Being my car prob has the most in common with ppl in this section, I figured I'd post here. I have been having an issue with my car pinging if I go over 31* total timing or if I lean it out more then 11.5 AFR at WOT, Engine has 11:1 compression . I know I should be able to run 34-36 total timing and 12.8 AFR. I'm starting to think I'm running to hot of a plug(NGK 2460-BKR5ES) its a 5 heat range(heat range gets cooler as the range number gets higher). I made a few call to day and had a few different plugs suggested. I called NGK and they said go with there 5534 in a 7 heat range. Summit said to go with a NGK 4554 in an 8 heat range. Last I called Brodix who make my heads and they said to go with an Autolite 3924 in a 7 heat range. They told me not to go with a 8 heat range unless I run race fuel but I run 93 octane. So just wondering what plug and heat range you guys think would be best?

I'm running NGK heat range 5 in mine, I get a little pinging but not to bad. Yeah, I thought about running a colder plug in my car but I just don't think it's necessary to run anything colder than 6, unless you're running nitrous or boost of some sort.

Well its pinging a lot with more then 31* or leaner then 11.5 AFR at WOT.Both Brodix and NGK told me to go two ranges colder from 5 to 7. When I had the engine built last year it did the same thing and I didnt pay attention to the pinging as I should have and the pinging/heat wiped out my valve guides in 400 miles. I checked geometry , everything was spot on.

What kind of fuel pump are u running in your car? Have u tired putting higher octane gas like 110 for example to actually see if ur car needs more octane I doubt it. Its worth a shot, I know my 383 needs to run on a mix of 93/110 but my motor is 13.1 compression alot more than yours.

I run a 255lph Holley fuel pump.

I was just reading a car craft online article on that today:

• Compression ratio: Increasing the mechanical compression ratio raises cylinder pressure, resulting in higher cylinder temperature. The higher the compression ratio, the colder the spark plug needs to be. According to Champion Spark Plugs, for normally aspirated, gasoline-fueled engines, a good rule of thumb is to go about one heat range colder for each full point in compression ratio increase from 9:1 through about 12.5:1, and two heat ranges colder for each point increase between 12.5:1 and 14.5:1. Beyond 14.5:1, 3-4 heat range reductions per point may be needed.

They were also saying its better to go to cold then to hot. To hot, like the plugs I have now can cause detonation/pinging and engine damage. Too cold and it will just foul a plug but wont harm the engine. So with the Car Craft article and NGK tech both saying the same thing I'm going to try The NGK BKR7E-11(5791) 2 heat ranges colder then the hot plug I have pinging in the car now, being I ran the old plug in the cars stock form vs the cars present 11:1 compression -2 compression points higher then stock.

Yes car craft is right on that I run a ngk plug #4091 in my 383. Your sure your not running out of gas in the upper rpm range I know mine was even though it was showing a 12.5 afr up to 5500 and I was draining the rails with a single 255 pump I added an inline msd pump on mine and it fixed that. Have you tried hooking up a fuel pressure gauge and taping it to the windshield to see if your fuel pressure is dropping? Try the colder plug first that's what I would do. Unless your motor is just that effecient lol

I also see your running 30lb an hour svo injectors u might be maxing them out, your sure your not making them going static it is possible your motor is making enough power to need a bigger injector. Only other option is to throw some race gas in it? Just trying to help man because if you ping the motor alot eventually you will knock the bearings out of it.

I'm running the 30lb injectors at 60 psi so they are equal to a 36lb injector at 40 psi which would cover my fwhp. I'm not pinging now even at WOT, but I would if I leaned it out more then 11.5 AFR at wot or if I put more then 31* total timing in it. I'm going to go 2 heat range cooler on the plugs and see if that lets me lean it out closer to 12.5 AFR at WOT.

Damn that is alot of fuel pressure,but try the plugs first it wont hurt anything that's for sure. Then if that doesn't help enough then try the race gas. But really you shouldn't have to since your motor is only 11 to 1 all the plugs look good otherwise no oil on them? Something doesn't seem right what rpm range does it start to ping at?

yeah fuel pressure is alittle high but i've spoken to a lot of ppl about it and seems that it should be fine. pretty much the same fuel pressure LSX cars run at. Yeah, being NGK and Champion are both saying I should run a two heat ranges cooler spark plug I'm sure it can only help if not totally fix my issue. Rather that fix it then going to race gas. no oil on the plugs, and it not pinging at all now with the 11.5 wot afr and 31* timing. If I leaned it out or put more timing in it would ping around 4400 in 2nd gear. plan is to put the colder plugs in and then start to lean the wot afr to mid 12s, if that works without pinging i'll try alittle more timing.

Cool toss those plugs in and let me know if it fixes it.

Keep us posted on what happens, I might need to go to a colder plug also. I got a little pinging myself......

Spoke to NGK again and they told me to def go 2 heat ranges colder. They said to use BKR7E (4644) comes gapped at .035, BKR7E-11(5791) comes gapped at .043. Just let it idle for a few mins before and ran good. Its raining so I'll have to hold off leaning out WOT AFR a couple days but I'll let you guys know if I was able to get it leaner with the colder plugs.

update. Just a reminder I was having pinging with more then 31* total timing and if I went leaner then 11.5 wot afr. So going two spark plug heat ranges colder from a 5 to a 7, I first subtracted 5 from the PE vs. RPM table above 3600 RPMs..took it for a wot run in 2nd gear from a low rpm and the AFR then was 11.7, no pinging. Then I added 3 degress giving me a total of 35 degeress. I did 2 more wot runs and the added timing leaned it out to around 11.9. I didnt hear any pinging and with that same tune last week with the plugs two heat ranges hotter it was pinging like crazy. Looks like rain so I'll have to do a few more WOT pulls in 2nd and 3rd tomorrow and make sure it still not pinging. If that works I'll lean out PE vs RPM some more and hope to get closer to 12.5-12.8 AFR

Is it feeling stronger ?

Whats the knock sensor showing? Any timing retard? Its highly likely the knock sensor is gonna pick up something before you ever actually hear the pings. Atleast, thats what its suppose to do

I have the knock sensor off...it was giving me a lot of phantom knock counts and pulling timing even when it only had like 24* total timing and was 11.0 wot afr.Last time on the dyno I gained 57 HP just from turning the knock sensor off, the car def feels stronger. I'm just listening for pinging and watching the WB AFR guage. I dont plan on going over 35/36 total timing and 12.5/12.8 AFR
I found online that every NGK heat range change is 100* C or 212*F, so me going two plugs cooler is around 424*F
****Think I'm just going to take a few degress out and run 32* total and try to see if I can lean it out to 12.5, see how the car likes that for a while

Just curious, do your plugs have a tapered seat, or do they have the washer on them? I don't think that plug will work for my heads, I need the tapered seat.

they have the washer and I dont think they are tappered... Give NGK Tech a call and they will tell you a plug for your setup...1.877.473.6767

Yeah, probably should......I'll do it tomorrow. Thx.

They should have a tappered seat plug

Yeah, I'm pretty sure they do. For some reason my NGK chart that I printed out did not have the plug listed.

If you guys know the part number, let me know......

So I'm running a hair over 31* total timing and the AFR leans out to 12.5-12.7 at WOT. I dont hear any pinging as of yet so the two heat range colder plugs made a hugh different. I must be a little slow taking over a year to figure out the pinging.

awesome glad to hear you got it lined out a little more.

get it back to the dyno

When I build a motor, I focus on the quench. My block is zero decked and I'm using a .040 head gasket. I run 93 octane and 37 degree total timing without any pinging on my 11.0-1 compression 406.

If your shortblock was built with the piston say .020" in the hole and you're using a .039-.041" head gasket, the quench is going to be around .060". This will make the motor very sensitive to fuel. If that's the case, the best way to solve the problem is to pull the top end and change the head gaskets. This may not be what you want to hear but it may be the only way to truly solve the problem and get the motor performing as it should.

Orr - What's your opinion?

I agree with the quench height being important but its also has to do with combustion chamber design and as noted here, spark plug heat ranges.

My 383 was zero decked and used AFR heads.. I ran a 6 heat range plug, tight gap for nitrous, and had about .041" quench height. I ran it lean and high timing, as much as 39 deg searching for power and never had a ping or spark retard from the knock sensor! I eventualy found 34 deg to make best power and torque, so I left it there. Air fuel was around 13.0

I dont think my car would have liked a 5 heat range plug and from what TPI-Formula says above, he thinks the 7 heat range plug cured his problem. I had a slightly bigger cam tho which would have lowered dynamic compression and cranking compression, so that would be less sensitive to fuel/timing.
Spark plug heat range is something thats often overlooked and can make a difference. But you just have to experiment to see what your heads want. Different chambers can have different burn patterns/rates, much like how vortec heads only run 30 deg timing most of the time while other heads may need 36.