Read this spark plug for me please?

[dstryr]

I've been struggling with my stroker motor fouling plugs and generally running poorly.  I think I'm finally getting some learning through my thick skull and figuring out how to tune the 6bbl setup.

#66 jets in the center, 81s outboard, about 16* initial timing and stock carbs except for jettable outboard metering blocks.  It runs a little hotter on the gauge than before but I don't have a gauge to give actual temp, just the factory one.  Oil pressure ranges from about 70lbs at 3000 rpm down to high 50s as the water temp climbs.  As the water temp drops, the oil pressure heads back to 70ish.  Idling @ approx 1000rpm I have around 25lbs pressure.  Well, that's more info than necessary for diagnosing plugs, but maybe a detail will give someone an idea about what I might do next.  Dyno tune had 83s in the outboards and when I drop the hammer now seems a little off, maybe too lean.  

What do these pics say about my tune?  All the same plug, the other 2 I took out look virtually identical to this one.

TIA!

[A383Wing]

how many miles are on these plugs?

Looks a bit "too white" to me....which means running a tad lean

Bryan

[dstryr]

maybe 300-400 miles.  The fronts fouled after getting some help last summer and the front carb idle screws were way too far out so I just fixed that and felt like it ran and idled better.  I drove it maybe 15 miles a couple of nights ago and then probably 40 tonight.  I'm only a couple of blocks off the highway so didn't idle home and tried to keep the RPMs up until I shut it off.

It does seem like I'm getting a lean miss when I'm on the throttle hard, but like I said before, I'm not good at diagnosing some of this stuff- just not a lot of experience with a good motor.  Most of my cars have had worn-out motors so reading plugs was just seeing how bad the oil fouling was. 

[dstryr]

I had NGKs in before for the dyno and breakin miles which had a more shrouded insulator and electrode.  Maybe go back to the colder plug? 

[Brightyellow69rtse]

i say lean

[histoy]

Looks lean to me as well.

[heyoldguy]

With unleaded fuel, the fuel ring you need to read is way down where the porcelain meets the metal.

So unless you shine a light way down in there to see the ring on a fresh plug with a "burn clean" run you'll not really know what is going on. Reading the top of the  porcelain around the center electrode is generally useful for checking for detonation but not for fuel mixture. For a plug that has been running around on the street for awhile, it looks pretty good on fuel mixture.

What is your total timing? I think I would go to a colder plug or back out the timing.

[firefighter3931]

I had NGKs in before for the dyno and breakin miles which had a more shrouded insulator and electrode.  Maybe go back to the colder plug? 

Frank, based on the ground strap's appearance i'd go to a colder plug. I ran the NGK 6 series in my E-headed 446 with 10.5:1 static comp with excellent results. 

As for jetting it does look slightly lean but not too far off.

Have you seen this 6-pack tuning guide 

http://www.moparts.org/Tech/Archive/fuel/7.html




Ron

[Charger 512]

U should be looking at the bottom of the porcelain,cut the plug with a zippy cut and have a look at it

[dstryr]

Still something amiss, though I think the carbs are pretty close.   I put my dial-back timing light on the engine and at 4000rpm can only get 26* timing total.  The springs are good, weights are lubed & good, the breaker plate rotates freely when the distributor is apart.  I set it up with 16* initial and should get approx 36* total, which is how it dynoed. 

For reference, it is a stock Prestolite dual point distributor with a Pertronix Ignitor module.   Something is now preventing proper advance.  Any ideas?

[Paul G]

Are you using a multiple spark ignition unit? If so a dial back timing light wont work on it.

[dstryr]

Paul, I'm using a Pertronix Ignitor and Flamethrower coil in the stock Prestolite housing with a tan cap and Firecore wires.

Still seems to not be advancing so I want to check it with another dial-back light and make sure its not my timing light. 

Also in reading up on the symptoms see that it could be valve float.  I did not upgrade springs when I bought these heads and am running an XS290S cam with .540/.558 lift and reading search results about the issues I am having point to possibly having valve float. 

Would you guys expect the stock Stealth springs to crap the bed in a couple of thousand miles?   

[Paul G]

I think that timing light should work. I know my MSD box would not work with a dial back light.

Does that distributer have a limit adjustment on how much mechanical timing it will allow? The adjustment will be on the advance plate limiting the amount of travel and  mechanical advance timing.

[dstryr]

There is no mechanical adjustment, just the vacuum and mechanical advances on this vintage distributor. 

[firefighter3931]

Pull the distributor and see why it's not advancing properly. Look at the weights and make sure that they move freely. My guess is that the weights are somehow frozen/binding or there is an issue with the advance springs.

The Valvesprings in those heads are the same as the Eddy RPM's so you're fine there. I ran a .580 lift Custom solid that was more agressive than the XS290S with the stock RPM springs. Buzzed it up to 6500 several times with no valve control issues. 


Ron

[Paul G]

This is a dumb question, are you using vacuum advance, and if so is it disconected when you check your timing?

[dstryr]

Unplugged, yes, and capped at the carb.  The diaphragm is shot. 

Ron, I've had the dist out a couple of times.  All seems very free with no binding.     I'll pull it again and have a look for interference marks on any of the pieces.

[AirborneSilva]

I think that timing light should work. I know my MSD box would not work with a dial back light.

What do you mean by dial back light?  I have an MSD box and can't time my motor with my light, it bounces all over so I was thinking that it was an issue with my distributor since it's an old one.

[Paul G]

 

I think that timing light should work. I know my MSD box would not work with a dial back light.

What do you mean by dial back light?  I have an MSD box and can't time my motor with my light, it bounces all over so I was thinking that it was an issue with my distributor since it's an old one.

Does your timing light have a dial on the back of it or a digital display with buttons?  If so it is designed to dial in the amount of advance you are getting at your desired rpm.  Multiple spark discharge ignitions make an advance light go nuts. I learned that last year with a brand new advance light from Summit. have to use a standard timing light with an msd type ignition.

[AirborneSilva]

I think that timing light should work. I know my MSD box would not work with a dial back light.

What do you mean by dial back light?  I have an MSD box and can't time my motor with my light, it bounces all over so I was thinking that it was an issue with my distributor since it's an old one.

Does your timing light have a dial on the back of it or a digital display with buttons?  If so it is designed to dial in the amount of advance you are getting at your desired rpm.  Multiple spark discharge ignitions make an advance light go nuts. I learned that last year with a brand new advance light from Summit. have to use a standard timing light with an msd type ignition.

Yes I do believe it does have a dial on the back, I got frustrated with it when it was all erratic and just timed it by ear.