NOS kit owners in here!!!!
Configuration N F Configuration N F
75 41 26 175 67 47
100 51 31 200 73 51
125 55 35 225 78 55
150 63 44 250 83 59
These are the recommended jet sizes and all the ones I have ONLY UP TO A 150 SHOT. I am going to a track rental the 14th at Atco and I'm just curious to all the Nos user if they are working and what jets you guys are using for the bigger shots 175,200,225,250 ect. My car is a stock bottom end H/C/I car and I have the racetronix pump and hotwire kit. I am pulling off the rail no standalone. From reading in this section I understand the kits come jetted a bit rich. I would like to go up to a 200 shot I think the fuel pump can handle it, what do you guys have think? I have a fuel pressure gauge I will be watching like a hawk. So I was thinking of picking up 42,40,38, 67/46 for a 175 shot and a 73/50 for a 200 shot then a 48 if I have to lean out the fuel. What do guys think about these jet choices? I read in another post that 78/44 for a 200 shot was being used and that was rich do it turned out to a 35 fuel jet. I don't know what kit this was and I think it was out of a standalone because the fuel pressure was higher. Well what you guys say post up!!!!
I will most likely be ending up with a 74N and 38F for my 200 shot tune-up once I get the small bugs out and hit it on the 62N 38F just to confirm the tune-up is showing no heat on the strap and rich still.
I started with a 62N 38F at 58psi and it got me 11.8-11.9 afr with no heat showing on the plugs and more of a fuel ring than I would like to see. Hoping the 74N 38F combo leans it out a half a point and get's me into the 12.4-12.6 afr range. Also will be pulling 4 more degrees on top of the 8 total that is already pulled out for the 62N 38F and using 50/50 race gas pump gas mix for added safety.
Lean is mean. Don't be afraid to lean it out, BUT make sure the timing is pulled back more than you would think it needed to be. When your leaning your tune-up out you always want to take away as much timing as possible without making it go dead and then add it back in slowly a degree or half degree at a time until it's where it should be, but don't chase the timing mark looking for a better number.
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Changing jets, and making adjustments, without putting fresh plugs in so you can get accurate reads, again is a really good way to blow the motor up. 4 degrees pulled out would normally be a good start, but from what n/a timing are we talking about? Depending on where the n/a tune is you may, or may not need to pull more then that.
Changing jets, and making adjustments, without putting fresh plugs in so you can get accurate reads, again is a really good way to blow the motor up. 4 degrees pulled out would normally be a good start, but from what n/a timing are we talking about? Depending on where the n/a tune is you may, or may not need to pull more then that.
Reason being is when there is more fuel in the chamber to help cool the strap heat doesn't show as much on the strap and thus can hide the true timing mark.
When you begin to lean it out, more heat is shown on the strap and the timing mark can and most likely will make a move towards the bend of the strap when this happens if the timing is left the same as it was on the richer fuel jet.
This is why it is very important to be conservative with the timing and pulling more timing even when your not going up in nitrous jet size as the heat from leaning it out will move that timing mark closer to the bend or past it.
Reading the plug is the only way you can see this for yourself.
I learned this with my turbo car. I kept trying to figure out why as I leaned it out more and more and keeping the timing the same that the timing mark kept moving further and further towards the bend. I had heard that this timing "number" I was running was acceptable, but again you have to read the plugs to truly see what your changes are doing and not going on blind faith.
Good luck.






