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Author Topic: Nitro Tune Ups  (Read 92074 times)

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Offline Virgil

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« on: December 08, 2005, 12:24:39 pm »
I have been asked many times for help in selecting equipment and for tuning tips for nitro classic funny cars.  I have no problems with passing along my opinions, but I am only one person and there are many ways to get the job done.

Frank Oglesby has previously posted a tune up he used on his car and over on Nitroland David Pace and Larry Fullerton Jr are passing along some information for tune ups.  These are good starting points.  Just remember to take into account the condition and size of your supercharger, just about all heads will perform better today, and the cam lobe centerlines.  

Your nozzles will probably vary depending on your blower (and it's set back), manifold and heads, but the total area should stay about the same.  And also consider that drop in jets flow about 15% more than enderle screw in jets.

Online David Pace

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« Reply #1 on: December 08, 2005, 01:40:32 pm »
Thanks Virgil.  I'd like to see a "one-stop" tuneup thread where everybody can post this type info in one location.  It would be interesting and maybe helpful to compare some of the different approaches.  I thought about posting this in the tech forum, but most of the traffic seems to be here, so I guess this is as good a place as any to start.  Here's the base tuneup we used on the Carroll Brothers' TF car in the early 80s, as I posted on Nitroland.  We ran 5.70/250 with it.

482 inch K.B.

Stage III solid cast aluminum heads (stock 426 hemi dimensions)

.150 out 3-8
.100-.120 out 1-2

Crane flat tappet, 105 centers

Bowers 8:71 42-48% over

Enderle Bug

Enderle 990 at 14% over (14.9 gpm)

Supermag III usually 69-72 degrees, but up to 77

94-98%

Idle check 6#

Hat
1 .101 2 .101
3 .097 4 .098
5 .085 6 .088
7 .030 8 .035

Port
1 .095 2 .095
3 .092 4 .093
5 .088 6 .092
7 .082 8 .082

Manual high speed .040 - .050

11" three disk, 6 finger aluminum Crowerglide
Finger radius varied from .125 to .218
6 1"L X 5/16" bolts, 6 full nuts (baseline)
1/2 to 1 turn stall
Anywhere from .035 to .060 pack clearance

1.31 or 1.44 Lenco

3.90 or 4.10 rear gear

1824/1777 tires

Bear in mind that this was in a rear engine top fuel car, not a funny car, but it was an NHRA top ten car and runner upped at Indy & Denver in '81 and grabbed the 11th spot in the NHRA 250 mph club, so it was fairly competitive for that era.

One observation on pumps...we had two 990s and three new 1100 Enderles and Emery flowed them for us on his bench at Beadle's.  The 1100 pump that we used without any overdrive in 2005 on the NTF car flowed exactly the same (17.9) as the best of those three new pumps did at 14% over, so I guess the pumps have improved some over the years.  Also, today's 6:71 blowers might be at least as good as the old 8:71s, maybe better.

We had several sets of the cast aluminum heads, some solid and some with water jackets.  Occasionally, when we were having trouble with dropped holes on just one bank, we'd put a water head (we ran water in the block) on that side and leave a solid head on the other, and it seemed to clean up the fat side so that it would run.  Seemed to be an effective quick fix without having to chase the nozzles around all day.

Would appreciate it if some of you engine/nitro gurus would post your tuneup info and/or tips for comparison.

David
« Last Edit: February 04, 2012, 08:23:14 pm by David Pace »
D. Pace

Offline Danny Miller

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« Reply #2 on: December 08, 2005, 02:36:10 pm »
Virgil & David,
I have never run a system with hat nozzles and both high and low port nozzles.  Additionally my pump was much smaller and the blower was not striped back then.  Therefore I am now using a Emery flowed 20 gal @4000 rpm pump, SSI stripped blower 18.8% over, 1.675 compression distance, 454 cu in solid block & heads and need a ballpark total jet area or jet sizes for hat, port (idle) and port (under power) nozzles.  What do these new blowers need to lube the rotors 30% of volume?  It has the 4 ports in the back of the blower 10" opening and retro bottom 60 degree opening at front.  I need a starting point.  Thanks for your suggestions.
Danny
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Offline Frank Jonkman

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« Reply #3 on: December 08, 2005, 02:37:24 pm »
Here is something that I found useful, it came from a good reliable friend.

-CLUTCH Three disc Crowerglide
6-finger hat, 1" bolt (on each finger), one full nut on each finger.
Stall (speed) think of a bottle of beer
.040" clutch pack clearance.
-TRANSMISSION
High gear only or 25% (underdrive) Lenco 2-speed.
-REAR
Final drive ratio between 3.60 and 4.10:1.
-BLOWER
GMC 6- or 8-71 with 20 - 30% overdrive (preferably not too fresh).
-FUEL PUMP
Fresh Hilborn - 4 or Enderle 1100 pump driven "straight up" or overdriven up to 10%.
-MAGNETO
Mallory Supermag III set between 50 - 60% BTDC (426 only).
-PLUGS
Spark PlugsAutolite 50 or equivalent gapped at .028".
-CAMSHAFT
Split overlap with .028" valve lash.
-BARREL VALVE
Set for 90 - 94% leakdown.
-MAIN JET
Blanked off.
-CHECK VALVES
Idle check valve at 7 psi, port check valve at 10 psi.
-INJECTOR
Two .100" air bleeds in rear, butterflies gapped to achieve idle at 2900  - 3000 on gas squirt bottle (2500 rpm on fuel).
-NOZZLES
Hat Nozzles    
# 1  -  .085"      # 2  -  .085"    
# 3  -  .080"      # 4  -  .080"    
# 5  -  .075"      # 6  -  .075"    
# 7  -  .070"      # 8  -  .070"    
Port Nozzles    
# 1  -  .085"      # 2  -  .085"    
# 3  -  .080"      # 4  -  .080"    
# 5  -  .075"      # 6  -  .080"    
# 7  -  .070"      # 8  -  .070"

Generally this tune up is very conservative, it will however allow any idiot to run fuel.  Just ask........
I once had a thought....

Offline dragcars

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« Reply #4 on: December 08, 2005, 04:39:02 pm »
now this is some of the stuff i was hoping to get from this site. (cuz i'm one of those idiots)
frank
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Offline Virgil

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« Reply #5 on: December 08, 2005, 05:23:40 pm »
Danny - decide your total area of all nozzles, then decide what part of that area is going to be for idle.  You can figure the area of the tune ups given by using the pie times radius squared method (I use Don Jackson's chart, much simpler) of each nozzle and adding them together.  Split the idle circuit to suit your tastes.

The reason for idle down nozzles is to balance the motor at idle, as blower speed changes mess with the distribution of fuel to each cylinder.  I run 10 staggered nozzles from .055 in front to .045 in the back above the blower.  I run the rest of my idle circuit in the manifold.  My run nozzles have check balls and springs set at 27 lbs to insure that they will not leak (open) while at idle.

Some tips:
The more fuel you run through the blower, the better it seals, the more boost that it makes, and the longer it lasts.  
The more fuel you run below the blower the better the distribution and your motor will run smoother.
Frank describes a good way to set the metering valve prior to start up, and then I make the final adjustments on the high side with a guage on the idle distribution block.  More idle pressure creates a snappier response at the hit of the throttle (better reaction times and 60 foots).  Start out somewhere around 2 - 3 pounds and adjust from there.  If you cannot get pressure, maybe the area of your idle nozzles is too big.  Take away from the down nozzles, not the hat.  If the pressure is too high, maybe your area is too small.  Experiment in small steps to get the best results with your combination of parts.

Offline Danny Miller

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« Reply #6 on: December 08, 2005, 06:45:29 pm »
Virgil,
How do you determine the total area you will use?  
The pump flows 6.5 gal @ 89 lbs @ 2660 RPM and 17.45 @ 100 lbs. @ 7000.  I assume you try to maintain a certain pressure at idle and use as much fuel as you can at that pressure but what formula  do you use to determine pressure drop / area increase?  Lets say I want 20 lbs at 2660 what area will give me that pressure and then at 8000 RPM I want what  pressure applying the same area to pressure formula.
Thanks Danny
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Offline Dale R. Thierer

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« Reply #7 on: December 08, 2005, 10:52:54 pm »
Everyone talks about finger radius on crower glides.We run a 11 inch alu.crower glide in the hemi hunter,when i talked to crower they told me they only have 1 finger.Any help!

Offline KDavidson

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« Reply #8 on: December 08, 2005, 11:59:20 pm »
Dale,
Dale Pulde gave an excellent explanation of the finger radius. If you don't have a link to his site, its.

http://208.255.199.109/forum/

I do miss his posts.

Stuff like this is what this site needs. So us that want to go nitro have some sort of assistance.
IMHO the best site for alky on the net is insidetopalcohol.com.

Info on there that will make you think....

Online David Pace

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« Reply #9 on: December 09, 2005, 07:30:16 am »
Quote (Dale R. Thierer @ Dec. 08 2005,21:52)
Everyone talks about finger radius on crower glides.We run a 11 inch alu.crower glide in the hemi hunter,when i talked to crower they told me they only have 1 finger.Any help!

Dale, we used to build them up with weld and then form grind the radius on a surface grinder.  We built a fixture to run a whole set at one time.  These days I just make my own, either on a CNC mill or a wire EDM.  I was told to use 4130.  That's what I've been using, and they seem to hold up real well.  You can also move the pivot hole around to make 'em behave (or misbehave) a little differently.  Like anything else, you can go overboard with it if you're not careful--.005" can make a difference.
D. Pace

Offline Virgil

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« Reply #10 on: December 09, 2005, 11:18:21 am »
Danny - the choice is yours.  Here are some givens:
Enderle told me to start with an area equal to sixteen .070 nozzles which equals .0615744 area or .280 hole
Fullerton's area is .0623887 equaling .282 hole, idle area .0264426
Oglesby's area is .0800856 equaling .320 hole, idle area .0369342
Jonkman's area is .0758692 equaling .311 hole, idle area .0379346
Pace's area is .0952906 equaling .348 hole, idle area .044382

I run 10 nozzles in the top of my blower going .055, .050, .050, .045 and .045 down each side, for a total area of .0189672.  Subtract that from the above areas and divide by 8, and the port idle nozzles would start out as:
Fullerton's - .035 equaling .25 gpm @ 100 psi each
Oglesby's  - four .053 and four .054, equaling .6 gpm @ 100 psi each
Jonkman's - .055 equaling .64 gpm @ 100 psi each
Pace's      - .063 equaling .8 gpm @ 100 psi each

This gives you four starting points with variations on each.  They will allow you to start the car and it should run.  None of them are going to be perfect for your equipment, so do not be afraid of making changes based upon what your car is telling you.

Offline Danny Miller

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« Reply #11 on: December 09, 2005, 12:00:12 pm »
Virgil,
Thanks for the insight.  I have a starting point now.  See you this summer.
Danny
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Offline rex

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« Reply #12 on: December 09, 2005, 12:25:34 pm »
virgil, Can we use down nozzles as run nozzles or are they saying we have to have two sets of ports??
                              rex

Offline Virgil

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« Reply #13 on: December 09, 2005, 12:55:32 pm »
Rex - run what you want.  I believe the VRA mandates a maximum of 24 nozzles, with 8 on top and 16 in the manifold.  But you aren't planning to run VRA so it really doesn't matter for you.

Offline dbn55

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« Reply #14 on: December 09, 2005, 10:39:37 pm »
Now is this not the best. I remember when I bought my car 4 years ago, and was told that the minimum cost to get this thing down the track would be around 50k. It is the best thing that there are guys who will share this stuff. And it makes sense as the more the better for all of us. Man can u imagine trying to get a degree in the black science?'<img'> It's like goin to school for 40 years @ 4000.00 per year and then payin for the parts, the fuel, the oil, H.F. yer lookin @ HUGE Jack. All this info is really helpfull to all. Thanks to those in the know. It's funny guy's call me and ask what the deal is, and I tell em that why u aksin some dumb @ss like me?? the only thing that I know is like old Don Sosenka told me check it 3 times and don't try to piss it off. And u'll be O.K.  ':cool:'

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« Reply #14 on: December 09, 2005, 10:39:37 pm »
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