GD427 MK IV

GD427 MK IV
One of my first drives out - 8th September 2025 (St Ninian's Isle - Shetland)

Thursday, 11 January 2018

Gearbox Oil

Before fitting the body, I thought it would be a good idea to fill up the gearbox with oil.  I bought some Dexron III rated oil as stated on the gearbox.

It took 3.5 litres to fill up to the plug level.

I used a Sealey transmission oil filling system which worked really well and didn't create a mess.

Another job done!





Cylinder Head Steam Vents

There are a lot of theories regarding the steam vent system of the LS engines, and whether to leave the rear 2 blocked off or not.  The theory is that air pockets form in the top of the head and can create hot spots.  I think it depends on how level your engine is whether you should have them open or not....

I decided to play safe and buy a steam vent kit from the USA which links all 4 vents back to the header tank.  I had to relocate the N/S lambda sensor connector bracket that I placed over one of the ports.  I just made a new stainless steel bracket to mount it and bolted it to the block with a short M10 cap screw.

This also meant that I had to drill out the small plug that blocks off the port on the rear of both cylinder heads.  I used a 3mm drill bit with lots of grease and a hoover to slowly drill out the plug.  Once I was down a little bit, I tapped the hole out to put in a M4 bolt.  This then allowed me to plug out the plug without causing too much mess!

I gave the water jacket a good hoover, to ensure no swarf had entered in.

I plugged the holes with paper towel temporarily to prevent any further entry of bits.  I will provide an update once I have fitted the steam vent kit.


Roll Hoops Test Fit to Chassis

I thought I had better try and see if the roll hoops fitted before fitting the body and finding out they require tweaking!

These fitted with no problem.  These use a stud in the outermost holes (Above the shock absorbers) and bolts in the others.  These are 1/2" UNF.

I made up a cardboard template to enable me to mark out the holes in the boot floor once the body is fitted.  This will be used later!




Fuel Rail Hose Supports

Since the IVA requires all hoses or wires to have fixings at a minimum of 300mm, I had to create some more mounts for the hydraulic clutch hoses & fuel hoses, especially around the fuel rails.

I fabricated some twisted stainless brackets to fit underneath the transmission tunnel, and some small brackets to fix the fuel hose to the fuel rails.  I drilled and tapped holes for M5 button head set screws and used stainless P-Clips.

I cable tied some of the gearbox wiring to the fuel hose supports since I thought this would be adequate.

I then re-affixed the transmission tunnel cover once this was all done.









Master Cylinder Tubing

Since the pedal box was fitted, I decided to install the 3/16" pipes that go from the master cylinders to the bulkhead connectors.  Stainless flexible hoses then go from the bulkhead connectors on the inner wing to the connector block at the rear of the engine.

I used the same copper-nickel pipe as the brake lines, and used stainless fittings.  The pipes were bent into shape and I just need some clips to hold them in place.



Fuel Filter

I got around to fitting the Aeromotive fuel filter.  This is located downstream of the fuel pumps, and has a filter mesh size of 10 micron.  I welded two stainless steel hose clamps (superclamp style) to a length of stainless flat bar to hold the filter in place behind the differential. 

I thought about putting the filter in the boot, however I want to try and ensure the boot is petrol fume free which it wouldn't be when changing it!

It is accessible from below.  I drilled and tapped M5 threads into the chassis to hold the flat bar in place.

I then cut the fuel supply line to length, made up the fuel fitting and fixed the hose with a stainless P-Clip.  I also made up the filter inlet fitting (180°) ready for when I get the bulkhead fitting going into the boot.



Windscreen Escutcheons

I formed the windscreen escutcheons in the vice using a plastic hammer, and also used a rounded piece of wood to try to form a neat curve to match the bodyshell profile.  The body curves in many ways, so it took a little bit of fettling to get it to look neat.

I then finally polished the escutcheon edges and M4 button head set screws on the polisher before fitting.

I added some extra sealant around the plate prior to fitting, and then cleaned off the excess.  I will polish the escutcheons and surrounding areas once the sealant has cured.