atlantadan

Context: ERE 383 w/TrickFlow heads with about 7k on it. Pistons are hella noisy due to piston alloy, short skirts, and some other stuff. Karl is building me another shortblock with tighter clearances and different alloy pistons, but until that gets here, I want to dig-in. Slap decreases a lot once warm, but still always there somewhat. LT4 knock module. 2.93 gear. 3k Yank stall. CIA headers and CIA high-flow cats - cats have at least 5-7 years on them. Car spends 99% of its life in light-to-light, sub 45 mph city driving (Atlanta. Yay). Car doesn't eat coolant at all (this will be important later...). 12-13 MPG in town with a lot of sitting in traffic. Honestly don't know the hwy MPG's since I'm never on it.

I've been chasing down some knock-counts (with the assistance of Moe Bailey) with this car and in the process have started testing different heat-range plugs. (Karl thinks the knock-counts are due to the pistons, but there were times in the summer where I thought i could hear some detonation, so I started to look elsewhere.) I was originally running the OEM heat-range on 11.4 CR, gapped to .040. Car ran great, but the knock counts were still there in the logs and my NOx was a touch high due to high combustion temps. Not enough to bomb the smog test, but really really close. When I pulled the plugs, they'd been running for 7 months and all looked pretty good. No soot, porcelain a nice grayish/brown color. No soot on base-ring of plug, nor on the ground strap. No signs of detonation - plugs looked clean and completely serviceable, but in the interest of testing, I called NGK and told them all my mods. They suggested dropping down two heat ranges, so I did - BKR7E's went in, gapped to .035.

The car started to miss on hot-restart within about a week. Pulled the plugs and the ground straps were white, with black electrodes, and wet looking black all around the base-ring of the plug. Porcelain was stark white. Some Google-fu'ing yielded very few results of white ground straps, but among them was talk of white being coolant deposits. So, repeating above - the car does not eat coolant at all, so there's that. Others said that a white ground strap means its running way, way too lean, but the logs don't show this to be the case.

I increased the heat-range by one to BKR6E's (so one colder than stock) Gapped to .035., and motored on down the road. Within about 2 weeks, the car started to miss on hot restart. Got to the point where it flat-out would not clear up after driving. Pulled them out last night and more of the same - wet-looking black around the base threads and base ring of the plugs, white ground straps and porcelain.

As of last night, I popped the original heat-range Autolites - new ones - in there, gapped to .040.

Anyway, I guess the question in this wall-of-text is regarding the white ground straps and fouling. Both sets of plugs had run about 1-2 weeks, so they only had about 150-300 miles before they started to give me issues with fouling. The Autolites went about 7,000 miles and are shown below. Does the car just want the OEM plugs due to doing lots of low-rpm around-town motoring? Whats with the white?

On to the pix. Crap on the threads is anti-seize
BKR7E on the left - 200 miles, BKR6E middle - 300 miles, Autolite 1601 on the right - 7,000 miles.


Top view:

hrcslam

Looks like the left one is the correct heat range. But the timing is too far advanced. I'd try the left ones again and pull timing, then adjust AFR and timing until it's tuned in properly.

Nostang

iTrader: (4)

I agree with hrcslam on the left one looking like the correct heat range. It is clean and looks like the timing is a little high but not too terrible but it is hard to tell by the pics. You could also try some autolite 3924 race plugs and see how they perform. You will need a hotter plug for street driving than you would for drag race only for sure.

BALLSS

as you went to colder range, with very few miles on those two choices, looks like each cooler range there is more oil/carbon on the base of the plug vs the 7k mi stock heat range ones

My 383 11.3 I run TR55 at .045 gap....beautiful tan color, no black build up on the bottom of the plug

If you had stumble on the cooler range ones within a few hundered milesand were fine on the stock range....I would go back to what you have

you using some kind of fuel additive or octane booster??

hrcslam

Ground strap is used for timing. The threads are used for heat range. Ceramic is also used for timing. Carbon build up in certain areas is for AFR.

If you look at the ground strap on the left one the Mark is all the way at the base of it, it should be right at the 90° bend. The threads are darker (less shiny) for the two closest to the ground strap, which is exactly what you want.

It looks like the left one is the correct heat range, but it has too much timing advance put in it. Adjusting the timing will affect AFR, so you may have to adjust that too.

If you could data log with the left spark plugs in I wouldn't be surprised to see the BLMs being off.

atlantadan

Thanks for the info and setting me straight. Now for the million-dollar question: how much timing to pull? Is this a trial-and-error sort of thing or is there a baseline that I should try first?

Will adjusting the timing down help with fouling or is that where the AFR comes in? I suspect its a combination of the two...

Thanks again, everyone.

Nostang

iTrader: (4)

For setting timing I like to run the car at the track to find the optimal timing that mph's the best. If you are mostly cruising around on the street and not worried about best hp, I would 2-4 degrees in the rpm/map range you are in the most and leave the rest of the table alone. The reading of spark plugs is best done with brand new plugs and by shutting off the car at WOT at the end of a quarter mile run to get the snapshot of the greatest load and working off of that data point along with your best mph.

Casey96SS

You can pick up a cheap otoscope on Amazon for like $20 to take a closer look at your plugs.

http://rehermorrison.com/tech-talk-8...e-your-engine/

hrcslam

I'd pull a couple degrees in the area you drive the car in the most, check the datalog for AFR and adjust as needed. Then read the plugs again and repeat until the timing mark is at the right spot on the grounding strap.

Of course a dyno tune would be faster and easier.

I'm not sure what your build specs are, but my spark timing table looks like a double hump. Runs and drives great that way.

KW Baraka

iTrader: (7)

I'll bet you $20 if you went with more gear (3.73's) and lest stall (2400-2600) your city MPG would improve considerably.....and you'll have a car that's easier to drive in traffic as well.

No need for highway gears if you don't do a lot of (or any) highway driving.

No need for a race oriented converter when you don't race.

Jus' sayin'.

KW

atlantadan

Update: While driving it around yesterday, the car started to miss again on hot-restart. No CEL. Got it home and hooked it up to $eeHack - no codes. On a whim, hooked it up to Scan9495 for a second opinion since $eeHack can be buggy on b-body wagons. What do you know, it popped the code for "injector circuit". Put the stethoscope to each injector and found one that wasn't clicking. Voltmeter showed it to be shorted. Swapped out all the injectors for new ones and put back in the BKR7E's (two steps colder). Car runs like a top now, but its outside the 'circle of trust'. I'll update as time goes on.

The bad injector ohmed out perfectly once it had cooled off, so that explains why I was unable to track it earlier. I was waiting for the engine to cool before digging in.

Knock counts are still increasing - no change from prior plugs.

As stated in other threads, the gears (3.42) are sitting in a box in the garage. Have not had the expendable cash to install them. Plus, I'm leaning towards getting a new carrier versus installing new gear on the old carrier - so the bill will go up substantially. Given the looks of the colder plugs though, they show signs of lugging the engine so I may bump up the install date to sooner rather than later.

The stall is fine, perfect actually, for what I want, and was chosen based on input from the manufacturer as well as Karl Ellwein and Lloyd Elliot. Its a Yank. Around town, it drives so close to stock, that I literally could not tell it was in there when I first installed it. Romping on it is a different story.

Once I get the gears in, the stall will be perfect for what I set out to accomplish. Your mileage may vary.