's in my 525SC. They are the same heat range as an AC 41.

I had good luck with the Rapid Fire #1's in an n/a 454. Same heat range as an AC 43. They just don't make them cool enough for the 525SC.

What about Bosch plugs?

Thanks Guys, Just wanted to see what everyine was using I've used AC and Ngk's

Dave, The numbers look good on the dyno.!!!!
I got my motor back and it's ready to go back in the boat.
Just need to touch up some paint and polish the valve covers and intake.
I would like to try the V6 modules. I won't need them til summer.
Are you coming in for the COPs party on the 3rd?

Mark

Denso Irridiums. . .Expensive at $12 each but they are the best. BTW, Denso makes NGK's.

Chris

Stef's Performance

blow 468 running autolite 144 plugs, they give a good read

Mark, I don't know yet if we'll be there. I'll let you know.
I'm not going to run the engines at that power output. I'll drop the boost down to 3 lbs, whish should give my around 575 h.p. But it sure sounds nice at 7 lbs. It idles at 800 no-load on the dyno, and at 575 h.p. I should be able to run 65 mph.

NGK all the way. BR6FS

Any problem with running A/C Rapid Fire #10's in a stock 454/330?

D. Ocean
Pompano Beach, FLA

AC Delco MR43T's in N/A 454 Mag.

NA 572 -- Bosch Platinum

Re: Prefered Spark Plugs?
 

NGK 5671A-9's in a 10:1 NA solid roller 598".

Re: Prefered Spark Plugs?
 

NGK 1049 aka B8EFS 461 alu head blown

Re: Prefered Spark Plugs?
 

BPR6FS N/A 600hp. I never had a problem with NGK, tried others but changed back again.

Re: Prefered Spark Plugs?
 

NGK UR-5 - 383 N/A stroker small-blocks.

Having a hard time finding the UR-5 plugs lately. Discount Auto (Florida) alwas had a load of them in stock, but since Advance bought out Discount Auto, they lightend up their NGK line.

Re: Prefered Spark Plugs?
 

What's the difference between a 5671 series NGK and a 5673 series???

I currently run 5671-8 in my Eickerts...Just Curious...

Re: Prefered Spark Plugs?
 

Same here 454/420

Re: Prefered Spark Plugs?
 

I recommend what ever is on sale that has the correct reach and heat range.

Re: Prefered Spark Plugs?
 

I'm using mr43's in a n/a 540. I'd switch to a bosch platinum if I could cross reference the number.

Re: Prefered Spark Plugs?
 

I have found that AC plugs hold up better in a blown application than ANY OTHER BRAND. The Platinum plugs fail under the first hint of detonation and I believe they are the first cause of detonation in a blown motor. Now in the marine industry we only play with 5-psi to 8-psi of boost but the AC plugs (not rapid-fire) hold up very well in applications with 19-psi to 22-psi of boost. been there done that don't want to do it again.