If you recall, last month we covered some of the larger parts and pieces that go into an "outlaw" style fueler. Thankfully, the attendant has brought us a fresh box of crayons, and now we can get into the finer points of setting up our low buck projectile. We'll begin where we left off.

Buy the best mag you can afford and have it serviced on a regular basis. A good Mallory Supermag III lights all the fire a nostalgia fueler can generate.

One of the biggest differences between the 392 and 426 Hemi fuelers is the amount of ignition timing they can tolerate. The 426 is much more forgiving and seems to be happiest with the mag twisted to around 60 degrees. It's not unheard of to light the fire in a single mag 426 as much as 70 degrees BTDC, but hey, why tempt fate. The earlier motor, even when built around an aluminum block, is still more prone to bottom end destruction, and so keeping the timing way shy goes a long way towards keeping the thing together.

According to master tweaker Pete Jensen of Sterling Engine Service and "Foothill Flyer" fame, the early-style 392 motor is happiest with no more than 35 degrees in the mag. Pete also explained that there's a range of approximately 15 degrees (from 35 - 50 BTDC) where the 392 is just miserable. Once past that hump though, the motor seems to get "happy" again.

By the way, whenever you set the mag on a fuel motor, always do so while twisting its rotor as hard as you dare against the direction of rotation. Remember, when you hit the throttle, the motor jumps but the mag doesn't. Twisting the rotor insures the timing you dial in is the amount it sees when loaded.

Keep this in mind as we go through the tune-up. There are many methods and theories as to what the optimum fuel engine tune-up consists of, and what we'll outline here is not one of them. Rather, what we're giving you is a baseline set-up that will get your car down the track. By setting up "soft" you can make the laps, come to grips with the various causes and effects and begin to formulate your own foundation of knowledge.

Also, many variables must be taken into consideration when tuning a specific combination. What follows is a truly broad stroke in the name of accomodating both early and late-style motors in an average car. If you don't have anything really bizarre in your basic combination and haven't done anything real stupid, this should work for you.

One other thing. If the combination you're planning on is for tournament style legal competition, consult with the rule book of the club or organization you intend to run with. Some of the things we talk about may or may not be legal with everybody. This tune-up is really more for match racing than a blueprint for a competitive race car.

• Vehicle
  Front-engine dragster or altered weighing 1400 - 1800 lbs. wet and ready to run.



• Clutch
  Three disc Crowerglide; 6-finger hat; 1" bolt (on each finger); one full nut on each finger; stall (speed) set tight enough to achieve slight drag (200 - 300 rpm) on jackstands; .040" clutch pack clearance.



• Transmission
  High gear only or 25% (underdrive) Lenco 2-speed.



• Rear End
  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).



• Spark Plugs
  Autolite 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
  Proper stagger and jetting is only achieved through trial and error with any given combination of blower, intake manifold, cylinder head, etc. The following setup, however, puts each cylinder within .005" of optimum for engines between 400 - 450 cubic inches. (NOTE: These jet numbers are on the fat side for safety !)



• 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"



• Nitro
  This is the thing that freaks people out the most. Low percentage fuel engines cannot use the kind of volume that high percentage combinations can. This leads to a motor that's generally down on power and detonation prone. Don't be afraid to tip the can! The combination we outlined here works best with an 80  - 90% brew. If you attempt to run it on anything less than 80%, you'll have a fat, sloppy pig on your hands. Anything more than 90% and you're on your own, though we've used this basic tune-up with as much as 94% (hey, we were hung over) and the car was just lovin' it!

OK, so now you possess all the basic knowledge necessary to whip up your own blown and injected nightmare and commence Earth rotation, right? Wrong! See, here's the thing. There's no possible way to cram all the little tidbits of knowledge, wisdom and insight that go into the fine art of fuel tuning into the space of a short magazine story (or the entire magazine for that matter).

Fuel tuning is a somewhat intuitive process requiring years of hands-on experience as well as the ability to accurately process a thousand bits of information and abstract minutia. In this respect you're not ready to go until you've secured the supervision of an individual experienced with the hands on operation of a fuel car.

If the thing's spittin' fuel out of the pipes or poundin' rod bearings on the burnout, you need to have someone around who can decipher this sort of information and make the subtle adjustment(s) necessary to bring it around without straying too far from the baseline.

Most importantly, take your time, talk to as many people as possible, treat all of your equipment with the respect due a pipe bomb, and make sure your insurance premiums are paid up. And oh yeah, welcome to the sickness!

• Only give the motor what it wants, when it asks for it. Learn to speak it's language and never try to impose your will.



• If you receive a tune-up or advice from one individual, stick with that one program. Fuel tuning is such a black science with so many different ideologies that mixing and matching ideas and components is a direct route to the poorhouse --- or worse.



• When the car shows an overall fat condition (assuming all cylinders are even), always try to burn the excess fuel through added load rather than leaning it by upping the percentage or taking volume away.



• Keep your tuning changes subtle. Never go more than .003" at a time in nozzle size, and never go more than 2% in mixture or 2 degrees of mag at a time.



• When mixing fuel, always use a hydrometer that corrects for ambient temperatures. Nitro mixtures are only true at 60 degress F. Also remember that alcohol tends to overpower nitro. A rule of thumb when mixing 10 gallons of fuel; one (hydrometer) beaker of alcohol is worth approximately 1% of mixture.



• When mixing fuel, always do it in the car's fuel tank, and when adding alcohol try and do so between splashes of nitro. Aerate the brew thoroughly before checking for percentage.



• Once a fuel motor gets hot, it's nearly impossible to bring the temperature back down by fattening it up. This only turns it into a mini blast furnace. Make sure your idle temperature never exceeds 180 degrees at the cylinder head before the car is staged.



• Never take anything for granted. Until you've got a handle on your combination, the oil pan should be pulled and bearings checked every time the engine is put under load.



• Every time the engine's started, all torqued fasteners should be gone over and all measurements such as valve lash and clutch pack gap checked and adjusted if needed.



• It's a very special person who can both tune and drive at the same time (I'm not one of them). Don't bite off more than you chew. It's usually better to focus on one aspect of the race car rather than being compromised by the pressures of doing both.



• Finally, re-learn the meaning of the word "normal". For instance, if you run a gasoline or alcohol engine and pull the pan to find flakes and chips laying in the bottom, you're faced with impending doom. A certain amount of this is considered "normal" with a fuel motor, and learning how to read this debris is a critical part of the learning process.

OK, so you've buttoned it all up and and it's time to light the beast for the first time. The first step, before you attempt to have the motor actually run on nitro, is to get it going on the "squirt bottle", which is filled with gas, not methanol.

This is a little tricky the first couple of times you do it but it's important to get it right because the idle RPM you attain on the squirt bottle will determine the amount of air gap the butterflies are going to require in order to achieve a running idle speed somewhere between 2000 - 2500 rpm. Set the butterflies so that your squirt bottle idle speed is between 2500  - 3000 rpm. It'll automatically drop about 500 rpm when you switch over to the good stuff.

With the air gap set, the barrel valve can be adjusted. Aim for a 92% leakdown. In lieu of a leak tester, the valve can also be set by eye.

Remove the main inlet line and shine a flashlight into the hole. At the top of the spool (or barrel) you'll see a small "fang". Start by adjusting the valve so just the fang itself is visible. Then open the valve by rotating the adjustment turnbuckle until a small crescent shaped opening appears above the fang. If you think of the hole as a clock, you want to have the crescent span from the 11:00 - 1:00 positions. It's not precise, but it'll get you close enough to actually start the engine.

Achieving proper idle quality is critical. If the motor is too fat, it'll never build any heat. Too lean and you're looking at a sure meltdown when you hit the throttle. Once the motor is running on fuel and cylinder head temperature begins to come up (using the scientific "fingertip" method), all eight cylinders should be "misting" slightly out of the pipes.

At this point the brake should not be engaged and the rear tires freewheeling with the car up on jackstands. If the pipes appear dry at this point you can fatten them up by opening the barrel valve a small amount, generally one flat at a time until the desired effect is achieved. Be patient when adjusting the valve as subtle changes may not show instantly.

If on the other hand the motor is blubbering and spitting fuel out of one or more pipes, you've got to back off on the barrel valve until they begin to dry up. (Note: Sometimes an overly fat condition can be traced to a stuck or too heavy idle check valve (spring) or obstruction in the idle return line. If two or three flats won't dry up the motor, look at the check valve and inspect your plumbing.)

Once the freewheel idle has been established, it's time to lock up the brakes and load the motor against the clutch. If you've got the balance between clutch stall speed and barrel valve opening correct, the pipes should dry up when you get on the brakes, and if you're really sharp, you'll get an occasional lick of flame from the number six exhaust pipe.

The last step before shutting her off and towing to the starting line is to whack the throttle once or twice to make sure the motor responds and comes up cleanly. Whenever you open the throttle on a fueler, be sure someone is tightly holding onto the brake handle. You never want to buzz one of these things unless there's a load against it.

Assuming the device you've created is able to complete a burnout, back up, and put down even a partial run without any major destruction --- consider yourself a flaming success if you've gotten this far --- the next phase is to read the spark plugs and upper rod bearing shells.

Reading bearings in a fueler is a lot like reading the plugs in an alky burner, or in other words, they only tell you when you've gone too far one way or another. If you've got a lean condition, or a cylinder sees a period of detonation during a run, the bearing will squish or form "lips" at the point where it contacts the rod journal of the crank.

There are two ways to measure this "squish". The first is with a ball micrometer, a device intended to give accurate thickness readings over a radius. This is as simple as measuring the squished part of the bearing and comparing it to an unsquished portion of the shell.

The other method entails using a caliper to measure the width of the shell. As a bearing squishes the material has to go somewhere, and in the case of a bearing shell, that's out to the sides.

Conversely, spark plugs tell a very visual tale of what's going on inside the combustion chamber. When you pull the plugs after a run, the first thing you'll notice is whether or not the ground strap has been affected by heat. Too lean a mixture leads to the ground strap being nearly vaporized, burned down to a nubbin on the end of the plug. If the ground strap is completely intact and barely discolored, you can assume that particular cylinder hardly worked during the run.

By making changes to the port nozzle stagger, you can fatten or lean any cylinders which show temperature extremes at the plugs. If you see a combination indicating cylinders that are both hot and cold, assume the hot cylinders got that way by carrying the load of the non-firing cylinders, and work towards getting the cold ones to fire. (Note: This is also a sign the blower has gone away completely).

There are two ways to tell you've achieved optimum efficiency in any given cylinder. The first is the ground strap just begins to "fuzz" back, with only the sharp edges at it's very tip showing any signs of melting. Second is reading the threads of the plug --- this applies to iron headed engines only (the scope of this story). Look for the first three threads of the plug to show slight discoloring (referred to as "three rings of heat" and an accurate representation of any given cylinder's thermal efficiency).

The goal is to get all eight cylinders to produce the same amount of heat in the plugs after a full run, and let me tell ya, this is a whole bunch easier said than done ! This is probably the single key element to tuning the engine itself. Once this optimum balance is attained through the juggling of port nozzles, getting an accurate tune-up through blower, mag, mixture and clutch becomes a much simpler process.