another plug read

just pulled the ngk7's after running on a mix of race fuel. combination of around town, freeway and some full throttle blasts. Gonna try some champion rc9yc in it. Comparible to a ngk6.

It's rich.

??? WOT run it to the middle of 2nd gear (auto), kill the engine, pull over, and pull a plug. This tells us nothing.

If the bottom pictures is of the NGK6 they are to hot
If not
How much total timing are you running with these pictures?

well, i can tell ya this. wide open on my wide band reads 12.5-12.6. very safe there. Thats way more accurate than reading the plug. Plugs are just too hard to read.

no, they are all 7's and timing is all in at 36* now with the race gas.

It may be fine at WOT but that thing is pig rich at a cruise and I'm not going to say you are correct at WOT until you kill it clean and cut the plug apart.


I don't care what the A/F meter says that thing is pig rich at idle and cruise. Do I need to post a picture of what a decent tune up looks like? I trust my ability to read a plug long before I trust that gauge. That's for damn sure.

It's PIG rich.

ok, than. it may be pig rich, but it sure does run good pig rich. sounds very happy. I might try putting the t slots back to .055 from .059 and see what the results are there. That did richin things up a bit. Thanks guys

Can you post a plug with a proper tune? I really would like to see it. The camera makes them look darker than they really are. They are dark grey in color. What part of the plug are you looking at that says pig rich to you?

I will go out in the morning a grab a couple. They should be white.

Hope I can figure out how to post a picture here. I've never done it. I may have to email them to you and let you post them.

FWIW Wallace racing has good plug tuning pics/info.

cool. where ever you get a chance. cudadave@outlook.com

I think plug reading with street driving and pump gas is going to be a waste of time. If it feels happy and good roll with that. You are going to have poor distribution at low load and overlap and reversion further messes things up. Your intake isn't designed for putzing around town, it is designed with a RPM range in mind, when it is running in that range distribution will be way better.

Yup.

I get the best plug colors with 14.5 AFR or leaner(up to 15.5 AFR cruise or idle) at idle and light part throttle cruise RPM below 2500 RPM
I agree with the mad scientest on plug colors, white to very light tan is perfect
Dominic and I have seen the same thing your seeing and feeling with the AFR rich, richer feels good but leaner is meaner except at WOT

I just sent Dave three pictures of plugs that came out of my car to post. As soon as Dave gets to it, I'll post some comments.
Thanks Dave

Kinda how I approach it these days with the WB being a directional tool more than locked in stone........

Pics sent to me.

I’d be very surprised if a combo like Dave’s actually drove well with the a/f meter reading hi-14’s to lo-15’s.

For part throttle operation I get them to drive to my satisfaction, and whatever the a/f ratio is..... so be it.

Yep. Runs like crap cruising at 2500 and below rpm. Sounds like misfires. Lean misfires? Cruises best in the 13.0 to 13.8 range.

The middle picture has plugs I just pulled out this morning. You can see I'm still a touch rich at cruise with just a quick look. The porcelain should be a dull white.

The bottom picture are a couple of plugs I pulled and cut apart last summer. You can see tha shading on the upper part of the porcelain so I was still a touch rich, but if I went much leaner at a cruise I had a tip in issue. So you have to compromise sometimes.

In the bottom picture, you can see the fuel ring is better than .125 wide and has what I call a fade to it. IOW, as you move away from the shell, the fuel ring isn't well defined and fades into the middle of the porcelain.

The fuel ring is WOT. Depending on what you are doing, you can get as tight as a .060 wide ring with race fuel or alcohol. You need to be .100-.110 wide on pump gas. And no fade. The fuel ring should be sharp and clean with no fade.

This is an iron head, 11.01:1 pump gas 340. I have a Racer Brown solid flat tappet cam that is 281/281 255/255 .620/.620 on a 105 LSA in at 105. The intake manifold is a fully ported Holley Strip Dominator (I did the plenum back to square by welding it up and did a little welding in a couple of other places...wish I had done more welding) with a 1.437 Venturi BLP B4X carb.

I run Hooker 5303 headers with custom craft mufflers. I also run a Mallory Unilite with the curve locked out and the total at 36*. I also use a Mallory 685 digital ignition box. The plugs are Champion.

That's all I can think of right at the moment.


THANKS DAVE for posting the pictures for me. Hope this helps.

Exactly, EFI maybe but with duration and overlap my Dart falls on it's face when mashed cruising in that zone.........been there, done that........

No problem. Thanks for explaining plug reading. Im gonna try going back to the .055 t slot from the current .059. The .059 was put in to cover a lean tip in which turned out to be fuel and heat related. The .059 did richen things up a bit. Gonna try the rc9yc champion first just for shits and giggles.

With good fuel you MAY like a .052 and don't put all of your faith in the WB like people are saying, get it right and the numbers are what they are......

Ok. The race gas did richin it up a bit. Ill try the .055 first. Ran good with those and go from there. Thanks Dom.

Plus when I ran leaded gas it liked more timing........

You want to stick with 1 fuel grade till you learn the spread from each fuel on jetting.I did a couple 60' launches in my drive and read my plugs till I move on to the next step of jetting.[add pv]I have #7 plugs in.

What fuel are you using and what plug is that?

NGK-7 with pump 93

ok. looks like the the plug in the pick needs to be next step hotter. color change is near the end of the ground strap. I have some fresh plugs in it now. i will see how these color up.

I wouldn't put much stock on doing what you did in the driveway with the accelerator circuit furnishing a lot of added fuel to the launches
I would go drive it at light part throttle now to see what it is running like on the idle and transition circuits and go from there
I would use a G meter or the sixty foot times at the track to tune the accelerator circuits, not how the spark plug looks

I agree and I want to see what his look like with newer plugs side by side when he does.

Me too

What tool are you guys using to cut the plug, in the above pic the cut is nice and clean.

I did that in my lathe here at the shop.

You can do it with a right angle grinder too. You just need to be careful not to get into the porcelain. At least don't hit it all the way around.


This made me think of a customer I had. He would use a hacksaw at the track when he was picking the fly poop out of the pepper. He made a fixture to hold the plug and just got after it. He could do a plug in no time.

You can do it any way you can think of. It doesn't matter how you do it. Just that you can get the shell off and leave all your fingers on.

Thanks, was wondering if someone made a tool to cut the plugs.

I bought a 10x magnifer glass off of a small dental medical tool, that really helps to look closely at all of the spark plug, especially the ceramic insulator below the spark plug body

I light is fine. But when you are trying to measure the fuel ring it's impossible with the shell on.

I called my customer last night and asked him how he made his jig to hold the plug.

He says someone now makes one that clamps on to the bumper. He did give me an on the cheap way to grab the plug to get the shell off.

He says just use an old spark plug socket and grab it in a vise. Cut through the shell and then grab the plug and turn it one flat and cut some more.

There is no reason not to cut the plug apart.

Havent had much time with the car this week, but did take a cruise out in the country, about 25 miles mostly cruising at 3000rpm with alot of stop and go and a few wot blasts. Still on the 110/93 mix and using champion RC9YC plugs. When they start coloring up i will lean the T slots at that time and see if they clean up at all. Engine ran fantastic with very good street manners whole short trip. Only pulled 3 because they all burn the same except #7 which is on the far left.

Thanks for posting.

Hot damn. They are looking pretty damn good. Now you have to do some WOT and cut the shells off so we can see that.


NICE!

Those look really good to me from here
I wish it had been all light part throttle cruising with no WOT blast though
The pencil looking colored line on the ground strap that I can see looks good also
Now put in one new one in #7 and go get after it for a 1/4 mile right away and pull it out before driving it anymore and post the picture of that one

they do look very clean. Im not seeing the color change on the ground strap though as these may be to hot. I will see as i run them. Wont be able to get to a track til end of sept, that would be a good plug test if i could. When i do go i have a set of champion race plugs with the cut back ground strap(c63cx) i would like to try.

The cut back strap is for piston clearance no?Do you like the Champion brand plug over NGK?

Just trying the rc9yc as i used to see a few racers on here recommend that plug. Thought i would give it a try. Back in the 70's as a kid i always used champion plugs in my dirt bike. They lasted longer without fouling than the ngk would. Didnt chryslers used to come from the factory with champions in them? Ngk got there crap together and now make a good plug and their cheap.

Some have said the cut back strap makes a few more hp on the dyno. I cant confirm. Indy cylinder head recommends them as well.

A friend of mine who ran NHRA stock would cut back his plug ground strap to expose the spark to the motor
I didn't, I had some colder Champion race plugs that where that way also He set several NHRA stock class records, I didn't

This made me LOL real hard!!!!!!^^^^^^^^^^^^^^^^

My folks bought my first dirt bike for me in August 1972 (damn near caused a divorce because my mom didn't want me and my brother riding dirt bikes...we already playing tackle football and did all the crazy things we did back then...but I held my ground and won out) and that's when I started learning how to read plugs. It's been a life long learning experience.

I've read plugs on everything except injected nitro and blown nitro. When we were old enough to ride with our friends and the old man was too old to ride, I started asking anyone riding with us what bike they had. That way I could buy a Champion plug for the bike. I'd tape it to the handle bar. Sometimes I'd have 3 or 4 pugs taped on the bars.

You just KNEW one or two of those guys would foul a plug 25-30 miles from the truck. They'd be pissed, and say that was a brand new plug for this ride. Id swap in a Champion and we'd finish the ride.

Back at the truck, I'd make then pull my plug and give it back.

That happened more times than I can count. I've been using Champion plugs since 1972. I no longer ride, but my brother still does. And when he rides with people he doesn't know...he brings Champion plugs for them.

I can read NGK plugs, but I'm not a fan. If you are paying me to do your tune up, we start with a fresh set of Champions and tune from there.

Hahaha, yep good old memories. Golden spectro and klotz technoplate, man that stuff smelt good. The champions burned right thru all that oil.

1 of Doms ngk8 with 5 months+ some miles and a few tested carbs.

Dom has his [censored] wired tight. That's a nice tune up.

Not bad for a "non street-able" Dommy street car with 276-281 @ .050 .680-.660 Isky solid roller at 470 cubes............Duration is your FRIEND, don't be afraid of it and hang on............

Thankxxx for posting this and the post about the 505 ci street car and his concern with drive-ability and mileage needs to see this..........The street IS the equalizer, not theories or 200 dyno sessions but actually driving these things and seeing the results instead of PREDICTING what you think may or should happen.............

Sure....... now put in a 3500 converter, OD trans and A/C along with probably 500lbs additional weight........is the 276 cam still the best choice?

And I get that but have customers running a bit less than me but the 500+ cubes and even 3.55's and tighter vert's are no problem for them trust me. for the op about the 505 stroker deal, I think he might as well buy a modern heap since he wants EFI and economy BUT may hit the track a few times a year......To each his own but you guys are turning a potential beast into a tamer than it needs to be deal and just seems like a waste in some ways by building big and tuning small..........