Currently running NGK R5670-8 race plugs and was thinking about going a step colder as I have a little bit of a dieseling problem I haven't be able to get around with carb tuning (King Demon Dominator)

11.5:1 on pump gas (timing pulled)

 

the plug color is what to go by. my dad allways said, plugs are cheaper than pistons. 11.5 on pump gas? you know better than that.

 

Pump gas?? with 11.5 compression. your probably getting some predentonation or the carb jets are to lean,try putting some bigger jets in to help cool things down.

 

I actually went with stock heat range NGK's and was able to bring the idle down a bit more, so I don't have the dieseling problem anymore.

Seems the colder race plugs were getting fouled at idle.

Going by the condition of the new plugs after a week, it seems she's running a bit on the rich side, so I'll be jetting down a bit when I get a chance.

 

Personally i have always had great performance with Champions and i think they perform better in old school carbureted mopars i ran some once and notice a big difference in all around performance.
I agree with Zoomer richen up your jets.
if your getting run on it's, a sign of a lean condition.

 

I'm not even gonna ask why you would want to run pos ngk plugs in anything. Personnally I have no idea why the company isn't bankrupt with such a crappy product.

Put in some champions and be done with it.

 

I don't want to get into a debate on plug brands as everyone has their own opinions, but this is actually the first time I've ever heard anything negative about NGK's

On the other hand, I wouldn't put Champions in my lawnmower

 

i think they work better in those asian cars... thats why they haven't gone bankrupt. but for old school i always run champions.

 

On the other hand, I wouldn't put Champions in my lawnmower [/QUOTE]

Lmao tooooo funny !!! As to a bad ngk note I had a year old ngk plugs ground rod or strap fall off in my 1200cc pwc !!! Smoked the cylinder

 

I hope thats not 11.5 on pump gas with iron heads,, If so that thing is a ticking time bomb.

 

Are you saying that iron heads are explosive?
so he has to back off the timing on pump gas
my brother ran 11.25 on pump gas for years and his iron heads and or motor never exploded.
quit paying attention to these false flag presser cooker propaganda pieces on the main stain news.
If they get wind of this they will start to confiscate high compression Explosive motors. LOL

 

Suffice to say, there is a most definate difference between what is called "Pre-Ignition", and "Detonation", and far too involved to get into here.
No matter,
a true static C.R. of 11.5:1, on iron heads, using pump gas(92 Octane), depending upon Camshaft, will most probably, eventually, Flake the Bearings and destroy itself NO MATTER what the Timing is backed off to.

Let me guess here, does it seem to run " hot" alot of the time ?

 

Ive played with any engine from weedeaters and chainsaws to snowmobiles and motorbikes both on and off, as well as vehicles up to 5 ton trucks.

Ive seen ngk spark plugs dead from new far to often. Once out of a box of 50 there was only 18 good, tested on a coil and stator with 1/2 inch free air gap jump. In 30 years I have had exactly one bad champion out of the box.

Hence I ONLY run champions in anything I own and guess what not a single problem even after years of driving.

Now I have encounter this before where people say they get champions manufactured in mexico or some such and have problems. The ones I usually get say made in Canada so that might have a difference.

NGK as far as I know are all made in tiawan so the quality is going to be bad.

That said anything over 10.5 compression should run 110 octane which is NOT available at pumps. Your going to get ping on anything less than 110 octane and spark plugs wont make a difference.

 

Here in sunny florida we have both 101 110 Sunoco stations carry it also the local marinas have real gas and our premium is 93, which if i run any lower i get detonation.
i have never gotten a bad plug... only run champions but i tried these bosch platinum once, they didn't perform any better than the champions. i think the champions can handle higher voltage than the bosch.

 

Just a suggestion..unrelated to any run-on problem, but,
you may wish to find a Champion "Performance Plug" Catalog, and find some of the "C" series Champions for your particular application.
The snap KV on those "C" Series Champions, back when we tested, against NGK, Bosch, V-groove, Platinums, blah, blah, anything that we could lay our hands on at that time...
was as good as, and usually better, than ANYTHING, across ANY Firing Voltage even at very High Cylinder Pressures.
I am NOT saying the "regular" Champions, never tried them so I dunno...but the C series are top drawer plugs.

 

Why even have that that compression and try to run todays crappy gas and jack the timming all around to justify being a tight wad. My point is you can you can push the limits a hair more with aluminum heads over iron. Aluminum heads dissipate heat faster. Rule of thumb you can run a point higher on pump gas over iron heads. Todays gas building engines claims 9.8 max with iron and 10.8 max with aluminum on 93 octang. My question is to you what was his total timming set at ?

 

First off, I didn't build the engine

This is the way I got it, so I'm trying to make the best of it.

No, I can't afford to run race gas all the time, but she seems to run just fine with the timing pulled on 93

If that makes me a tight wad, then so be it

I'm actually proud to say I have absolutely ZERO money into this car (started off with a golf cart and traded my way up on Craigslist) and I don't plan on spending any money on aluminum heads or anything else motor related unless I have to.

 

Buy some octain booster, NOS off road works good you can get it at autozone. Total timming is more important than idle timming check that.

 

Snake,

I'm with you. I bought a '69 RR with a 440 stroked to 496 with 13:1 compression and aluminum heads. Puts out just over 700hp at the fly and runs great on 105ish octane. We have 100 and 110 here in N. California. I took the car for a 40 miler last weekend and the engine temp went no higher than 175 degrees on the highway and 192 on the street in traffic in 92 degree weather. I also use octance booster from Torco which can raise the octane 11 points on 10 gallons of fuel.

You can run a higher compression just compensate with higher octane!

By the way, I pay $8.29/gallon for 100 and $8.99/gallon for $110.

 

I've found that Toluene works much better than the off the shelf booster stuff, but the prices have recently skyrocketed thanks to all the terrorist and their homemade bombs

Timing is locked out @ 30* for pump gas

My local station used to carry 100 and 110 (Sunoco brand at a Mobil station) and sold both for the same price, but recently switched the 100 to 91 Ethanol Free since most folks went with 110 anyways.

 

OK, a little update.

I went with NGKR5670-7 as per ManciniRacing's suggestion which actually happens to be 1 step hotter than the plugs it came with and surprisingly, I no longer have issues with run on

Idle quality has also improved