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"

Tuesday, November 13, 2012

Engine Mounts

The engine I have came from a 2011 wrecked HSV, so its the 317kw LS3.
The VE engine mount brackets aren't suitable as they place the engine too far forward in the CR chassis.
By swapping them left too right, they position the engine in the right fore / aft location, but using the VE bracket means the need to use the VE mounts which make the engine sit higher than intended,

The CR manual recommends VX, VY, or VZ LS1 engine mounts. However, the mounts in these earlier commodores aren't symmetrical, and push the motor out to the left hand side, requiring that the RH chassis mount be filed out to get the motor central;
However, there are alternatives which give a better fit and finish.

This pic is from another CR builder showing the engine mount chassis slot after filing out to get the engine sitting centrally.

I didnt want to do this with out investigating other options first.

 This is the VZ engine mounts, you can see the difference is about 35mm from left to right engine mount.

I bought these off eBay before I knew about the alignment issues, I also sold them on eBay just as quick, once the solution was found.

After lots of scouring the LS engine sights, i found that the VX,Y,Z commodores used a LH factory Corvette Bracket Position and a custom AU designed bracket for the RH side.

Investigating the Factory Corvette Mount Brackets I found they are symmetrical, the hole positions are exactly the same location as the LH VZ engine mount.
These are the latest version, available online through several US retailers, and from some of the local crate engine importers here.

They generally get removed and replaced for custom fitment into our local cars.
These Corvette Mount Brackets came off an LS3 Crate Engine, i bought them locally for $55 each.

The GM part numbers are:

General Progress Update

Progressing with some fiddly bits over the recent month or so,
Firstly, been playing with my CNC mini mill, I blew up the drivers because the stepper motor inductance was way too high for the "black box" that makes it all works.
This is delaying me from making some bits and pieces as i learn how to fix it.
I found a good local resource and have the bits now to put it back together except for some custom mounts which I lathed up over the weekend.
I've upgraded the steeper motors and bought new drivers and power supply so should be going again shortly.

For info, the mill is a Sieg X3 with CNC Fusion Ball Screws and Nuts, custom made mounts, Nema 34 Steeper Motors, Gecko 203V Drivers, and run from a PC using Mach 3 and Cut3d Software.

CNC Fusion now do a complete bolt up conversion kit which simplifys the change over.

On the Cobra side of things however, I finished machining up all the insulator bushes for the Brake, Canister, Fuel Line mounting brackets.
Still have the Stainless Clutch line to make up and fit to the chassis, bent up the tube to fit, but need to mount.

This is the Right Hand Chassis Rail with the Canister Vacuum Line and the Fuel Line mounted.

The Vacuum line is 1/4" Stainless, the Fuel line is 1/2" Aluminium with -8AN fittings.

The bushes are machined from Black Nylon Rod.
I wanted to do something different from the usual tube clamps and give the fitting a more custom factory look.

The LS3 and the L98, L76/7 engines have the Corvette Serpentine belt line, and on the VE Commodore, the Power steering pump is mounted up high on the passenger side (LHS).
The PS pump sits considerably further outboard than the head mounted LS1 pumps, so much that the pump hits the inner wheel well on the CR body.

This pic is from another local builders CR showing the interference of the pump to the body.

Initially I intended to fit the LS1 pump, however, the LS1's used a Firebird / Camaro belt line that sits an inch or so further forward than the Corvette, meaning  I would also have to change Alternator, Water pump, Idlers and all the associated brackets.
Key bit of note here is that there is 3 factory belt lines and several aftermarket systems, all different.
The 3 factory lines are Corvette, Camaro/Firebird (F Body), and Trucks (stick out the front even further than the rest.)
Heres some Links to interesting info:

I looked at the after market belt systems, there are many, and i would like to fit a clockwise water pump and simplified belt system, but decided i would relocate the factory pump for now, so it is now moved inboard bolted to the head in a similar method to the LS1.
The top mount uses an existing mounting position in the head, the bottom mount hole has been driled and tapped into the head, this goes through about 10mm of casting before entering the water jacket.
I'll use stainless socket head cap screws, M10x1.5, and seal as per all the other threaded bungs on the block.
(Mod - Changed to KRC power steering pump, Pulley and Mounting - see future post)

I intend to replace the reservoir tube with a -AN fitting if i can find one, otherwise, I'll make one.

I've been cleaning up the engine, I've tried just about every commercial product i could find and some home brews as well, but basically, i've come to the conclusion that to get that new cast look, there is no chemical cleaning method that does a great job, about the best so far would be a custom mix of lemon juice and water and boil the parts, impractical when you dont want to disassemble the complete motor.
The best finish i achieved was a cheapy sand blast kit and I used a couple of bags of soda.
however, short  of sanding and polishing, I've decided to paint the block and i found some VHT paint called NU-Cast Aluminium SP995.
The finish is pretty good and natural looking.

Top View, only the un-machined surfaces have been painted.

I decided to strip the deck when i discovered a wasp nest between the inlet manifold and the valley cover.

Left hand side,
The engine mount is still the VE commodore standard, not the required Corvette style mount.

In this pic you can see the original VE LH engine mount, this will be replaced with Corvette mounts.
This mount positions the block too far forward.

Carbon Fiber Rocker Covers. Trial fittment.

These covers are beautifully made and finished, using the factory head cover seals.

These are available from Scooters Performance, or, and are made by;

Oil filler and mounting bolt anodized fittings.

Aluminium internal braces, stainless tube mounts,
Groove for the OEM valve cover seal.

The left bank cover also has a breather tube and baffle, which i will probably block off and relocate hidden away on the valley cover.