Found this somewhere on the net. if anyone wants to read

I know the NOS suggested jetting is larger on the fuel and that will be dead rich. Will it run? Sure. Will it hurt anything? Likely not at these low HP levels. Are you getting near what you should from the kit? Absolutely not. It has been preached for years that "rich is safe" and most guys tend to believe it, but that could not be farther from the truth. Excess fuel just beats the crap out of the rings. 99% percent of nitrous related engines failures are from too much fuel, too much timing, or both. It is EXTREMELY rare to burn a motor by getting the nitrous system too lean. Barring a mechanical malfunction or an extremely bonehead tune up change, that is nearly impossible to do.
Fuel color on the end of the plug, on the flat face, the last couple threads, or whatever, has nothing to do with the tune up. That is from idling, driving it back, or something similar. The mixture is read at the very base of the porcelain and if you can see a ring of color with your naked eye, you are DEAD RICH. The base of the porcelain should be a clean white and if there is color there, it should take a magnifying plug light to see it and it should be very faint. At this point, you will be somewhat close. Dark specs is usually detonation and the fact that you described your straps as a "grey color" sounds to me like you have too much lead in the motor. If the strap or end of the plug looks like it has been hot, such as this "grey color" you describe, it is generally over timed. If the gaps open after a run or the sharp edges are no longer sharp, you are over timed. Depending on the plug you run, there will be no "heat line" on the strap. If you run NGKs (and you should) and see a "heat line", you are over timed. The proper tune will deliver a plug that is scary clean on the porcelain and a strap that takes on a little of a dusty cinnamon color on the strap....
You did not ask, but one other thing, the weather does NOT change your tune up. Does not matter if it is 30 or 130 outside, it is always cold in that intake. Once you have the mixture right, the only thing you have to change for good or bad air is the timing. And "rich" is not safe. You have to do something horribly stupid to get a motor lean enough to burn it. You will slow the car down before you get it lean enough to burn a piston. An overly rich tune, on the other hand will beat pistons out of the motor in short order. 90% of "burned pistons" are caused by a rich tune.

Good read. Not knowing anything about nitrous (other than not to call it nos), It makes sense .

I disagree on the weather changing the tune to some extent, watergrains play a role..... plus if you are right on the edge in so so air and you get some mineshaft conditions and make a hit you might hurt some stuff lol.

Timing is a big deal.....

richter69 wrote:I disagree on the weather changing the tune to some extent, watergrains play a role..... plus if you are right on the edge in so so air and you get some mineshaft conditions and make a hit you might hurt some stuff lol.

Timing is a big deal.....

again, X2. BS the weather doesn't change the tune up. Watergrains play a HUGE role. I've been on the edge in perfect conditions. It got cooler out that night, we put more fuel in it and didn't touch the timing......booooom.

I would have to disagree as well with some of the info post as well. This is one of the thing I do not like about the net these days. Not everything is correct and gets spread around as if it's the gospell.. There are things that are close and things that are not in my opinion. Nitrous is one of those things that has the domino effect. Meaning in most cases how you do one thing will effect the next thing down the line..

1. First, I would agree that the old tunes do leave a lot on the table. we prove this to customers ever day when we flow there systems and they go out with less nitrous jet and WAY less fuel jet then there previous tunes and go as faster and in mant cases faster. Do the old tunes hurt parts, not in many cases if other things are correct. Remember, the big companies have sold thousands and thousands of kits jetted this way over the last 35+ years and not every user hurt things. I'm not saying it was right, just saying what was done over the years. We still see guys running "old school" jetting and hauling ass without hurting parts. Does't mean we can't pick them up still, just sharing both sides of the coin from someone who see's it every day..

2. As far as burning an engine up from being to lean. It happens way more commonly then you might think. There is a difference from a little lean and a lot lean as well. Timing plays a BIG part in what you will get away with in a lean condition. But in many cases if a guy doesn't know he's over lean, he won't know he's over TIMED either. It's easy to say you can't hurt one lean, if you ALSO use the disclaimer that you better be way under timed too..

3. On a plug I commonly tell our customers THERE'S NO ONE PERFECT LOOK to a spark plug !!! There are many things that will determine what YOUR plugs need to look like to keep YOUR combo happy. I have also found that having the poroclain naked white is not always ideal for best power. Remember fuel is ultimately what make HP !! But again, having the combo timed properly is keep to power as well. I myself like to see a LIGHT smokey gray ring at the bottom of the porcelain. One you have to look pretty hard to see with the naked eye. I have seen naked plugs be slower then lightly colored plugs in many cases. Plus it takes away some cushion of tuning as well for many..

4. On the timing marks. Again, there's NOT one set place it needs to be to be best for your combo. Different combo's need a different look and the more efficient and engine is and or the more nitrous and fuel your putting into and engine the less of a timing mark many will need to have. I can't tell you how many of our customers have called and said" my plug looks great, timing marks right ON the bend". I'll then tell them, lets RETARD the timing one more degree and see what happens ?? Next thing you know they call back and say... Shit it picked up 1 MPH. LOL TIMING will make or break a tune more then anything else..

5. Also another commonly INCORRECT quote I see is timing will not effect the look of the fuel on the plug. NOT TRUE. Timing is one of the key factors in how hot a plug gets during a run. HEAT is what needs to be made to clean the porcelain during the run. If you retard the timing far enough to cool the plug, it WILL look richer then when timed properly. DO NOT mistake this for run your combo rich and over time the hell out of it to burn the fuel though !!! I base my timing numbers buy 35+ years of working with nitrous and thousands of hours of tech help gather the data from racers I have worked with. This being said, I commonly can tell when a combo is over or under timed based somewhat on the laws of average and years of experience too..

6. Weather is important to any engine running properly. The carb set up or program can somewhat play a part in this as well. I many cases from good weather to bad I do NOT touch the fuel pressure. Just watch timing. I many cases good to bad is determined by water or humidity in the air. This is the key again to the most important part of the tune up... TIMING !!! You CANNOT burn water. The higher the water/humidity the slaower the flame front and the more timing you can get away with. The dryer the air becomes the faster the flame front, so you will need to retard the timing. Just a little food for thought..

In closing, yes over fueled and over timed can both play a part in a destructive tune. I feel the key is a ballance of a good clean tune and proper timing. That's where the power and reliability is at.. Hope this helps.. Thanks, SJ

Bump for the good info. Lean+Nitrous=Not Good. Lean+Nitrous+Too much Timing=Bad Nos Systems, probably figured those first Cheater Plates where going on Street Cars with weak fuel systems, and left some cushion with the fat fuel jets. Alot of them where T'ed off a 5/16" or 3/8" line and stock fuel pumps. The old 73N 82Fuel worked very well for me for 150hp rated shot, with a Cheater Plate and 175hp with a Big Shot, supposedly. Some of the new recomended tunes I see are scarey, after using the old ones, for 25 years. I am not saying they won't work, and that they don't make a little more power with everthing perfect, but they seem to be on the hairy edge. If a carb is on the lean side, the timing a little high, fuel filter, a little dirty or restricted, ect. more fuel is the safer bet. Don't forget, some of the junky intakes, these plate's may have been bolted to, that would run one or two clyinders leaner than the rest. Think of a Generic Holley Carb., it is jetted close, to be used on many different engines, and the end user has to fine tune it for their combination.