Diagnostics Part II

When I wrote the other article about Diagnosis, I was experiencing a problem with my Olds. It wouldn’t idle. It would run fine off about 1500 rpm up but would die below that. At first I thought the problem was dirt in the fuel again. Turns out it wasn’t this at all, and I was a bit miffed. I spent a couple of hours rebuilding both 1850 Holley 600’s for nothing. During that process I became suspicious of my original diagnosis because I didn’t find much debris in the carb float bowls, or in the needle and seat assemblies. 

So the next logical step in the situation was to bolt the carbs back on after rebuilding them to see if I had exorcised the demon or not. Well I was not surprised to find that the demon was still there. The car ran exactly the same. It was just as if the idle circuit was completely turned off.  So I decided that maybe the 1850’s had circuits in them smaller and more prone to plugging up that did say any of my 4150’s. I had a spare 4780-3 4150 kicking around my shop that came off the race car. I also had a single four barrel top for the Offy Tunnel ram on the car now. I also wanted to see how the car ran with that top on it. After remaking both float bowl hoses, fabricating a new throttle cable bracket and a return spring bracket I put some fuel to it. I always pressure test the carb before I light it up don’t like fuel squirting all over the place with the engine running. This, by the way, is another reason to run an electric pump over a mechanical one, you get to say when the carb gets fuel and not the other way around. It’s also a great theft deterrent too. They might get your ride started but if they don’t know where the pump switch is they ain’t getting too far. In the case of my Olds they couldn’t even warm the damn thing up before it was out of gas! LAMO!  

Alrighty so no leaks. I lit the motor and it still did not want to idle. I didn’t think this combination would fix the problem I just wanted to swap the dual 4’s out for a single four. Now I’m thinking this carb was just rebuilt too so I know that all the gaskets and stuff inside the carb is all on the same page? Maybe. I’m getting ahead of myself here. I decided that the ignition system was worth a look. Mainly due to the fact that the distributor cap had been on there for over a year, as had the rotor. I’m running an MSD Pro Billet distributor on it with the small cap and rotor. I pulled the cap off and the center carbon electrode in the cap was toast. The contact strip on the rotor had a semi-shitty looking black spot on it where the cap had been shooting lightning bolts down to it. I ordered a new cap and rotor from Summit and got it a couple of days later. I love these guys.  Anyway, I installed the cap and rotor and cranked it back up. It was running a little better. It kinda, sort of wanted to idle now but still wasn’t smiling at me much. Ok so I decided to pull a spark plug. These were older than the cap and rotor and they looked it.  These were NGK BKR6E’s. I went to a heat range colder, BKR7E. Remember NGK heat ranges go colder with a larger heat range number. This is a V-groove plug and they have worked great in my race car and this engine as well.  I gapped them out to .041” too.  MSD won’t give plug gap recommendations per se. They have some suggestions however. I am running the HVC II Blue coil on the system so I have plenty of spark energy; I decided to run a wider gap. The more plug gap you have the more load it puts on the entire ignition system. It also helps get the mixture burning sooner and in most cases easier too, kind of a tradeoff. This is something you are gonna have to decide with your particular ignition set up. Most MSD systems in good health should smile at you on a .040” gap. 

This made quite a bit of difference. The motor fired up a lot easier and it was running about 50% better than before so I felt like I was getting closer. Sometimes when I get to a cross roads with a problem  I’ll just say pass and not mess with it for a while. My mind runs scenarios in the back ground while I’m trying to ignore the problem. So it dawned on me one morning drinking a cup of coffee.  First let me say that I pulled the valve covers off of it and checked all the valve springs to see if any had broken. They all looked good. I checked the timing and it was exactly where I had set it initially. I did a check for carb and manifold leaks. Found none anywhere. I rolled the motor over by hand with the plugs out and watched the rocker arms and valve springs, all of which looked fine. I did a compression test on it and had two cylinders that were low by 10 lbs. but nothing to worry about. One was 5 lbs. above the rest. These inconsistencies can be caused by cranking speed, due to a battery charge state, valve lash adjustment etc., so I didn’t jump to any conclusions. I wasn’t about to tear the heads off of the engine because of a 10 lb cranking difference in compression. Usually if the compression is bad in a cylinder the motor will run rough or even drop the low cylinder out of the firing sequence. My engine wasn’t doing this. 

So by running a compression test that told me a lot about the engine. It says that the valves and rings are good, and the timing was on and it was rock steady too. You have to start covering bases when you are chasing a problem like this. Then all you have to do is consider the symptoms and start ruling things out. I decided that I probably didn’t have any internal problems with rings, valves, broken valve springs, so I got to cross those potential problems off my list. One thing kept hitting me over the head and crashing into my face head on and that was that the engine was behaving like there was no idle fuel feed to it. 

Today I went back outside and pulled the carb off. I took the base off of the carb. If you are running a 4150 double pumper of any sort pay attention to this: Holley’s have about 4 different styles of base gaskets and all of the damn things will fit the bottom of the carb. That doesn’t make them right however!  4150’s like the early versions I have use a rudimentary secondary idle system in them. It’s not as sophisticated as the new four corner idle carbs on the market now days. However there is a transfer passage that runs from the front end on the primaries around back to the secondary idle orifices. Some of the gaskets have a hole that allows both holes to show thru the gasket and others only allow one of the two holes to show. These holes are on the very front of the primary side of the throttle base. They are located on the corners of the throttle bore radius on each side. If you install a base gasket that covers up the outside hole you have shut off idle circuit fuel and the carb will act like it has no idle system. Your idle mixture screws won’t do Jack Shit. I found this out the hard way on the race car one day. I rebuilt the carb and bolted it back on the motor. The car wouldn’t idle when I started it back up. Removing the base plate I found the problem. Changing over to the other gasket solved the problem. You’d think I’d have remembered it wouldn’t ya? Well I did, but I overlooked this when I was putting the carb back together because I had my mind on something else, something I should not be doing. What the hell I’m human. Well I found the exact same problem with the base gasket that was on the carb I had just rebuilt. Clumsy Me.   I swapped the gasket back out and installed the carb on the car. I fired it up and it still didn’t want to idle real well, but it was a hell of a lot closer now than I’d had it since this problem started. I ran one of the idle mixture screws in until it bottomed and it didn’t change the idle speed much. I tried the same thing with the other side and the idle started decreasing. So I put it back where it was and opened up the other side. Holley says a baseline setting is 1 ½ turns out from lightly seated so I opened up the shut down side one and half turns and the idle picked up above what it had been! Good sign! So then I bottomed the other side and ran it back out one and half turns. Now the motor was going about 1600 rpm. I closed the curb idle screw down in small increments watching the tach. When I got it down to 1100 rpm it was back to its cackling, gravel throated, bluesy, Olds voice. Love the way this motor sounds. Throttle response up from idle was excellent. It’s still pulling fuel thru the transfer slots but that’s because this carb was on a car with a big roller cam in it that had 4 inches of manifold vacuum and had no idle needle adjustment. One fix for it is to drill a small hole 1/8” or smaller on the leading edge of each throttle butterfly. This allows more airflow which reestablishes air flow thru the idle circuit. It gives back some idle needle adjustment. However on this engine that isn’t needed or at least the holes are a bit too large for this engine. I’m gonna install some undrilled butterfly’s in it and it should get the idle needle adjustment spot on. This will allow the throttle blades to be lowered back over the transfer slots so they are out of the picture. They aren’t supposed to run curb idle in the first place. 

So now the motor is happy again. And when she’s happy I’m happy. Funny thing about that ya know?


What It Takes to Run Top Fuel.

For all of you people that dig drag racing and wondered what Top Fuel is like here’s a little ditty I put together so you can see what a Top Fuel engine is like, how it’s built, and how expensive top fuel cars are to campaign. To do it on your own is next to impossible unless your last name is Trump.

  The cylinder block; Top fuel is so hard on parts that the block has to be robust in the exponential form to withstand the internal forces.  It has been estimated that these engines produce between 7000 and 8000 horsepower. No one really knows because a top fuel engine would shake a dyno to pieces in short order. There’s just no dyno’s that will handle one of these monsters. Besides that these motors are way too expensive to sacrifice one on a dynamometer. Back to the blocks, they are forged units. John Rodeck has pioneered top fuel hemi blocks for years.  Rodeck says that the block is first forged with a massive 8000-ton hydraulic press using a single die done is three strokes to produce the basic structure. After that, machining takes the block from 250 pounds down to around 100 pounds.

   After initial machining the block is heat treated using a specially made Rodeck-designed oven that bakes multiple blocks in one shot.  Then the blocks are bolted down in a specific way and final shaping and head bolt holes are machined to tolerances of plus or minus .0005” inch. That’s really tight! The block is them moved over to another CNC machine and it’s finished up. It takes approximately 12 hours to finish a block. Each block is custom made to the customer.

 Crankshafts: Bryant Racing Crankshafts produce fuel profile crankshafts on a billet assembly based on bearing spacing off of Chrysler’s 426 Hemi engines. The cranks are machined from 4330BM Timken steel. It takes Bryant 60 hours to produce a fuel crankshaft which includes post-manufacturing treatment process. These cranks along with having stress-relieving, and nitriding processes done are also cryogenically treated (frozen).  Each crank goes for around $3800.00 each. This also depends upon what the crew chief specifies on the crank being made.  A typical crankshaft usually will run anywhere from 12 to 15 passes. High dollar teams replace them after 12 runs.  This is assuming the crew chief gets the tune ups right. If he doesn’t he can kill a crank in one pass. Yeah these motors can be that hard on parts.

  Pistons: Pistons in top fuel motors are the sacrificial lambs of the engine parts. Nitromethane is just so violent it takes it toll on the pistons. Bill Miller Engineering makes some of the best fuel pistons on the planet. The pistons are made from an aluminum alloy 2618-T61. The front four pistons are down .030” compared to the back four, which makes average overall compression run about 6.8:1. The pistons are subjected to a low temperature hard anodizing process. Pistons made this way last about twice as long as they have in the past. How long is that? Well a piston can last from one run to 5 depending on the tune up. Teams usually buy pistons 40 at a time, price on that quantity is $62.50 per piston, or $2500 for a 40 piston lot. Nothing cheap about these engines. BME also manufactures wrist pins. Top fuel and funny car nitro engines produce forces on the wrist pins of as much as 50 tons. There are very few materials what will withstand this sort of force. BME uses VascoMax C-300 an exotic thusly expensive nickel-cobalt-titanium steel  “superalloy” with very high tensile strength, (294,000 psi) and an extreme fatigue endurance limit (one billion cycles at 125,000 psi).

    I’m not gonna go into the entire engine assembly, I wanted to get into some of the more astonishing data about these engines. Just know that the rest of the pieces in one of these motors is designed and built like the above pieces, with corresponding prices per unit piece as well.  Cylinder heads for example are usually Alan Johnson pieces which are a true work of art. They are CNC machined and ported so the heads are repeatable for each customer. Most feature a 2.45” intake valve and a 1.90” exhaust. These are the AJPE Stage VI Hemi Heads. Set up for a 4.187 bore diameter. A set of bare heads goes for $6850.00.  A fully assembled and finished set of heads goes out the door for $9000.00.

Camshafts: Ok here’s where the fun starts. Crane Cams makes top fuel cams on a 2.125 diameter base. The intake duration at .050” lifter rise is 298 degrees, and the exhaust is 296 degrees. Lobe centers are 112-114 degrees. Lobe lift is usually between .478 and .500” lift at the valve depends on what rocker arm ratio is being used. On the intake side they can run from 1.57 to 1.75:1. The exhaust side runs between 1.52-1.65:1. So doing some simple math let’s take the .500 lift cam lobe and multiply it by 1.75 on the intake side and 1.65 on the exhaust. Multiplying .500 X 1.75 yields .875” lift on the intake valve and  1.65 X .500 gives us .825.” That’s got the valves darn near an inch off their seats!  Push rods are huge. Big block Chevrolets back in the early days of 427 big blocks uses some 7/16 diameter pushrods on the L88 motors. Top fuel pushrods are 9/16” in diameter! Opening pressure on the exhaust side of a running top fuel motor is tremendous. In fact some teams are using solid steel pushrods on the exhaust sides.


If you think your SUV gets poor mileage then read on! 

  Fuel Delivery:  Because nitromethane only contains roughly ¼ the energy content of gasoline you have to wash a lot more of it thru the motor. Nitromethane brings its own oxygen into the engine with it unlike gasoline which has none. Gasoline’s stoichiometric air fuel ratio is 14.7:1. Or 14.7 parts of air to 1 part of fuel. Nitromethane’s Stoichiometry is 1.7:1. This means we can run it just about direct one to one air to fuel ratio. This takes a tremendous fuel system.

The fuel pumps are made by Sid Waterman. They are driven off the front end of the camshaft. The one of choice is called a “Mega Bertha”. These are billet assemblies set up in four sections. These fuel pumps can deliver more than 112 gallons of fuel per minute at 600 psi!  Most teams run them at 92 gallons per minute, and during a pass this equates to 1.3 gallons of fuel per second!  Top fuel dragsters carry 18 gallons of nitromethane on board, and more than 8 gallons of it are used up during the burn out and the staging process. Most of the balance is used up during the pass!  So these cars are burning almost 18 gallons of fuel in less than a quarter of a mile! Top fuel and floppers are limited to 1000’ under throttle.

And you thought your SUV got shitty mileage? To get this amount of fuel flow into an engine takes lots of injector nozzles. Usually 32 or more nozzles are used. 8 injectors are in the hat, another 8 located in the intake manifold and 16 more located in the intake ports. An onboard computer is used to sequentially turn on these “down nozzles.” It is linked to the clutch and other data sending areas. And you thought dragsters were simple?

In order to light off this sort of mixture takes one hell of a sparker. MSD’s 44 Pro Mag is the only one being used today. Not that it’s a bad one on the contrary it’s a great unit. Personally I don’t think the old Vertex and Schiefer Magnetos of yesterday would light off the fuel cars of today, just isn’t enough  spark energy in these older units. The MSD Pro Mag 44’s produce around 44 amps of current along with extremely high secondary voltage. Fuel motors have sixteen sparkplugs not 8 like a normal V8. So they run two front driven magnetos. If you have wondered why there are two red headed Pro Mag 44s in all the fuel and floppers that’s why.

Top Fuel and Top Fuel Funny cars are the hardest accelerating cars on the planet. They are every bit as sophisticated in their own right as a formula 1 car or any other race car for that matter. There’s nothing that sounds like a 500 inch hemi motor on 90%. Nothing has the throttle response, the sound, the idle it’s the ultimate form of the reciprocating spark lit, piston engine. No other engine on the planet makes anything even close to the power of what a fuel motor is capable of. It’s often trick to equate how many horsepower per cubic inch a motor can make. Chevrolet was the first American V8 to make a horsepower per cubic inch when the 283 cubic inch 283 horsepower fuel injected small block came out. Top fuel nitro motors make 16 horsepower per cubic inch! Sixteen times as much as the little 283 did back in 1957!

Just a little information for you.


References are:

Drag Race Technology: Top Fuel: So Much Power, So Little Time by Wayne Scraba.

Equipment Manufacturing:

Bill Miller Engineering

Bryant Racing Crankshafts

John Rodeck

Crane Camshafts

Sid Waterman

Alan Johnson

The Little Girls of Midnight

The demons of sleeplessness are upon me.
Try as I might I cannot make them flee.
The white pearls of Midnight melting.
In my mouth their way of helping.

I find myself alongside a car.
Talking with friends inside that are.
Really unknown to me.
A rumbling in the distance like the sea.

A gray-litten fog surrounds us.
Biting, wet and cold thus.
I stand within its embrace.
Cold water runs down my face.

Tiny voices tinkling in the fog.
Catches the attention of my dog.
I turn and see three tattered little ones.
Ahead one of them runs.

She speaks to me in an occidental flavor.
Tiny and pleading with a little waver.
Her way of talking to strangers.
Her idea of evading the dangers.

 My reply to her a bit too curt.
I can see my words have hurt.
Tears welling up in her fathomless eyes.
Despair escapes her in an anguished sigh.

And I feel like a spear’s in my heart.
And I feel like it’s my ill-gotten start.
On this little girls tears.
On this little girls fears.

And so I tell her I was only kidding.
And her eyes are damaged and forbidding.
I think to myself she’s so damaged.
And I see her dirty red sweatshirt so ravaged.

Her little fingers black from digging and pawing.
Through garbage cans and dumpsters clawing.
For food, for life, her existence in this world.
This dirty-faced freckled little girl.

And I touch her red unkempt hair.
A badge of no parental care.
And who could throw this pretty child away?
And who could let her suffer in this way?

She is so tiny and frail.
And her blue eyes so pale.
And I open my arms to all three.
And they all hug my legs like I’m a tree.

And I can hear their crying in muted whispers.
Tiny, disposable humans by someone’s blunders.
And I hug them as good as I am able.
These three in no one’s fables.

The girl with blue eyes looks up at me.
“Don’t forget us mister” she pleas.
Suddenly I’m removed from this place.
And I’m back in my time in space.

I won’t forget The Little Girls of Midnight.
That haunted my dreams last night.
The wistful, soiled faces of plight.
That remains ghost-like in my sight.

 The Little Girls of Midnight.
Will remain with me every night.
For now unto eternity.
The little ones who suffer no amenities.

Dave Proffitt
2:26 pm

Widow Maker

Standing alone on top of the hill.
Rain running down her trunk into the rill.
Wind whistling thru her massive limbs.
Violin sounds given to the winds whims.

Two hundred seventy five feet high.
This forest giant reaches for the sky.
With arms outstretched she begs to feel.
The white clouds floating by to reveal.

A silver storm moon looking thru the trees.
Gilding her looking side silver in the blackness.
The hoary bark with its metallic down.
Blends with her emerald needles around.

 Massive limbs eight feet through.
Radiating out in the canopy anew.
She’s reaching always reaching.
She’s teaching, she’s beseeching.

To leave her be.
For us to see.
She won’t go softly into the night.
She won’t come down without a fight.

 Ten men have tried.
And ten men have died.

To bring down this forest Queen.
All who died at the scene.

She’s not like all the rest.
She’s God’s last test.
A tree of specific genome.
A tree with healing chromosomes.

They call her the Widow Maker.
Standing alone on God’s acre.
This tree is a sacred entity.
Alone with her dignity.

It is said there is an energy field.
That now surrounds her as a shield.
From the folly of man.
Her unending stand.

She sings to the forest below.
Her soft breathy notes that blow.
From her needles and boughs.
She casts her peaceful browse.

Upon the forest visitors.
Anesthetizing to her inquisitors.
Which one you are she can tell.
Which one you are she can smell.

 I’ve seen her standing on the mountain.
I’ve seen her sparkling fountain.
That flows from a small rill at her base.
My dog and I dared a taste.

And afterwards I could understand.
And I could see the deeds dead hand.
And I knew all these things from whence they came.
And these things tugged at my soul and made me numb.

And so I could also understand my dog.
And so we sat down him and me on a log.
And I could speak with him.
And he could speak to me.

And I looked upon the tree.
And I heard her say “now you can see.”
So I asked her if she was indeed grim.
So she told me she had no phantom limbs.

Only because she would not allow.
Removal of her limbs and boughs.
And so I began to see the value of life.
And so I also could see the cause of strife.

The Widow Maker stands unto this day.
She speaks to me in her special way.
My dog whines when she sings.
Her music gives my heart wings.

I think what a miracle of life she is.
I think what a blessing it tis.
When I am troubled I think of her.
Of bad times that are and were.

And she lifts my heart and my soul.
And this world again can take no toll.
Upon my dog and I.
And she gives it all back to the forest and the sky.

 Zephyr and I visit the tree four times each year.
Winter, spring, summer, fall, to clear.
Our minds and to have a drink at her fountain.
Of this mighty tree that stands on the mountain.


Dave Proffitt
1:47 pm