Ironmike
Well-Known Member
NGK BKR6E 11.25 to 1 with aluminum heads. 5's are too hot for my taste.
What plugs are You Running in Your 408 Strokers.
- Thread starter TimS
- Start date
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TimS
Well-Known Member
I’m running a QFT Holley 750 and Weind intake.
For the avatar's 408 (Eddy heads, 10.5 actual CR), I started with Champion RC12YC. Those didn't last long as I had 2 plugs where the center electrode got pushed up into the ceramic body leaving no middle tip! I worked with a Champion rep in our engine group (I worked for one of the OEM'S) and he stated these are very old technology plugs. He said the seal inside the plug to keep the gasses inside are made of compressed talcum powder(!) and this was a known failure mode that was since long ago addressed with their other/newer plugs. He gave me a recommendation for a different Champion plug but when I looked at them, they were like $11/plug!
Nope - not gonna do that so I went to Autolite 3924 plugs (cost then about $1.80 each) and have never looked back. These plugs seem to be fine at the track as well as putting around on the streets. My $0.02!!
Nope - not gonna do that so I went to Autolite 3924 plugs (cost then about $1.80 each) and have never looked back. These plugs seem to be fine at the track as well as putting around on the streets. My $0.02!!
Ironmike
Well-Known Member
don't they make a Race 3924? Or maybe it's a Race 3923......
Whichever one was a Race plug, I ran them for awhile with no problems, other than price. The NGK's were cheaper.
I don't know about race plugs. I think I got these Autolite 3924's at O'Reilly's for about $1.80 each about 3 years ago.
Must be nice. Those plugs and the NGK 6962 are $6/ea up here.
Gator
Mopar or No Car
NGK V Power Copper
Champion RCY12C, 408 ci, W2 heads, MSD 6AL ignition, runs great
MOPAROFFICIAL
If it has tits, it's a liabilititty.
Don't tell anyone.. but i run NGK GR4GP
SHHHHHH
SHHHHHH
Ironmike
Well-Known Member
Man, that is a screamin hot plug!
MOPAROFFICIAL
If it has tits, it's a liabilititty.
How hot is too hot?
Check the discoloration on the base ring and count the threads of discoloration.
Timing, the strap, wot? The deepest portion of the insulator...and on n on.
I ran those gr4gp .030 quench with iron heads, 9.98 comp and 8.3 or so dynamic and 28 total timing on 91 chevron.
Did the testing and checked everything to know.
Check the discoloration on the base ring and count the threads of discoloration.
Timing, the strap, wot? The deepest portion of the insulator...and on n on.
I ran those gr4gp .030 quench with iron heads, 9.98 comp and 8.3 or so dynamic and 28 total timing on 91 chevron.
Did the testing and checked everything to know.
Dartsun
Mopar Dude
The Brisk spark plugs are pretty good from what I've read. Lots of guys use them in the cranked up turbo Audis.
TimS
Well-Known Member
Well I’m over cleaning soot off the NGK 7’s and a crummy running motor. Time to try some 5’s.
TimS
Well-Known Member
I find it odd though that it seems I'm going in the opposite direction with the plug heat range according to the NGK chart. This would be on the hot side for a standard/stock engine. Really hot for a high compression engine. I should be up in the 8-9 range.
NGK Spark Plug Heat Range Chart
Heat Range Application
2–4 Small engines (lawnmowers, generators)
5–7 Standard passenger vehicles
8–9 Performance vehicles, light racing
10+ Extreme performance, heavy-duty engines
NGK Spark Plug Heat Range Chart
Heat Range Application
2–4 Small engines (lawnmowers, generators)
5–7 Standard passenger vehicles
8–9 Performance vehicles, light racing
10+ Extreme performance, heavy-duty engines
340six
King Of Bling
My B&S small engines came with 5 same size plugs as recomm nd for many small blocks and stroker motors.
My larger Honda Generator has NGK 6 one step cooler
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TimS
Well-Known Member
I'll throw some new NGK 5's in today and see what happens.
HuntedDuckV351
Well-Known Member
R5671-7 on E85
TimS
Well-Known Member
Got the NGK 5’s in but haven’t started it yet. Those 7’s I took out, I cleaned over the weekend, are already sooted and wet with fuel after only about 10 miles of driving.
Do you think they figured fuel type being used, fuel is a major factor in determining heat range and plug gap.
I have been running -7’s in my 340 for a few years. After pulling the plugs a few times in my now 340/420, I decided to order the -5’s after seeing a lot of buildup on my plugs. I used to run the -5’s when I ran iron heads, but was told to run the -7’s when I switched to aluminum. They should be here next week so I will throw in the -5’s and see if they clean up a bit.
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