Stag Rescue: Part 20
Mike continues preparing the outer panels for colour coats, and also paints the Stag’s underbonnet area.
Mike continues preparing the outer panels for colour coats, and also paints the Stag’s underbonnet area.
Just to recap, I am painting the shell in an acrylic lacquer, rather than more modern two-pack paints – the major reason being health and safety, as the acrylic lacquer doesn’t contain the isocyanates that can result in health problems if not used with the correct equipment. I also have prior experience in painting cars in acrylic lacquer and, while it does not deliver the durable finish of a two pack system, I have found that – with care and time taken in the final buffing stages – an excellent finish can still be achieved, which will not prematurely deteriorate.
The shell had previously been primed and then given a single coat of spray putty, so my first task was to sand all panels with 240 grade paper, which was selected as it is allows fast removal of the high spots. Where appropriate I used a pneumatic random orbital sander to speed up the process, but with all the curves and edges on the Stag, the majority of the sanding was performed by hand using a variety of sanding blocks of different shapes and densities. Dry sanding was used using ‘non-clog’ paper (obviously named by someone with a sense of humour) that produces dust, so it was important to wear an appropriate dust mask and use a vacuum cleaner to remove the dust from the workshop. The colour variation between primer and spray putty is very useful for helping judge and reveal high and low spots during the sanding operation, while the sanding invariably exposes many previously undetected minor imperfections that require rectification, often with an application of blade putty. In some cases my over enthusiasm sanded through the putty and primer down to base metal, so
these and the sanded blade putty were spot primed in preparation for spray putty. After drying overnight, the spray putty was sanded in a similar method to the first coat – as further primer is to be applied, it isn’t necessary to obtain a fine sanded finish on the putty. The sanded second coat of putty resulted in a much improved overall result, although I was concerned with the profile of both rear wings where the swage line blends into the wheel arch. The decision was made to apply primer and then review, so two coats of grey primer were applied, leaving time to flash off between coats and then left to dry overnight, which did nothing to overcome my concern on the rear wing profile, so I decided to move on to finishing the engine bay and come back to the rear wings later.
Bay of plenty
The engine bay primer was dry sanded with 320 grade paper, prior to final wet sanding with 400 grade that produced a good surface for the first of the colour coats. Two colour coats were sprayed on, allowing a few minutes to flash off between, then after about forty-five minutes another two coats were applied and left to dry overnight. Getting good even coverage in the engine bay was problematic, in particular the corners behind the inner wheel arches, where the spray mist was blowing back and giving an appearance of overspray to the adjacent sections. The following morning the paint was wet sanded with 800 grade paper to remove the spray drift and another two colour coats applied. I was
using a combination of two guns – my standard HVLP and the small touch-up gun, then experimenting with pressures, fan width and paint flow rates. In the end I concluded that the best coverage in the corners was achieved with the HVLP set on very low air pressure, low paint feed and minimal fan width, as this reduced the volume of spray blowing back out of the corners. The gun then required adjustment to spray the larger under bonnet areas. The problem with the touch-up gun was that it is a high pressure unit and, even when set on the lowest pressure to obtain paint atomisation, it was producing more blow back than the HVLP. The result, although reasonable, was far from perfect and I spotted a small run on the rear bulkhead that required rectification, even though it would be hidden by the insulation pad. The paint was left for a few days to thoroughly harden prior to rectifying the paint run and re-coating.
In the meantime, buddy Ross had called in for morning tea in his Stag and I had a chance to examine the rear wing profile on his car, which convinced me that I should undertake some reshaping on both my rear wings. So it was out with the sanding blocks and 120 grade dry sanding paper for a slight change to the profile. The area in question is adjacent to where the Rimmers repair panel is welded to the original wing and had been coated in a very thin skim of filler to hide the welded join. After some careful sanding that cut through the putty, primer and into the filler, I was much happier with the end result, so it was primed, coated with spray putty and sanded, before two additional primer coats. Both rear wings were treated in similar fashion.
I realised that it will be easier to paint the front headlight panel prior to engine installation, so the grill and light recesses were masked, before using 400 grade dry rub to sand the panels around the lights and the front valance. The area was then washed with grease and wax remover and dried prior to painting. Six coats of paint were applied; the first was sprayed reasonably dry and allowed to flash off for ten or fifteen minutes prior to applying a full wet coat and leaving for an hour or so to dry, when two further wet coats were applied, leaving time to flash off between. After drying overnight, the area was lightly wet sanded with 800 grade paper, washed, dried and inspected, prior to applying the final two wet coats, with time to flash off between. I painted past the seam of the front valance onto the lower section of the front wings, however when painting the front wings this area will be repainted up to the front valance seam, which will provide a good joining point.
At the same time as painting the front valance, the rear side of the A-posts where the door hinges fix were given their final coats of paint. The plan here is to complete the painting on the internals of the doors, then finish paint preparation on the outer skins prior to refitting them, to ensure the changes I made to the rear wing swage lines align with doors. The door hinges will be adjusted and permanently bolted to the A-post, so that refitting doors after the external skins are finished will be easier, with less likelihood of damage.
Back to the engine bay next, where the paint run was removed by wet sanding with 400 grade wet and dry, before wet sanding the complete bay with 800 grade paper. After washing and drying, the final two colour coats were applied with the HVLP gun using the earlier settings, resulting in much improved finish that will be left to harden for a week, before a buff prior to fitting the rear insulation pad and engine.
The primer on the outer skins on the two doors was degreased and given two further primer coats, before being lightly sanded and coated with spray putty. When dry the putty was sanded – because of the panel length, the longboard was used for sanding, as smaller blocks
Six coats of paint were applied; the first was sprayed reasonably dry and allowed to
flash off for ten or fifteen minutes
can develop ripples. I was shocked at the result from this sanding, as it highlighted some high and low areas and I’d thought I’d already produced flat panels with earlier longboard sanding. A further coat of putty was applied and sanded with the longboard, resulting in a much improved outcome, so two further primer coats were applied over the sanded putty. The doors were then turned and the central area that had earlier been given three or four coats of colour was masked. The door edges were degreased, sprayed with two coats of primer and lightly sanded, coated with spray putty, which was left to dry prior to sanding. I contemplated on how to finish these areas, as most of the door bottoms had been replaced and the welds linished, with no filler to hide the join, resulting in a slightly rippled finish, but as this is not seen I decided to leave as is. I also wondered whether I should fill the factory produced spot weld dimples that are visible on the front and rear door edges. In the end I chose to continue with the factory method and allow the dimples to stay. Therefore the primer on the door edges was dry sanded with 400 grade and six coats of colour applied, giving a light sand between the third and fourth coats.
Doors go on
When all the paint was well and truly dry, the door hinges were loosely bolted to the A-posts and the first door was slid onto the hinges. The fiddly hinge to door bolts were fitted – when working on your own it is much easier if the door rear edge is supported on blocks, or in my case, an adjustable height trolley. When the door position appeared correct, one bolt on each hinge section was nipped up and the door carefully shut to check fit, then the long process of adjustments began. At this stage I was only interested in getting the hinges correctly positioned on the A-post, as this fitting will see them bolted into their permanent position. It takes many minor adjustments to first get the height correct and then the alignment with the front wing. Once correct, the door to hinge bolts can be
adjusted to get the gaps front and rear right, as well as along the length of the sill. Once door fit is satisfactory, the swage line along the car can be checked. The driver side was fine, but the passenger side required minor modifications. A few minutes with 120 grade sandpaper on a rubbing block corrected the swage line. It only takes removal of a minimal amount of paint to change the line, and I only sanded into the putty coat to get the correct alignment, but it will still require another two coats of primer.
The engine mountings required cleaning and painting, but rather than completing them on their own, a selection of soon to be required components was collected and sent off to be sand blasted and primed. These
A few minutes with 120 grade sandpaper on a rubbing block corrected
the swage lines on the rear wings
included the two engine and gearbox mountings, front disc shields, rear brake back plates, front suspension arms, rack mountings, rear suspension brackets and exhaust manifolds. The manifolds could not be primed due to their operating temperatures, so I collected them within minutes of being blasted and immediately sprayed them using a spray can of high temperature manifold paint. This paint needs to be subjected to a high temperature to fully cure, however, so I exposed the manifolds to several days in the sun where they reached over 50 C, resulting in a reasonable cure for the paint. I did consider having the manifolds ceramic coated, but the process is quite expensive and I have found that the paint lasts extremely well, as long as it is applied quickly after cleaning and before any surface oxidisation occurs. The other blasted and primed components were sprayed with two coats of black gloss epoxy enamel from a spray can and, as this paint takes time to fully cure, the items were left to dry for several days.
I had earlier unearthed the four water transfer ports and had been regularly applying penetrating oil to the threads for the temperature sender and hose fitting over a period of at least four weeks. Both temperature senders were now easily removed, probably because the sender body is brass. However, the two steel hose fittings were not as simple and required application of heat to get things moving. This resulted in slight thread damage on one port, but the other will be fine, especially after a tap is run down the thread. I am changing some of the Stag instruments, namely fitting a new water temperature gauge
reading in degrees and replacing the clock with a combined oil pressure and temperature gauge, both being mechanical. I have already inserted a boss in the sump for the oil temperature sender, but need to machine the RH water transfer port to 3/ 8” BSP for the temperature gauge sender. Also, another local owner who fitted a similar Scorcher distributor had advised that the advance/retard diaphragm interfered with the water hose connection on the LH transfer port. I decided to drill and tap both sides of the RH transfer port out to 3/ 8” BSP, so that I had plenty of alternatives for the hose tail and sender positioning when the engine is in place. The unused ports can then be plugged or used for an air bleed. I bolted a face plate to the mill table and made use of this setup to clamp the RH water transfer port when drilling for the 3/ 8” BSP ports. After drilling, a tap replaced the drill and the thread was started so that it was square with the hole. The transfer port was later clamped in a vice so the thread could be completed by hand.
An electric fan will be mounted in front of the radiator, with no engine driven fan fitted, so the front pulley that drives the power steering pump was mounted in the lathe and the fan locating spigot machined off, leaving a flat face for seating a new, shorter 5/ 8” UNF bolt. This will have the advantage of generating additional clearance between the head of this bolt and the thicker radiator.
As the engine needs to be positioned vertically to lower into the engine bay it must be lifted from the front of both cylinder heads, meaning lifting brackets were required. The workshop manual indicates that the power steering pump bracket should be refitted, as this has a lifting lug, plus there should be a lug fitted to the LH head. In my case this bracket was missing, having been removed to allow the air con bracket to be fitted. I decided to make a lifting lug for each head, as I did not like the idea of having the power steering bracket protruding from the engine when fitting. Each head has two 5/16” and one 3/ 8” UNC thread that can be used for lifting, so a cardboard template was made of the hole position and a plasma cutter used to cut two triangles from 3/ 8” plate. A section of angle was cut, drilled with a large hole for a lifting eye bolt and then welded to the plate; after three holes were drilled in the plate for attachment to the head, I had two very much over-engineered lifting lugs.
For the concave shapes, a softer teardrop shaped block was required. The car looked spectacular after the second putty coat, but further sanding will no doubt reveal more issues that require attention. After sanding the putty the few remaining blemishes were corrected and two wet coats of primer were applied, ready for final sand.
Hand sanding was required over most of the shell – here using a flat block – although blocks of various shapes and flexibility were required with all the curves and edges found on a Stag shell.
Where feasible, a power sander was used to sand the spray putty, taking care to keep sander moving to avoid producing flat spots.
The panels above the radiator and in front of the screen were sprayed at the same time.
Six coats of Carmine red paint were applied to the engine bay in preparation for fitting the engine.
The application of two coats of primer readied the area for final paint preparation.
Although the overall result was reasonable, I wasn’t happy with a small run on the rear bulkhead, or some of the spray drift caused by bounce back when spraying in the corners.
When happy with the changes, the area was primed and given a single coat of spray putty, to assist with blending in.
The spray putty was sanded, making sure the edges were feathered into the primer.
The panels above the radiator and in front of the screen were all sprayed at the same time.
After due consideration, it was decided to make a small adjustment to both rear wing profiles.
Six coats of top coat were applied. A run can be spotted on the lower wing, which will be attended to when the wing is painted. The door skins were primed and sprayed with putty.
The grille and light apertures were masked with brown paper, prior to applying four coats of primer to front valance. Additional coats of primer were applied rather than putty, then sanded prior to application of top coats.
A longboard was used to sand the putty and reduce the possibilities of a small sanding block leaving ripples in the finish.
After a further application of putty, sanding with the longboard resulted in a flatter finish, so two coats of primer were applied.
The result of the longboard sanding amazed me. I thought I had flat panels prior to sanding, but these high spots were revealed.
After sanding and removal of a small paint run, the engine bay was repainted, with improved results.
The rear of the A-posts were finished and painted, so that the door hinges could be attached and adjusted to their final position.
After the primer was fine sanded, six coats of colour were applied. On the LH side the door fit is fine, but the swage line requires some minor adjustment.
The door fit and swage line are fine on drivers side. Engine mounts, brake and suspension components, after they have been treated to two coats of gloss black epoxy enamel.
Doors were turned over and previously colour coated centre panel was masked with brown paper, so primer could be applied around edges.
After consideration, I didn’t fill the spot weld dimples on the doors, but left them to visible, as would have been the case out of the factory.
The exhaust manifolds ready for painting, after having been sand blasted.
A few minutes with the sanding block had a much improved swage line.
The hinges were loosely fitted to the A-post, in preparation for door fitting.
Manifolds after the application of two coats of high temperature manifold paint.
The four water transfer manifolds, after soaking in penetrating oil and having been degreased. Drilling the RH transfer port prior to tapping 3/8” BSP. Machining the spigot used to locate the engine driven fan from the front of the pulley used to drive power steering.
Bespoke brackets were fabricated for lifting the engine during installation.