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, December 11, 2014

Headers Part 1.

The space for headers, particularly the rear 2 cylinders, is very tight on clearance to the foot wells, and steering rod between the column and rack on the CR,  This necessitates a custom made header design,
Other criteria for me was to also utilize as much OE emissions controls  as possible to get me through the certification engineering and registration process.
The emissions need to meet IM240 requirements, and noise db, so my header design needs to be able to adapt from OE Catalytic converters and under-body muffled rear exit design to the 4 into 1 of the iconic cobra side pipes in the future if I want to go this way.
At the moment, I'm thinking under-body but exiting to the side behind the doors.

 A while back, I procured the Cats from another CR builder friend, they were to be discarded from the donor wreck he got his Engine and Trans, Diff and several other components from, (thanks Phil).

After figuring out if I could make them fit in the space, which entailed finding short merge collectors, and some tube routing concepts, i made up a stand to hold the cats in place while i played with different tube locations.

Firstly, I decided on 1.75" tubes, a little research suggested this was the ideal tube size for a mild almost stock LS3.
Drivability is all I'm after with this combination and 434HP in stock form in a 1000kg car will be plenty for me.

I bought some exhaust modelling blocks from "Icengineworks" via Summit in 2", 3" and 4" CLR and some straight blocks, enough to do 1 side at a time.

The blocks come in kits as well with all sorts of other bits and pieces, but I didn't need to obtain these and I'm glad I didn't buy the full kit.

After playing with the blocks, and different options of over and under the steering rod, i finally settled on the above.
This design has all the pipes over the top of the
steering rod which will make for easy removal if required.

The blocks are very quick to adjust to make fit and too maximize the use of bends with minimal cuts and welds.
In this design, the 1st 2 pipes have only 1 join each, and the 3rd has 2 joins and the rear pipe has 3 joins.

In this pic you can see the merge collector, I bought these from SPD Exhausts in the US.
Get yourself a catalogue, great bits and pieces.

The ring above it is a flange I had laser cut. Actually i had six cut, 1 each for the headers, 1 for each collector, and 1 for each of the 4 into 1 side pipe assembles.
This is so I can split the collector off the header and mount the side pipes to at a later date.

The 2 flanges will have V-band clamp rings welded to them for connecting together.

So basically, as you can see in the first pic, the blocks have alignment arrows.
Where the arrows align, the blocks are curved in 1 continuous arc plane, Where they don't align is the point of a change in the arc plane, so I marked this point with a marker pen. on the changed plane then separate at the mark and cut the component from the matching radius mandrel bent pipe.

VoilĂ  !

Here you can see the 2 bends tacked together in the same orientation as the model.

You can also see the marker pen on the join at the change in arc plane.

Eventually, you end up with this.

I have never done this before, and I'm really happy with the result.

Next step was too remove the pipes and weld the joins, before reassembling to the flanges again for final welding.

After tacking it all up, remove the header and mounted to a spare LS1 head to keep it from warping when I welded it all up.

In this pic, you can see I've flapped and filed out the MIG welds on the tubes for a smooth flowing look.

Test fitting the collector again before final welding.

Mig welded up all the flanges while clamped to the spare head.

All done except for O2 bungs and V-band clamp flange on the CAT outlet.

A view from underneath.

Next is to model up the left bank and do it all again.

Saturday, November 1, 2014

Engine Mount Spacer and Chassis Wiring

Started and completed the chassis wiring up to where it will go through the firewall.
I am going to run 3 looms in the car.
One for the parts on the Chassis such as Fans, Horns, ABS sensors, Fuel Pump, Windscreen Pump,  and some water and diff oil temp sender, and another for Engine and Transmission, and a 3rd for body mounted components like Lights, Dash Wipers etc.. etc..

I'm not intending to put ABS on the car, but put the wires in the loom as a "just in case" I ever decide too, or maybe traction control.

Also after reading about sumps protruding below the frame rails, I laid a straight edge across the rails below the sump, dead level just scrapping the sump surface, so I decided to lift the engine slightly for clearance.

10mm Spacer added under engine mount.

I cut the spacer on my mini CNC mill from some aluminium stock, then put in the tumbler overnight to smooth all the edges.

In this pic, you can see how level the sump to frame rails was.

ABS wire from the upper control arm to the sensor in the side of the knuckle.
The sensors are factory VE Commodore/
The plugs are off the shelf Narva AMP 2 pin plugs.
The clips holding the loom to the upper arms are bike cable clamps suggested by another CR builder.
These ones came from ebay in a, stainless steel, 6 pack and are 28mm diameter.

Fuel pump and float sensor is wired.
I also tested to make sure it works...all good.

Friday, September 19, 2014

LS3 Dual Quad EFI Intake Manifold

In a previous post, I was intending to fit the Holley Dual Quad LS cathedral port inlet manifold to the LS3 rectangular port heads by making up an adapter flange, however, this became unnecessary as while I was emailing Holley about some other details to do with the throttle body linkage, I learned that they were prototyping an LS3 version.
Some special arrangements via Summit Racing resulted in me obtaining one.

Holley Dual Quad LS3 EFI manifold part number 300-134

Fitted up with the original LS3 injectors.
Two different sized rail mounts are included with the kit to suit LS3/LS7 style injectors or the longer EV1 style injectors.
New replacement lower injector O-Rings are also included.

The overall manifold sits about 1/4" higher than the cathedral port version.
The fit up however wasn't plain sailing,

Here you can see the manifold doesn't fit up to the stock heads with a gap between the faces.

The overall casting was too wide to fit between the head port machined surface.

There is sufficient material on the manifold to make it fit by machining off a bit of the flange.

In this pic, you can see the edge of the flange overlaps the casting at the top of the head port face machined area.

Set up in the mill for machining.
Could easily file off each flange to fit if required.
I machined a few millimetres off each side of the flange casting.

Finished  mods.

The mounting bolts holes for manifold to head are in perfect alignment and the ports are very well matched to the stock heads.

I'll post some more pics of the injector rail to manifold mounting shortly, forgot to take pics.

Monday, August 25, 2014

Fuel Tank - Finished

Well, finished off the fuel tank installation today,
First stop was Clark Rubber for some small rubber bumpers to fit to the chassis to insulate from the tank and some Neoprene for the straps to insulate from the tank.

Some careful bending to get the straps to fit neatly and all bolted up

Friday, August 22, 2014

Tank Straps & T-Bolts, some more Progress

Here's some more pics of the straps progress.

Received the T-Bolts back from HPC coatings.
As usual, first class finish and service.

Straps held together with Stainless Steel Rivets.

Straps finished,
Ready to install.

This is as far as I got,
Need to buy some tank strap rubber insulator material, and some pads to insulate fuel tank to chassis.

Almost there.
More pics soon.

Tuesday, August 19, 2014

Tank Straps & T-Bolts - Unfinished

I like the look of T-Bolt designed strap clamps and V band clamps, Turbo clamps etc, and thought I would try to replicate this for the fuel tank straps instead of the usual hole in a strip of material bolted to the chassis.
Initially I thought I would be able to buy this type of product but after searching the web and calling several clamp manufacturers, I found only 2 that would custom make small runs of parts, Clampco in the US, and Hilton Manufacturing here in Australia. There maybe others, but I couldn't find them.
I visited Hilton, in Dandenong, they are truck tank and band manufacturers, they make T-Bolt Band Clamps but the scale is far too big for my use and their tooling cant make what I needed for my application, so that left Clampco in the USA,
I sent an email with my specs, and they advised they make this item from 1-1/4" x 60 thou strip (32mm x 1.5mm) with 3/8" (10mm) T-Bolts  to any length required, it came with a hefty US$900 price tag excluding freight.
So I decided to have a go myself.

Firstly, the T-Bolts,

First effort was a poor looking result, butt welding a 10mm bolt shank to a 10mm rod,

Second effort was much improved, 16mm rod with a 10mm hole through the middle, then a bolt with the head cut off inserted in the hole half way and welded in place from the top.
Ground off to finish the part, I made 5, 4 off to be coated, 1 to use in a forming jig I made for the straps.

This is the forming jig I made from 2 scrap pieces of angle iron, a hole between them for the T-Bolt to be pulled through.

In this pic, the strap is about to be pulled into the slot.

The straps were laser cut from 1.5mm polished stainless,

As you tighten the nut, it pulls the T-Bolt into the groove forming the strap around T-Bolt end.

This is the second jig I made from another bit of Angle Iron, a hole in it for the T-Bolt to hold the strap firm against the vertical angle, then 2 bolts through the horizontal with a bar bridged between them.
The bar is placed so it will press down just in front of the t bolt forming the strap around it to make a "P" clamp.

In the end, I stuck it in the press instead of winding the nuts down.

Pressed and formed.

Straps finished but awaiting the T-Bolts to return from coating.

After assembly the straps will be closed up and held with stainless rivets.

The rivets take no load other than holding the assembly closed.

More pics when I get them finished and on the car

Tuesday, August 5, 2014

Tail Shaft Part 2.

Fitted up the tailshaft; Length between the uni centres was 240mm when fitted, with 40mm retraction, so I can slide the flange off the spiggots and remove and drop the shaft out through the chassis if required.
The sliding shaft is a standard Spicer part, custom length built for me by GJ Drivelines in Keysborough, Melbourne and fitted with 1350 series universal joints between the Sonnax flanges.

The Sonnax flanges have 1/2" mounting holes, the diff flange has 12mm threaded bolt holes, so I drilled out the diff flange holes to 1/2" and then used 1/2" x 1" Unbrako shoulder bolts and lock nuts to fasten together.

The gearbox Tri-flange has 12mm holes in it, I tried to drill these out to 1/2" as well, but the flange material is so hard I  couldn't even scratch the surface, so I turned down the shoulder bolts to 12mm diameter. (double shoulder i.e. 1/2" through the Sonnax flange dropping to 12mm through the Tremec OE flange)
The shoulder bolts accurately align the holes like solid pins.

Sunday, June 22, 2014

Tail Shaft Part 1.

In a previous post, I detailed the changes to the diff tail shaft flange on the Holden VE Commodore diff to accommodate a Ford BA style flange and tail shaft universal coupling.
I've been avoiding the day I would have to cut the spigot shaft off the front of the pinion shaft to fit the Ford universal joint coupling.
What's more, there was a lot of effort in finding the Ford part as it is out of production, usually only available from wreckers with a diff still attached.
While researching ways to direct couple the tail shaft to the gearbox, a Tremec TR6060 with the Tri-Flange mount, I found Sonnax in the US make a part sold through The Drive Shaft Shop. Sonnax part number TL35-ALFY-01 to fit the Camaro and G8 models also fitted with TR6060 gearboxes.
After email correspondence to confirm the fit, I purchased one.

Sonnax part number TL35-ALFY-01
fitted to TR6060 gearbox.
After confirming this part, I broadcasted the find to other CR builders I'm in contact with.
One of my friends also bought one and during his fit up discovered that it was also a perfect fit for the original VE Diff flange, which if didn't interfere with the handbrake cable bracket on the chassis, would eliminate the need for the Ford flange conversion and the removal of the spigot shaft on the pinion.

The flange confirmed fit on the original diff Tri-Flange, but interferes with the Hand Brake Cable Bracket welded on the chassis.

Another shot showing the interference.

After measuring up the available cable space, I made a bracket narrowing the distance between the cables, and moving the bracket a few millimetres to create about 10mm clearance to the flange.

Quicker than saying
"Lets Think About This For A Moment"
I cut it off and located the new Hand Brake Bracket.

Bolted in place after confirming location.

Now with plenty of clearance I have ordered another flange, ended up with a standard diff set up with out modifications, standardized the flanges and universal joints to 1350 type bearings.

Next step is to get a sliding tail shaft made up and balanced to fit between the 2 flanges with enough compression to be able to remove down through the chassis if needed.

Power Steering Pump Mount

I eventually relented on the woes of getting a factory Power Steering Pump to sit where I wanted to mount it when I discovered a pic on the web of a CT525 engine from Circle Track with a belt layout exactly as I wanted it.
After looking around there site, with no indication to what was fitted to the engine, I came across a customers car on an LS forum with decent res pictures and zooming in revealed the name and part numbers on the pulley.
An email to them soon had a list of brackets, pump and pulley part numbers to suit the LS3 Corvette belt line.

The bracket mounted to the head.
part number # 71410040

Installed with a new Gates Micro -V 6PK2020 Belt.
Part number #  K060795.

Power Steering PUMP is KRC #63200000
Pulley is 6.5" KRC # 20020650,
They also do a smaller 6" pulley # 2002600