Shit Happens

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Problems & Fixes:

bulletIntake gasket lets go... water in the oil... bummer
bulletValve spring breaks... it's what 600lbs of spring pressure will do at 7,800RPM
bulletTransmission replacement... new stronger motor needs new stronger transmission
bulletFuel starvation... insufficient anti-slosh baffles... not an easy fix
bulletBroken crank... my fault.  Did not tighten the damper bolt... breaks the crank at the first radius according to experts... and they were right!
bulletDifferential mount torn from frame... turns out that drag racing is deleterious to drive train health... duh
bulletLoose ball joints...  Changed them to see if they were causing vibrations... they weren't (see worn wheel bearings below)
bulletWorn wheel bearings... was wondering why the car vibrated.  New wheel bearing all around fixed it.  Smooth sailing now
bulletRR wheel bearing carrier wrong size... fact: bearings wobble if the press fit isn't... And who knew about Loctite Green?  Easy fix once you know about LT Green.
bulletNew sway bars... that actually work!  Rubber frame mounts had too much give.  Sway bar didn't take action until car almost rolled over.  Hard mounts good, soft mounts bad.
bulletCompletely worn out and dangerous shocks...  QA-1's adjustables to the rescue
bulletRuined cam shaft... three different sets of lifters collapsed at different times.  The cam shaft finally cashed it in when the third set collapsed.  Note to self, "Change the lifters BEFORE they collapse!"
bulletOngoing lifter swap... every 2500mi's.  See "Ruined cam shaft" above.
bulletConstant fuel filter cleanout... will the fuel cell foam ever stop clogging it up?
bulletSad tail of a broken windshield... mounting screw causes crack right up the center
bulletTuning for altitude... turns out that EFI does NOT compensate.  Crafted 4 EFI programs, 0. Sea level, 1. 5K ft, 2. 10K+ft, and vallet (won't run over 2K RPM)
bulletRework heads... new valves & guides
bulletStarter motor parade... killed three stock motors plus one 4:1 hi-torque motor before realizing they were not up to the task of turning over a 514CID motor with 600# springs and 32deg initial advance
bulletDim taillight saga... tried every LED bulb on the market that claimed blinding brightness.  Still pretty dim. 
bulletDim headlights... substituted higher wattage bulb.  Better but not great.  Can't go to even higher wattage without rewiring.
bulletWheel alignment... ruined several $1,200 sets of tires due to bad or slipped alignment.  Fabricated alignment tools so I could check alignment in my garage.  Problem solved.
bulletExplosive ammeter... fire under the dash caused by bad wiring to the ammeter.  Whoever thought it was a good idea to run high amps behind the dash should be shot.
bulletBad tach... hey, what can I say?  The instrumentation is original Lucas and Smiths English gages.
bulletShattered axles... did I mention that drag racing is hard on the equipment?  Came back 3 of 4 times on a flat bed.  I don't drag race much anymore.  Wife got necklace made from axle shard for Xmas... true story.
bulletWrecked differential case... did I mention that drag racing is hard on the equipment?  Had to go back to steel case away from lighter aluminum model.  New 3.27:1 gearing from 3.73:1
bulletBrake upgrade... original Ford brakes were clearly not up to the task.  Fabricated mounts for Wilwoods all the way around.
bulletBody work / paint... spent 5mo's reworking the body panels and painting everything.  No experience to speak of.  Very scary but the result was good.

 

Some of the above listed problems get special pictorial essay treatment (below).  Others are enshrined on the "Wall of Shame" in my garage.  Still others made the list without amplification.  Of course, the list is not complete... and will never be complete as anyone who owns a high performance hotrod can attest.

1. Failed intake gasket

Almost right out of the chute, water was detected in the oil, which usually means intake gasket failure or worse.  Fortunately, it was the gasket (picture below).  Keith Craft Racing, the engine builder was contacted and to his credit, he offered to fly out to my house 1500mi's away to personally fix the problem.  While that would have been easiest for me, I decided to take a crack at changing it out before calling in the professionals. 

Long story short, a new gasket was successfully installed and all was good... for a short while.  Then it happened again!!  CRAP!  Ok, this time the word went out on the Superformance Cobra Owner's Forum (SCOF).  Seems that others had the same problem.  RT, the SCOF moderator, took up the challenge and called Felpro gasket company directly and just happened to get that particular gasket designer on the phone!  What a stroke of luck.  The Felpro engineer recommended a change in part number to a gasket with metal core.  This particular gasket doesn't show up on any radar screen that I know of,... not Summit Racing, not KCR, not JEGS, not anywhere.  Anyway, the world has been notified of the fix for 385 series Ford engines with aluminum heads and cast iron block combinations.  To date, the new gasket is doing the trick.

Induction stacks and manifold removed. Engine valley showing 5-8 intake ports.

Damaged intake gasket next to #1 intake port. All fiber gasket failed twice before gasket with steel mesh center was located.

Heat cycling caused manifold to move, which tore the unreinforced gasket. Water leaked into the oil... instant chocolate milk!

Induction stacks on the bench ready to be reinstalled on top of the engine. 58mm stacks with 55lb/hr injectors. Made by TWM

2. Valve spring failure

About 5K miles into the new engine's break-in period, it started making noise in the valve train.  Scott's sharp eye spotted the problem... the #6 intake valve outer spring had broken near its lower tip.  Valve lift on this engine is 0.728" (enormous).  Spring pressure at full valve opening reaches 600lbs (ditto).  The large spring pressure is necessary to snap the valves shut at redline (7,800RPM).  Brodix circle track springs are good springs and no, this should not have happened.

The biggest PIA was cleaning the engine of all metal shards... drop / clean the pan, clean upper head area, make sure nothing dropped into the cam bearings or onto any cam lobes.  Other casualties were the #6 intake rocker and the #6n valve stem.  BUMMER!!  I guess one just has to smile and put this one into the "shit happens" category.

Shards from broken #6 valve spring. Found in oil sump. Fortunately, they missed the cam shaft on the way down and didn't get sucked up into the oil pump

Rocker roller bearing was damage when the spring bound after breaking... $$$

Tip of #6 valve mushroomed... $$$

 

3. New stronger transmission - Tremec TKO 600 RR

One blast down the drag strip at WOT with this new monster under the hood, it became obvious that the original transmission (Tremec TKO3550) would not hold the power for long.  It also had an annoyingly tall overdrive gear.  The problem was solved by installing a new 5-speed manual built for high HP (Tremec TKO600RR).  The road race model selected is a close ratio box with an evenly-spaced overdrive step.  The only modification for fitment was sawing off one of the lower tranny mounts to clear the Cobra's frame rail.

At the same time, the original 3.71:1 Ford 89.8" differential was re-geared to 3.27:1.  This put the 1-2 shift point at about 62MPH, which on the surface seems too fast.  However, the car weighs only 2600lbs and engine torque tops out at around 700lbs.  There is WAY more torque than required to light the tires in the bottom two gears.  The taller rear gear has proven to be more street driving friendly without compromising performance out of the hole.

Transmission comes out from the top after removing seats and tunnel.

Had to saw off one of the differential mounts in order to clear the center frame rail.

Stabbing the transmission back through the clutch disk and into the pilot bearing is a manly art. Takes both muscle and precision.

 

4. Fuel starvation fix - Serge tank

It became apparent very quickly that fuel pressure failed on hard acceleration when the tank was less than half full.  On further investigation, it was discovered that the fuel tank slosh baffles were completely inadequate even for carbureted engines, which have float bowls to buffer temporary loss of fuel pressure.  EFI, on the other hand, can't stand even a short interruption in fuel pressure. 

Two fixes were tried.  The first thought was to stuff the tank full of fuel cell foam... what a disaster!!  Not only didn't it prevent fuel slosh, which uncovered the fuel pickup causing fuel pressure to drop, the foam proved impossible to remove completely from the tank.  To this day, the primary fuel filter becomes clogged with foam shards after only a couple hundred miles.  The stuff seems to replicate in the tank.  What a PIA to clean the filter that often.  Note to self, "Fuel cell foam = bad.  Do not use."

The second approach pictured below solved the problem.  Basically, an auxiliary 1gal surge tank was fabricated and bolted to the frame under the RR fender.  A small fuel pump (Holley Red) was installed to fill the small surge tank continuously from the main tank.  Overflow from the surge tank was plumbed back into the main fuel tank via the vent pipe.  The main fuel pump (Aeromotive A1000) that feed 40PSI to the fuel rail takes gas from the 1gal surge tank.  Return fuel from the fuel rail is plumbed back into the surge tank.

In short, there are two fuel pumps.  Pump #1 circulates fuel to the 1gal surge tank from and back to the main fuel tank.  Pump #2 circulates fuel under high pressure to the engine's fuel injection distribution rail and back to the surge tank.  These two fuel loops guarantee the main fuel pump pickup will never see air unless the main tank runs dry.

Fuel 'anti-slosh' tank shown with fuel rail feed & return ports (blue) and fuel fill & return ports (brass). Tank is 1gal made of 3/8ths aluminum pipe and plates.

Mounting flange with two holes welded to tank and bolted to frame rail in RR wheel well. Frame and tire protect anti-slosh tank in case of crash

Bracket bolted to RR upper frame rail just behind the tire. Anti-slosh tank bolts to this bracket and the descending frame rail. Very secure and safe mount

Main fuel feed line at bottom tank outlet. -10AN line goes to Aeromotive A1000 pump then fuel rail. The -8AN return line from the fuel rail is connected to the tank at the top directly above the larger feed line

Very tight fit for the main fuel pump and primary fuel filter next to the differential

Better view of the anti-slosh tank mounting, fuel lines, small tank filler pump and larger EFI fuel delivery pump