ahittz24

ok, so last night I wrapped up the zex dry kit install with a 75 shot and took it for a drive.

mods are as listed:

GT40 heads
Comp Cams 281HR Cam
Cobra Intake
.030 Overbore Stock Spec bottom end
Pro Form Roller Rockers (1.6)
24lb injectors
BBK Adj Fuel Pressure Reg set at 50psi
Timing is at 12 degrees
BBK Shorty Headers Equal Length

I got on the gas (WOT) from a stop and immediatly heard popping in the chambers and exhaust when the Nitrous began to enter the engine. So I cut it off and just drove normal to make sure I didnt mess anything up. I drove for a couple mins and everything was fine (no overheating, no white smoke) and decided to try it again with higher RPM's. I got the engine to 4k in 2nd and again gave it WOT and it worked fine at Higher RPM's but when i shifted to third, it popped once more and I decided that I need to stop before I broke something and ask some questions.

I read in the zex manual that for a 75 shot it says Ignition Retard is 0 and for a 100 shot Ignition Retard is 2 degrees and for a 125 shot Ignition Retard is 4 degrees. So my question is, does this mean I should set my timing at 0 with the spout pulled, or does it mean to retard timing 0 from base timing (10 degrees)?

Also with the mods listed, will i need a Fuel pump upgrade, I have a carter pump that supposedly flows 25% more than stock, whatever the stock pump is.

Should I set the fuel pressure higher on the regulator?

I dont want to mess this engine up, I just finished the rebuild and it would not be a good thing to blow it up.

AdderMk2

bring your timing down to 10°, you may have to run 8, you should have gone with a wet kit, and you should stop spraying until you get a tune

ahittz24

ok, I am ordering a Tweecer RT now (I know you hate those Adder), and I will have it Tuned ASAP.

I was thinking about ditching the Dry kit and going with a Compucar wet kit (they are local in my area). But what about the Fuel Pump? should what I have be fine for the mods listed or should I look into a 190lph or a 255 lph?

AdderMk2

your spraying on a stock pump...


go clamp your nuts in a vice, moron..

we will wait...

ahittz24

nice.....

I will also look into a better pump

capri debris

If you're not using a window switch that only lets it spray between say 3 and 6000 rpms, then you don't want to go WOT until you are turning at least 3000 rpms. Get a bigger fuel pump and adjustable regulator, then look into a dual tune... one for just the engine and one for the spray. Never over rev and float the valves or you'll blow the upper intake through your hood. The tuner will set your fuel pressure and timing where it needs to be. Hope this helps. And as said before, you should've gone with a wet kit... dry can be used or they wouldn't sell them, but I think they are just too risky.

PJC Racing

Safe initial tune for NO2: retard 2 deg for every 50hp of NO2. For 75, you should start by retarding 3 deg then read the plugs (after upgrading the fuel system).

Ohh, and you did upgrade the valve springs to work with that cam, right?!

ahittz24

Yes I did, they are comp cams springs with matched/set spring rates.

I am looking at 255lph fuel pumps right now, i am looking at the Walbro and Holley pumps, are they both good? any bad experiences with these?

Portmaster

Walbro all the way.

FivePointOhh

agreed! every since i swapped mine out i dont have that ridiculous *whaaaaaaaaaaaaaaa* noise the stockers do. i cant even hear the FP kick on unless im back by the tank listening for it.