Xavier8

Just finished installing a NOS top shot kit on my holley 465 equipped 12a. I drove it today with a 50 shot, and immediately have problems. I know both solenoids are working fine, fuel pressure from holley blue at 6 psi, nitrous at 900, rpm switch turns on at 4500.
Runs great in 2nd, no noticable problems at all.
Surges and runs funny in 3rd, once ran to near redline with only mild surging
Doesn't like 4th, started to run stong, then went funny after 1second or so
I have no idea what this could be, with ideas ranging from needing a colder plug, pulling back timing, richening up the fuel side of the shot, inadequate fuel flow to the fuel solenoid. I just know there is a answer out there since the symptoms are created in higher gears under a greater load.
I have so far done maybe 20-30 seconds of spray total, as I do not want a lean condition to fry the motor. Glad I am only running a 50 shot right now till I get it right. Please give ideas and solutions, not unhelpfull comments about your dislike of nitrous.
One more observation, none of the funny stuff created a lean or rich load pop like I have gotten from other conditions.

Fatman0203

Made think about a wideband to see if your possibly running to rich or to lean.

deeman111

I say get it on a dyno and shove a wideband in it... with something like that i would definately get it dyno tuned
-James

Xavier8

I have pretty much figured out what the problem was- carb getting spray through the boosters, richening the mixture too much, and have since pretty much solved it. Still testing. I know I am not running lean so I am not too worried, also I am only trying to shove in an extra 50 hp, which is a pretty small shot of nitrous. I will eventually get it dyno tuned, but for now I am still tweaking.

Fatman0203

Well if you havent blown the motor I was guessing you were running to rich, wouldnt it be better though just to go to a dyno and tune it? I mean carbs are pretty darn simple to adjust. How high does that kit go? Remember something like a 50 shot drops to 40 hp or so do to drop in pressure. Thats why they have those bottle heaters and stuff.

Xavier8

its not the carb that needs to be adjusted, its the actual spray into the carb. if it goes through the boosters, it increases flow through them, and then they provide even more gas over what the wet shot is providing. I am working on adjusting the shot so it goes directly into the venturies and not through the booster. It is too bad my damn venturies are so small on that 465.
I have the bottle in the trunk where it gets pretty warm. Boost pressure according to the guage has been anywhere from 900-1100, even on cold nights.
After I am sure the spray is going into the venturies I will get it dyno tuned. Jets are not exactly cheap though.

Fatman0203

Thats another thing maybe you need to change the jets =/

Hans

I've heard you need to look out for the venturies icing up on long spray runs because of the pressure drop and cold nitrous.

If it were me, I'd drill out the nitrous jet a little bit, cheaper than tuning your carb and the increase flow wil make it a little on the rich side anyways

or better yet if you can mount the nozzles in the intake manifold, then you wont have to bother tuning your carb to work on or off spray only.

any whose, also every carb kit usually recommends 9-10psi fuel side, to be on the safe side in casue of drops in pressure(accel surge ect) may cause a lean condition.

hope this helps

Xavier8

I have no problem with fuel, the holley pump keeps up very well. I will remember about the ventury icing, I had not even thought of that.
I am considering just going to nozzles in the intake manifold, but that will be another 200 or bucks or so, so that will have to wait.
I am running way too rich, and I know it, so I'll buy some jets and head over to the dyno. I am tired of it running wrong. When it hits right, its fast, but too rich.

12abridgeport

Hey man, i had nothing but problems with my 50-100 shot on a '91 n/a with holley 600 and holley fuel pump. Hope you can solve yours...i just turbocharged mine...but it never worked anyways...screw it...no replacement for deplacement

Xavier8

Well, update, I am now a card carrying member of the good working nitrous club. A 50 shot of the top shot system is suppossed to use a 37 nitrous/42 fuel jet, but this led to an overrich mixture, especially at very high rpm (7-8k). I bought some jets today and replaced the fuel jet with a 40. This has solved 95% of my problems. Car pulls very very hard in 1st, second, and third, which is enough for 90+ mph. Still slightly overrich at around 7600 or so, but much stronger in general all across the board. I also just did my testing in 90+ deg heat, so we shall see how it runs tonight with alittle cooler and denser air. Need to get the bottle filled before I take it to the dyno and find some more power. Excellent!

Judge Ito

check your over all timing advance. Especially when you get into higher n20 hp numbers. you want to see leading and trailing at no more then 20 BTDC for lead and 10 BTDC for traling. As you increase into a 100 hp shot and higher bring down your timing 2-3 degrees at every 25hp increase. Plus use atleast 100 to 112 octane fuel.. good luck with your nitrous mission. I'm still on my mission..