nonnieselman

iTrader: (10)

im not an expert on gap sizes but what does it matter? I know if you go to large of a gap then it is possible that the piston can hit the plug and either crack the piston or close the gap on the plug (seen it happen alot with my brothers 250R), but i could understand that with a slighty smaller gap that the flame couldnt be blown out as easly??
just curious for an explanation.

Mort

That was for all engine options for the '03 Silverados including 4.3L code W, 4.8L code V, 5.3L code T, 6.0L code U, 6.0L code N and 8.1L code G. The factory specified plug gap is 0.060" for all '03 Silverados.

callie

I thought the .060 gap was only for factory type iridum (sp) plugs. Also seems like if you go with a .040 gap opposed to a .060 gap gas milage will suffer. Does anyone know for sure on the gas milage issue? I haven't put enough miles on the truck so far to tell. But in stock form it was only getting around 12 in town which is 95% of my driving. I was pleasently suprised when I put the w4m tune in it went up to 15.5 and was not a gas mileage tune. But I can say the w4m tune made it a different truck altogether, much better driveability and superb performance. I did go with a ***** out tune at least that what I requested and it seems to be just that. So maybe someone can comment on the difference of gas milage factors with a .040 gap opposed to .060 gap plug. Thanks!

Mort

According to the NGK site the gap for a TR55GP G Power Platinum Plug for a 2005 Chevrolet Silverado 1500 / V8 / 5.3 Vin Code T is 0.060". This is the gap they specify for all plugs that they recommend for your truck including Laser and Iridium IX.

This is what NGK says about plug gapping:

3. Gapping

Since the gap size has a direct affect on the spark plug's tip temperature and on the voltage necessary to ionize (light) the air/fuel mixture, careful attention is required. While it is a popular misconception that plugs are pre-gapped from the factory, the fact remains that the gap must be adjusted for the vehicle that the spark plug is intended for. Those with modified engines must remember that a modified engine with higher compression or forced induction will typically require a smaller gap settings (to ensure ignitability in these denser air/fuel mixtures). As a rule, the more power you are making, the smaller the gap you will need.

A spark plug's voltage requirement is directly proportionate to the gap size. The larger the gap, the more voltage is needed to bridge the gap. Most experienced tuners know that opening gaps up to present a larger spark to the air/fuel mixture maximizes burn efficiency. It is for this reason that most racers add high power ignition systems. The added power allows them to open the gap yet still provide a strong spark.

With this mind, many think the larger the gap the better. In fact, some aftermarket ignition systems boast that their systems can tolerate gaps that are extreme. Be wary of such claims. In most cases, the largest gap you can run may still be smaller than you think.



With your application I would probably stick with the stock gap of 0.060". Is there a reason you are installing new plugs? Your stock plugs are good for 100K AFAIK and there is no advantage to installing new plugs. The plugs in your engine are probably NGK Laser to begin with.

callie

Thanks for the information on the gap from NGK! I installed the tr55 plugs to try and get rid of a small amount of spark ping after the tune was installed. I had read that the tr55 sometimes will help a small amount for pinging. I am guessing now that it is the .040 gap instead of the tr55 plugs that help. I could have just regapped the factory plugs. That is all hindsight now.I haven't had a chance to test the pinging problem yet, weather is not cooperating. How will going from a .040 gap to .060 affect pinging? Will the bigger gap make the pinging problem better or worse? Thanks!

Mort

I am not exactly sure how the gap will affect your pinging issue. If your coils are strong enough to bridge the larger 0.060" gap then you should get a better flame front and more complete combustion and better power. Your coils are made to handle the 0.060" gap and that should not be an issue.
If you are experiencing pinging with a new tune then you should contact the tuner. The pinging will be related to timing and/or fuel and your tuner will need to adjust for it if your mechanical systems are in good shape and you are burning good quality fuel. The other thing to try is a top end cleaner to clean out your intake manifold and combustion chambers. Sea Foam seems to be a popular product but I have never used it so I have no personal experience with it.
I don't think I would use plugs to correct for a pinging issue unless they are known or expected to be bad, have high mileage or are visibly worn. If your mechanical systems are all in good shape then I would contact your tuner and discuss the problem with them.
The owner's manual says a little pinging noise when you accelerate or drive uphill is considered normal.

callie

Thanks, I will be calling the tuner tommorrow to send the PCM back for tweaking. Thanks for all the help and information from everyone!