nitro

[ivan]

I am building a old school altered I am going to run smallblk chevy on alky via tunnelram and birdcatcher also wanting to run some nitro for fun thinking around 50% at least ,question is barrel valve ,pump , compression .can I run straight alky, then do the nitro with same pump and barrel valve, realize ofcourse have to change nozzles, just want to play with this stuff a little. also any help on tune up on both combo's appreciated , nozzle size , timing etc. thanks

[Jeff Smith]

I'd start off talking to Enderle. They'll let you know what ramp and nozzels to run for straight alky as well as what percentage of nitro you can get away with before you need to start making changes.
I'm setting my dragster up with a 355 with a flying toilet and Rons told me to start with .032 nozzels for 600+ horsepower on alky, and I can add up to 25% nitro with the ramp I have.
Enderle will set you up on the rich side so plan on buying a set of nozzels 1 or 2 sizes smaller than what they reccomend. When you start running heavier nitro loads you can switch back to the bigger nozzels. Just remember to start where they tell you and go leaner from there.... a little at a time. Have fun!!
Jeff

[slickvic]

what u need to do is have your system flowed , so you know what the pump flows at what rpm and with what nozzles.
if you go to larger nozzles your pump pressure will drop.
if you go with smaller nozzles the pressure will be up.
the key is to know what pump pressure is with a given nozzle size at what rpm you need pressure for atomization.
ive run nitro, but currently i am running a rons toilet also.
hope this helped.
OH AND P.S...if you start putting nitro to it you are going to need to boost up your ignition system also.
VIC

[nitronurse1]

question for jsmith, is that 355 a factory block or aftermarket?whats the max % nitro you would gamble with, can you tune the pipes with rons?

[Jeff Smith]

The block I'm using is an older 2 bolt stock chevy block, filled with 4 bolt splayed caps. It should hold up to 800 ponies with no problem. As far as tuning.. I'm used to tuning a blown alky rat motor in NE1 and CIFCA, the Rons is new to me so I'll be calling Rons when I have questions. They reccomend .032 nozzels with a "0" pump for 500 hp with a barrel valve leakdown of 20% as a baseline for the system I have. I'll work my way up from there. With any luck I won't need to add nitro. I havn't decided on headers yet. I'm building a set of 1 1/2 id zoomies and I have a set of 1 3/4 brodix collector headers to experiment with. I plan on running NE2 because I don't really want to push my 40 year old chassis any harder than 8.60, and I'm not gonna run my motor (and stock crank) on the ragged edge of what it can handle.
The zoomies look and sound way cooler on a nostalgia digger so I'm hoping I don't need the collectors for the extra push on the bottom. The whole purpose behind zoomies is no back pressure. In my opinion, if the zoomie tube is bigger than the exhaust runner you out flow the head so there is no tuning. a collector is a diffrent story because it creates vaccume and helps suck the gasses out and collectors are tunable by the length of the collector. I'm sure there are other opinions out there and I hope to hear some of them. I d**n sure don't know everything.

[nitronurse]

more questions from the nitronurse : what kind of bearing clearances on rods and mains on alky motor, short or long rods?does it always have to be high compression? will mallory mag 3 be o.k? thanx in advance for all the help!

[Jeff Smith]

I'm running .0035 clearance on 6 inch rods and yes!!Alky loves compression!! The mag should be fine.. we run a mallory sprintmag 2 on the blown 482 chevy with 11.5/1 compresion and it works just fine. I really don't notice much diffrence in tune-ups from the vertex w/external coil. We vaporize between 1 1/2 to 2 gallons a run. It all depends on how much fuel it takes you to do what you want to do. I know some racers who just run a vertex with the internal coil on blown motors and can dip into the 6's.

[nitronurse]

just when you thought the questions were over ! on alky what timing should i start with ? at what point does it change when you up the nitro % ? do you read the plugs the same as gas? do i need a roller cam? overlap, lift, duration starting point with small block ? does the motor have trouble building heat?

[Jeff Smith]

It all depends on what class you plan on running. If you're running NE3 you dont need too much to run the number. If you're running A Fuel.. you'll need a big roller cam and very large bag of money. As far as plugs go.. with alky you want to see heat down to the 1st or 2nd thread.. any more than that and you done broke it.