Z-RATED94

iTrader: (6)

Nitrous rookie here wondering about jetting and the weather. Should I be changing the fuel jet on my plate kit if the DA is off quite a bit from where the car was dyno'd at? On the dyno it was 11.3, which I take it is a little leaner under full load, correct?
The other day at the track, with the DA around 3000 the car backfired and bent the TB blades. I know I should learn to read plugs and will soon start, but for now should I adjust the fuel jet for the DA at hand?
I'm using a 62N + 41F. Would a 39 or 40F be more appropriate if it's a bad air day? Thanks for any help or advice you might have.

5_02ls1

iTrader: (20)

11.3 is way to rich...get a wideband in the car and learn to read plugs.....

ShiznityZ28

iTrader: (11)

Way to rich. You want to be around 12.5 (verify with the plug) .its a good starting point. how much timming total and retard?

your fuel jet should be like 32-34. As it gets hot out the kit will get richer you probably were in the 10.5 range.

Z-RATED94

iTrader: (6)

Thanks for the fast reply guys. I have my eye on the LM-1 for a wideband. As far as the A/F, I was told it might be more like 11.6 under full load compared to dyno's 11.3, what's your take?
Initial timing on my LT1 is 33 and I'm pulling 5 degrees with a Mallory 685 box. I'm also using the TR6s which I will also change out to the 7s in the near future.

Z-RATED94

iTrader: (6)

My mistake guys. The 62N 41F was for the first pull on the dyno. It's the recommended starting point of 62N 38F right now.

SPEEDYws6

iTrader: (9)

If it bent the blades then they were either closed or close to closed and it shouldn't have been spraying...but like said above, that is fat.

Z-RATED94

iTrader: (6)

Good point. I have no idea how it happened. Maybe it farted once I let off at the finish line, who knows?

ShiznityZ28

iTrader: (11)

Most cars will be between 12.3 and 13.3 we start at 12.5 but id take 9 out of 33 to start. put the 34 fuel jet in and make an 1/8 mile pass. see if it picks up. pull a plug and see where the timming mark. keep it just on the tim for the beginning. lean it out until it slows down then go back. watching the timming mark.

buzz12586

iTrader: (17)

Just wondering if I have this right. The closer the timing mark is to the tip of the plug the colder the plug was during the run. As it moves towards the bend it means the plug was hotter during the run. Is this correct?

ATVracr

iTrader: (5)

Yes!.

buzz12586

iTrader: (17)

So in order to make it hotter or colder you adjust the timing but what about the fuel. I have heard about a "fuel ring" when people talk about reading plugs but not sure what they mean.

ATVracr

iTrader: (5)

Adding fuel will move the timing mark to the colder side, leaning it out will put more heat in.

The fuel ring is at the base of the plug where the porcelin meets the metal.(hard to see on most plugs)
Should look like you drew a line on it with a pencil.
A thick line is richer, no line is lean.


Here is a pic of my plug last year....

buzz12586

iTrader: (17)

So you would use the fuel ring to decide if you should add or remove fuel and then the timing mark to decide if you should add or remove timing?

ATVracr

iTrader: (5)

Yes but no big changes and try changin 1 thing at a time so you can see what it does to the plug and the timeslip.
If you change a bunch of stuff you wont know what did what and why.

buzz12586

iTrader: (17)

Sorry to hijack this thread. Thanks for all your help ATVracr.

Z-RATED94

iTrader: (6)

No hijacking that I can see, we're all trying to learn. ATV and Shiznity along with a few others seem to have a lot of knowledge that their always willing to share. I do appreciate it because I know that knowledge was through hard work and expence.
Shiznity, if I pull the 9 out of the 33 do I really need to change all the plugs to start over? Their a fresh set with two runs on them. Can I put two or 3 easy to reach ones in to take a reading? I'll have to stop on the return road as I'm a small dog with limited resources. Do you think I have a chance reading the fuel line with my 10x loop? I also have one that has a light built in. And last but not least, which are the problem cylinders on an LT1, I forget.
Thanks much to all for helping out. Rick

ShiznityZ28

iTrader: (11)

Yeah you can just put 2-3 in. if you find 1 that has the most timming use that cylander to tune off of until you get a handle on it. on a 7 or 8 its hard to see down the bottom but on a 10 or 11 its easyer. if you have a 10x you should be fine. you cna also use the barrel at the top to see fuel but you have to kill it and do not idle on it at all. we try to get 3/4 of a barrel of fuel at the top to start. where you end up depends on what the car wants. I ay take 9 out but you ill probably put 2 or so back in but when leaning it out you want to be safe on the timming and work up.

buzz12586

iTrader: (17)

Is it easier just to cut the end of the plug off?

V3NOM GTO

iTrader: (3)

I have just recently started reading plugs. I have a H/C with 16* total timing and according to the plug and fuel ring its perfect. A dyno reported it to be pretty rich but I dont have alot of faith in there wideband.

ShiznityZ28

iTrader: (11)

yes its easyer to see if you cut the end off. use a angle grinder and cutoff wheel .it will nt cut threw the porc so its pretty easy.