What plugs to run?

Caprimaniac · #1 (**permalink**) 08-31-2008, 01:05 AM

Not so much the brand, but "coldness" of the plugs and material (iridium, palladium, etc) interest me right now, cos' I'll have to get a new set.

- Premium fuel (99 octane- corresponds to about 95 in US
- 347 stroker
- webers
- rpm to 7500
- Edelbrock Jr.
- init. timing 10, max 34.
- Mallory VIA ignition

(I'll post what plugs I currently run later)

Have been searching the forums without luck on this topic.
Rune

Bob In Ct · #2 (**permalink**) 08-31-2008, 05:24 AM

The last engine I saw by Roush came with Motorcraft AGSF32C (SP-447) plugs.

Bob

Rickd · #3 (**permalink**) 08-31-2008, 08:36 AM

My 331 Stroker, built by Keith Craft, has AFR 165 heads, Edelbrock RPM Air Gap intake, Quick Fuel Tech carb, Trick Flow Stage II cam, put out 436 HP at 6000 rpm, on the dyno stand at Keith Craft, and 326 RWHP at 6000 rpm, when I had the car on a chassis dyno tuner in Fort Lauderdale, Fl. (and it was still pulling - the tuner said "I'd take her to 6500 no problem"). Plugs are NGK BKR6E. Using 93 Octane Amoco Super Premium, and very hot, humid south Florida air!!! RD

Roscoe · #4 (**permalink**) 08-31-2008, 08:44 AM

The proper plug is more a function of the head manufacturer than anyone else. Along with my AFR 185's came recommendations for plugs and I've stuck with that for 10 years. You may wish to play with the gap. I run midway 45-50.

Roscoe

ERA Chas · #5 (**permalink**) 08-31-2008, 04:17 PM

Accel 416.

bobcowan · #6 (**permalink**) 08-31-2008, 09:01 PM

There's no magic in a spark plug. Expensive platinum and iridium plags have a coating on the elevtrodes so they last longer. That's it. Just to last longer. That's how they to advetise 100K miles between tune ups.

I use standard Autolites in everything. Simple, economical, never had a failure. In my stret vehicles - truck, wifes car, Harley - I change them about every 40K miles. The cobra goes through 2-3 sets a year. At $1.50 each, I don't worry about changing them.

Caprimaniac · #7 (**permalink**) 09-13-2008, 02:03 PM

Thank you all.
As mentioned, the "temperature" of the plug is a matter.

I checked mine today: NGK FR5.

Which means temperature range 5 ( I guess...)
And Rickd, you use a colder plug, a 6'er.
I was thinking. Maybe a 7'er: ZFR7A or BK7E. That is 2 step colder than what I currently run. After trying 7's in a 3- litre V6 with 11:1 compression and 7200 RPM, I guess the same would work fine in my V8 as well, where the numbers are about the same. (NGK zez: for each engine modification or each 50-100 Hp, - go 1 step colder.)

And for the brand: NGK have never let me down; others have by braking or other misfortunes.

Regards
Rune/RSE

Got the Bug · #8 (**permalink**) 09-13-2008, 03:58 PM

Quote:

Originally Posted by Bob In Ct

The last engine I saw by Roush came with Motorcraft AGSF32C (SP-447) plugs.

Bob

My Roush 402SR/tw came with Motorcraft AGSP32C plugs. Roush's website mentions the Autolite 3923 as the standard plug. Very minor difference, but the Autolite equivalent is the 4924.

Seems to run fine with the Motorcraft plugs, so I'm going to stick with them for now.

Caprimaniac · #9 (**permalink**) 09-23-2008, 10:36 AM

Changed from NGK FR5 to BCP6 E: The engine got a whole new character. Either becaus plugs are 1 step colder or because the plugs were no longer sooty.....

Rickd: Are you running a Mallory or MSD box? If so you might need to change to BK6 E instead of the BKR6.... I had an issue with my Mallory box/ Autometer rpm gauge (both or either; no clear indication yet) and wrote in on their help- desk. One thing they clearly stated was that the plug should be of the non- resistor type. (No R in the NGK- part number..)
RS

Caprimaniac · #10 (**permalink**) 09-18-2010, 10:40 AM

Plugs:

I have now ran Denso- equivalen for NGK 7- grade plugs. Very pleased.

Bought in a set of NGK 8- grade plugs. Are they too cold? Anyone else running grade 8 (NGK scale)?

These are non P- protruding type. P- type is listed for the small block. So, will this have a lot of influence? (Maybe this will give a greater amount of burnt feul/air? Who knows? I fear the opposit will happen.)

RS