Welcome to my Cobra Replica build blog.
Please contact me if you would like to know more detail as i progress."CR3514@live.com.au"

Thursday, March 15, 2018

Battery Compartment Cover Progress

A bit out of sequence this post, but got some more progress on the Battery Compartment Cover Mould as well.

After milling out the profile in MDF, I've given the cut surface a spray with primer sealer to protect it a bit from moisture absorption.

a few coats and sanding then I'll paint it with a top coat and wax polish it ready to take a fibreglass panel off it.

Only needs to do one. :)  ...one good one .

The Body is On...Again

Finally stopped procrastinating and getting distracted with fiddly jobs and enlisted Mrs.W to help me put the body back on the chassis.

It wasn't without emotional pain or damage unfortunately, half way through lowering it, I had to remove the oil cooler to get the lower oil cooler body opening over the front outrigger bar.
In the process of lowering the body, I forgot to remove a wiring loom earth bolt on the chassis out rigger that secures the inner front wheel arch, cracking the fibreglass and chipping a bit of paint.
Should be an easy repair at some point down the track, but annoying all the same.
Thankfully, Diane is immune to my expletive rants. Thank you truly.



Used bike tie down straps to hold up the body. These make for easy adjustment of the install angle.
Front has to clear everything then body pushed backwards and held against the outrigger while lowering for the body to clear the engine and quick jack mounts that protrude up through the boot floor..

Go !

Oh No, something went crunch.....

I'll clean this up by putting tape over the back of the wound to secure it, then bonding with resin, reshape, then remove the tape and do on the back side before touching up.

Up on the hoist for a panoramic pic and a look to see if any wiring or other items pinched between the body and chassis.

All looks good.

Spent a fair time tweaking the body on the chassis to get it as square and levelled as possible before installing mounting bolts.

Installed the bonnet mounting brace loosely,

Its the black bracket in the background behind the PWM fan controller.

The Fan controller is a corvette part and is pulse width modulated by the ECU to provide variable fan speed based on engine temperature.

Put the bonnet on and packed it up to be levelled to the bonnet opening then tightened up the bolts to the hinge so it aligned with the mounting brace.
then positioned the brace to align with the hinge pivot tube.

Tightened up the brace bolts that sandwiches the body and chassis with the brace.

Attached the bonnet struts and removed the packing.
Next step is to make some hinge pins with removable clips for easy removal of the bonnet when required.

Friday, February 9, 2018

In the boot

After fitting up the radio / Bluetooth / USB player in the boot and adding in the dedicated Battery Trickle Charger, I wasn't happy with the prospect of easily getting a panel to seal access through to the battery compartment which is open air from underneath.

Measured up and made a surround to fit from Aluminium sheet that I could seal to the body with a Wind-lacing & Seal profile and crate an opening I could put an easily removable Battery access panel.

Made up a mount for the radio and fixed to the inside wheel guard.

The battery access surround panel fitted and seals installed.

Battery Trickle Charger located to the Right hand side inside wheel guard.

Boot Lid mounting Cross-Brace installed and wiring for lights and auxiliary power completed.

Amplified under-body Antenna installed.

Made up a bezel for the Shift Hole to finish up from underneath.

Also cut a grommet holder for the reverse light wiring in the boot floor.

The Shift Hole Bezel installed in the Transmission Tunnel.

The Reverse Light Grommet Holder installed in the boot floor.

The floor is about 6mm thickness, to thick for a small wiring grommet to fit in.

Started design and building a mould to make a fiberglass access panel.

Concept for the panel drawn in Sketchup.

Put a CR logo in the panel to add some stiffness to the part.
Panel will be just a few layers of cloth to keep it light.

I then created an inverse mould in Inventor.
For 3D CAM work, I use Inventor to create the STL file I export to CUT3D program I use from Vectric.

Once the STL is imported into CUT3D, its easy to create the tool paths using the wizard.
The Vectric program has a post processor that creates the toolpaths automatically to suit the mach 3 CNC software.

Next post I will add some pics of the MDF mould I milled out for the Battery Compartment Panel and some pics with body back on the chassis now that underneath is completed.

Saturday, December 16, 2017

Aerial View, Wiring up the Body Loom

Started wiring up the Body Loom in the engine bay through to the boot.

Lights, Indicators, Brake, Tail & Reversing Lights, Brake Warning, Hand Brake Warning, Radio/Music player, some auxiliary Power takeoff points under bonnet and boot area.

This pic shows the body colour a bit more true to the actual paint colour.

Saturday, December 2, 2017

A Lick of Paint

Over the last year, the body has been upside down on a pallet.

Sitting on some foam blocks on a pallet with wheels while I jigged up a frame to support the body.

There was several gaps between the body & the passenger, boot compartments, particularly between the engine bay and under dash area where the jointing filler was poorly applied or not applied at all.

Cleaned up all the excess filler, dug out all the loose bits and sanded back,

Fibre reinforced filler wiped in and left to cure.
Once cured, sanded it up and blended with a disk sander.

Spent a fair time also putting in wiring holes for the body looms, cleaning up all the holes for other mounting points etc.

This is the Quick Jack Mount in the boot, drew some lines around the cutout  for a neater finish while it was on the chassis.

Once finished. I'll seal it up with an alloy plate and rubber gasket.

Underside of the above pic;

Same hole, A bit of an improvement.

A bit of a cleanup to finish it and other similar holes.

Cleaned up some of the cut lines on the wheel inner guards to follow the chassis lines a bit neater.

Blended in the footwell steering column shaft exit area.

The lower oil cooler inlet bottom panel had a large bow in it, and it inhibits putting the body on without removing all the cooler assembly.
I also wanted to remove the cooler easily in the event it needed replacing, and to install scuff panel in case of a scrape with a steeper driveway or speed hump..... so i cut it out.

Put in some mounting points for the side vents.
These are Foam or Fiberboard insulation installation discs.
Drilled through the centre, installed a Rivnut, and glued in place with Sikabond.

In this pic, I've wiped Automotive body joint sealer over them.

All the joints between panels have been whipped with the joint sealer to smooth and seal from any leaks to the compartments and finish off the underside a bit better.

In this pic, I've also masked up ready to paint on stone guard on the wheel arch inners.

The wheel arches sprayed with several coats of  Motorspray Stone Guard.
This stuff doesn't go far and I used a can for each guard, about 3 coats each.
Sprays on well with the optional gun fitting and 40psi air pressure.

So after all that, it was loaded up and off to Paintwerks in Moorabin, Melbourne.

It rained all the way and arrived at Sime's paintshop with an extra 20 litres of water on board in the nicely sealed wheel wells :)

Sime doing what he does best.

The colour is PPG Fiat Azzurro Blue base coat, with PPG's LVC104 Enviroflow UHS Clearcoat.

This colour I matched to a photo I like of the original Brittany Blue, or Viking Blue as used on some cobras and mustangs of the same era.

Looks much darker in this pic, its actally quite silvery in the sunlight, and a slight green tinge under Fluro lights.

Here she is back home again hanging on the hoist.

You can also see in this pic where Sime straightened the sill panel area under the drivers side door.
This had quite a bow and ripple in it and was much easier to fix it while upside down and accessible.

Wheel inner guards have been over coated with U-Pol Raptor 2 Pak Urethane Ute Bed Liner.

I will probably use this in the cockpit under dash areas and boot compartment as well.
Having the car on the hoist upside down makes it so easy to work on in the engine bay, cockpit and boot compartment, so i'm doing the body loom and heat shields before i flip it back over and sit her on the chassis.

Friday, September 30, 2016

Engine Started

A big milestone ,
Started the engine, I was expecting the worst, but it fired right up.

The start wasn't without problems though;
Engine was idling at 1900rpm.
IAC didn't function and seemed to get worse.
Rear block off IAC plug was letting air past.
Air leaks from under the quads.
Huge amount of air being sucked through the PCV circuit.
Thermostat didn't start opening till about 210deg, and the coolant spewed out from under the pressure cap shortly after.

Headed back to work to ponder next actions over the fortnight before returning to tackle the issues.

First up was the leaks under the quads, after removing the first quad, i realized that the IAC port machined into the base of the throttle body over hung the inlet manifold.
After looking up the Holley web site, I found they have a plate that installs below the Quad specifically for this purpose, but also that it was supposed to be supplied with the throttle body, a quick search through the packaging revealed them tucked away in a paper envelope the same size as the base of the box, though i didn't realize it at the time.

In this pic, you can see the port overhanging the plate I made to mount the the throttle cable to.

The plate I made to suit the manifold shape didn't cover the IAC port.

Here is a pic of the Holley plate with the extension to cover the IAC port facing towards the right in this pic.

Next up was the amount of air being sucked through the Oil Catch-can and PCV circuit.
After doing some Googling, I found that the original inlet manifold PCV circuit entered the manifold behind the throttle body, so got my old manifold out for an inspection and found the tube internal diameter is 2.5mm, The hose and fittings from the PCV to the catch-can and then to the quad on my setup is -4AN, (1/4" - or 6.35mm).
This was causing way to much air through the breather port on the rocker cover, so i machined up a restrictor to fit inside one of the port fittings on the catch-can.

This is a -4AN orb fitting, which i drilled out the centre to create a ledge for the restrictor to nest into.
The hose fitting that screws on to the port fitting is slightly smaller hole diameter, so the restrictor is locked into place.

This is the Oil vapor separator (Catch Can).
The PCV circuit is located beneath the valley plate on the LS3, then hose to Catch-Can, through the oil separator and back out again to vacuum port on the forward throttle body.

 The restrictor is in the Oil Catch-Can fitting on the left as it exits to the throttle body. (left most arrow)

In this pic you can see on the right throttle body the PCV return fitting.

Also on this pic is the modified Rear IAC port block off plate, with a bolt now threaded through it to apply pressure to the plunger  so air cant leak past.

The most thought provoking fix was the coolant leakage under the cap.
After reading many blogs, I found some information on the LS cooling circuits, including the suggested fix for the LS3 style thermostat not opening.
Basically, on the LS3 thermostat, there is no coolant bypass holes in the pressure by pass plate as on the LS1s., and Ls1 thermostats dont fit LS3 pumps.
The LS3s rely on coolant flowing out the heater circuit on the engine side of the pump and back in across the thermostat on its return to the pump.
I had these ports blocked off as i don't have a heater.
The thermostat would eventually open, but at a much higher engine temp.
The other suggestion on Pirate4x4 was that LS Header tanks should be on the "Low Pressure" side of the cooling system due to higher pressure in the circuit and pump flow pushing the pressure cap of its seat.
My header tank was plumbed straight off the pump outlet.
A Good Read.

So some plumbing changes now have the Header Tank plumbed in to the Heater return port with Radiator bleed and Head Steam Vent tubes providing continual circuit of water over the thermostat.

All coolant problems now solved with the revised plumbing and thermostat opening at correct temp and timing.

Last problem was the IAC.
I tested it as per Holley EFI forum suggestions, by changing the "Parked" settings on the ECU to 0% and then 100%, the IAC didn't budge from about 50% open, and when the engine was running, the IAC would read as closed, but would hover around the 20+% open.

I was thinking Holley IAC, Holley Wiring Loom, Holley Dominator EFI, should work together until it dawned on me I had an LS2 spec loom and so it would be to suit a GM type IAC.
This was confirmed when I found that the Holley IAC is a Chrysler type. A check on the wiring diagrams confirmed the difference between the LS2 and Generic Holley looms.
Same Connector, Delphi 150.2 4 pin, but the pin assignments are different for the stepper motors.

A simple change of pin locations on the Holley Dominator P1B connector on the loom and the IAC was working perfectly.

I changed the pin positions on the ECU end as the pins remove very easily by pushing a locking tab and then pulling on the wire.

The Delphi 150.2 plugs however are a pull through wire type connector and  i would have had to get new terminals and rewire.

I also finished my aluminium version of the inlet tray,
Mark Nugent from www.marknugent.com.au made it using the fiberglass part I made awhile back as a buck.
I thought the fiberglass part looked a bit heavy but I was happy with the shape and overall look.
Marks work is simply amazing, checkout his Web page, Facebook page and Youtube.

 Set the part up on the router and cut the location mounting holes.

So..... here it is, some video of the engine running.

Wednesday, March 30, 2016

Bits and Pieces

Slow progress over recent times, with work and waiting on bits and pieces or modifying to make them work.

First up was an IAC (Idle Air Control) block off plate so I can remove the unit from the second throttle body.
The IAC is a stepper motor and adjusts to the ECU commands to maintain idle requirements by pulling a plunger out of the throttle plate bypass channel letting more air in, or closing up to limit the air through.
I only need one IAC to operate Idle control, but leaving the second one in place unconnected means the IAC will not block the second bypass with enough force to ensure no leak past.

Programming the ECU to operate 2 IACs was beyond me if at all possible.

The IAC mounted on to throttle body.

In this pic, you can see the throttle plate bypass port with the hole that the IAC plunge blocks or opens as the ECU controls required idle air volume.

The IAC stepper motor.
You can see the plunger end that fits in to the hole in the port.

In this pic, you can see the tapered hole the plunger seats in.

I bought an IAC block off plate from Accufab to replace the motor and block the hole but it didn't fit.
The seal boss didn't fit in the port, The mounting holes don't line up on the face, and the hole plug was 3mm short of blocking the bypass hole.

I'm not sure if there are other IAC versions so close in design, but the Holley IAC is identical in measurements to the LS1 unit from GM, that I assume its a standard part, so maybe the block off plate was machined wrong, either way it didn't fit.

After pondering and considering the part a waste of time and money, I decided to machine it up to fit utilizing the IAC plunger and compression spring and the Accufab block off plate combined.

So, here is the new improved version.

Machined the 'o' ring boss down so it would slide in to the TB recess.

Then I discovered the mounting base wasnt square to the shaft, so faced the inside of the mount.

Then shortened the shaft and drilled and machined a hole for the spring and plunger to be inserted.

In this pic you can see the misaligned mounting holes.

so, rotated, drilled and tapped 2 new holes.

Job done, hope it works.

The ECU I'm going to use is the Holley Dominator EFI, in conjunction with Holley's harnesses.
The engine harness is for an LS2 as its the nearest fit in terms of sensors and connections excluding the MAP sensor. Easily fixed with an LS2 to LS3 map sensor adapter pigtail.
It also has standard GM Air Inlet Temp (AIT or Manifold Air Temp) sensor plug.
But there is no Alternator circuit in the loom.
The alternator is a Mitsubishi 2 wire 140 Amp (Standard on AU version LS3's and probably some others as well).
The plug terminals are L and F which I understand to be "Line" and "Field"
The F terminal is for the original ECU and BCM to monitor alternator output (via PWM signal) and compare with battery condition.
The ECU then pushes a PWM signal back via the L terminal to set the required Alternator output voltage.

With the plug disconnected, the alternator will default to 13.8v output.
The Dominator is programmable to output PWM through simple configuration tables.

The problem was finding the plug to suit, however I eventually found the part number and eBay to the rescue so here is the details for others.

ACDelco PT2787

Mitsubishi 140 AMP Alternator

The body is off again and upside down for cleaning up and painting the underside.

TPS (Throttle Position Sensor) and IAT (Inlet Air Temp Sensors fitted and wired.

Holley Loom is plug and play.

Crank Censor, Knock Sensors, Coils, Cam sensor all wired.

Waiting on a pig tail for the LS3 EVAP Purge solonoid.
LS3 Evap Purge Solenoid Plug
Part Number is Dorman 645-631
Another elusive plug.