Engine Bay Cooling

Some kit cars have bonnet scoops, some have louvers, some even have NACA ducts, but the Avon has no openings as standard.  For most of the year this is not a problem, but I had noticed that during the summer months, there can be quite a big heat build up and the top of the bonnet is very warm to the touch.

So I weighed up a few options, including fitting ready made grilles, but in the end I decided upon some simple holes.  I used hole saws in the cordless drill with the torque turned right down.  Then, once the  holes were done, I glued black mesh to the inside of the bonnet with Grip-Fill.  I'd previously had success using this on the inside of the GRP bodywork to affix things, such as cable tie mounts.

Here are the four holes that allow escape of some of the heat from the exhaust headers:

And here are the two larger holes centered on the midpoint between the two K&N filters.  As well as allowing cooler fresh air in to the engine, they also allow out of the engine bay that little extra induction noise!

Overall, a simple modification.  The engine bay definitely runs a little cooler and in my opinion its added some additional aesthetic interest.

Alternator Upper Bracket

Whilst on the return from a Southern Kit Cars trip to Bletchley Park, I thought I could hear a metallic rattling when the car was idling at junctions.  When it was safe to do so, I pulled up at the side of the road and took off the bonnet.  I discovered that the upper alternator bracket had failed.

Thankfully, the new bottom bracket is very robust and bolted up very tight.  This single bolt was holding the tension in the alternator belt.  Aside from worries about the alternator not charging, I was concerned that if the belt started to slip, then the water pump might not function correctly, with the engine potentially overheating.  For the rest of the return trip I kept to a steady speed on the main roads.  I made it back home, where I was able to look at the bracket failure in more detail.  It can be seen where the failure started, from the outside rusty edges and then it has spread across the middle, to completely separate.

For a replacement, I fabricated a new bracket out of a single thick piece of L-section mild steel.  It is a little overkill, but I really don't want to have any more alternator bracket issues.  Even if I'm carry just that little bit more weight than is necessary.  In the future I may trim off some more of the excess metal.

Engine Mount Strengthening

The offside engine mounting plate is fixed to the chassis spanning two chassis rails, where they come together in a vee shape.  This is strong enough to take the loads transmitted from the engine.  On the nearside however, it is a very different story.  The flat plate is welded on top of just one chassis rail.  Over time the loads from the engine cause this to droop and eventually this puts an abnormal loading on the engine mount itself, which then fails.

I'd kept an eye on my nearside mounting plate over the months and it had always been fine.  Recently though, I noticed that the non-welded side had drooped around 10mm.  It was on its way to causing the engine mount to fail.

So, I fabricated two triangular fillets from 6mm mild steel and got a local garage to weld these in place, after 'jacking' the plate back into its original horizontal position.  The welds are not the neatest in the world, but they seem to be good enough to be strong.

Denso Alternator

I'd been having some more issues with my Lucas alternator, so I took it apart and ordered a service kit, which included bushes, bearings, rectifier and regulator.  I started to overhaul the alternator, but during the process I decided that I was not really happy with the situation.  I wasn't convinced that I would not have further problems in the future, so I finally took the plunge and ordered a genuine Denso alternator.

The new alternator is rated at 40 amps, so should be more than sufficient for the modest electrical loads that my Avon can generate.  It weights about 2kg versus the 3kg of the Lucas, so there is a nice weight saving too.

When I removed the Lucas alternator I discovered that the lower mounting bracket had failed.  The front lug had snapped off and it was just the rear lug that was holding the alternator on.  It was lucky that I discovered this in the garage and not at the side of the road!

I took the old lower bracket to the local fabricator/welders.  They removed the old lugs and added strong new fixings for the Denso.

For the alternator tensioner I re-used the old upper bracket and connected it to the alternator with two rod ends and some 8mm threaded rod.

The main output connection is a threaded copper post.  I had a proper battery cable made up that had the correct size ring connector for the alternator on one end and the correct size at the other to connect to the starter motor connection (where the car's main loom terminates the +12v).  This arrange should be much better than the Lucas spade connections, which are prone to arcing.  The cable is more heavy duty than the original Tiger alternator output wire, so this can only help.

Oil Catch Tank

I'd been meaning to fit an oil catch for a while.  Then a new OBP one came up on eBay locally and the price was absolute bargain.  A guy had bought it for his Lancia Statos build, but had changed his mind; he no longer wanted a 1 litre tank and was going to use a 2 litre tank instead.

Mounting the tank was relatively straight forward, but before the pipe from the crankcase could be connected, the internals needed to be removed from the Positive Crankcase Ventilation (PCV) valve.

The valve itself just pulls out of the rubber bung in the crankcase.  To get the internal of the valve out I ran the angle grinder around the end using a very thin metal cutting disk, 0.8mm I think.

The internals were then discarded and the valve reinserted into the rubber bung in the crankcase.

Here is the catch tank with the crankcase and camshafter cover pipes plumbed in.

Then finally an air filter was added to the top side exit.

CKC/Omex Llandow Track Day 2013

On the 18th May I attended the CKC/Omex Track Day at the Llandow Circuit in Wales.  The trip started when I set off on the Friday afternoon, with the passenger seat fully loaded for a night's camping.  I took the cross country route out west, along the A4.  There were a few good sections of road, but on the whole it was disappointing and very slow, in a large part due to school run traffic and people heading off early for the weekend.  I'll know next time.

To break the journey I stopped at the Castle Combe Circuit and took a quick look around:

Then onward to the overnight stop at Llandow Caravan Park.  This is literally the other side of the fence from Llandow Circuit - good for an overnight before and/or after a track day, maybe not so good for a quiet getaway!  There were some others staying at the site whom were attending the track day the next day, so there was some like-minded company.

The weather the week before had been pretty wet and I nearly cancelled the trip.  However, I'm glad I didn't as I woke to a sunny dawn, with clear blue skies.  A stiff breeze coming from the sea to the south, but that didn't matter.  The gamble had paid off.

After breakfast those drivers staying at the camp site drove the very short distance to the circuit next door.  Beats a long motorway drive any day.  After the usual safety briefing and admin formalities we were out on the track.

Llandow is not a big circuit, but it certainly has enough to keep you entertained: a couple of long straights, fast bends, chicanes and a bus stop just after the pit exit.  The circuit is quite taxing on brakes, particularly the deceleration at the end of the main straight into the bus stop.  Here you are slowing from 100+ mph to around 30 mph in a very short distance.  Then with a short lap before the next big deceleration there is little time for the brakes to cool, at least on a set up such as mine with solid disks up front.  There was a noticeable degradation in braking ability after five or six laps.  This coincided nicely with rest stops anyway.

The majority of the other cars there were of higher spec: more highly tuned engines and semi or full slicks.  There did not seem too much difference on the straights, but I did fail to keep up on the bends.  My Toyo T1-Rs will be replaced next time with something a bit more grippy.  Maybe not R888's, but at least R1-Rs.

Here are some of the free pictures that were included in the entry fee:

I had a really enjoyable day and learnt some more about the car's handling and hopefully improved my technique as well.  I will definitely try to make the event in 2014.  Fingers crossed for another dry, bright day.

As I wanted to get home as quickly as possible I used the M4 for the return route.  I stopped at the services next to the old Severn bridge for fuel.  When leaving there is a short downhill section to a roundabout.  It was here, under heavy braking, that I noticed the brakes fade quite a bit.  For the rest of the trip I took it very carefully.  I think, whilst on circuit, the heat generated in the front calipers may have boiled the brake fluid.  I had standard DOT4 fluid in there.  The week after the trip I replaced it with the much higher spec DOT5.1 fluid.  I've had no problems since, but it would be interesting to see if this fluid could withstand the rigors of a full track day.

More Alternator Woes

Prior to my recent trip to France I noticed that the low battery light was coming on.  On my Acewell dash this is set to come on at 12.5 volts and off again at 13.0 volts.  The alternator warning light extinguished normally after starting so there was no issue with the excitement of the field, there was another cause.

I ordered a replacement set of brushes for my Lucas ACR alternator just in case they were worn.  When I took the back off the alternator and dismantled the brush box I discovered that the wire attaching one of the brushes to the terminal had broken.  I think that the current was being carried by the spring alone, hence the erratic charging of the battery.

Replacement of the brushes is a fairly straightforward task.  I also did a quick health check of the nine diodes with the multimeter.  Then a quick test drive proved that the full 14.2 volts had been restored.  Then it was off to France for the weekend.  All was okay until after arriving in France I noticed the low battery light was illuminated again.  Oh no.  Anyway, long story short I managed to nurse the battery through the weekend and I made it back to the UK without the need for a breakdown truck - phew!

So, alternator out again, back off and then I discovered this:

The red wire had snapped off from its ring terminal.  I suspect that I had trapped the wire when previously replacing the back cover of the alternator.  I soldered a new ring terminal on and carefully refitted the back cover.  Testing proved that the full 14.2 volts had been restored.  Hopefully, there are no more alternator problems.

Rallye des Jonquilles 2013

The 14th April saw us take part in our third road book rallye in Northern France.  Here are a few pictures.

Driving along the northern French coast on the Saturday.

Our first visit to Belgium in the Tiger was for a lunch stop, just over the border in Diksmuide.

Diksmuide is a pleasant town with parking on the square and restaurants and cafes conveniently located around the edge.

After lunch we visited the local trenches from World War 2.  They are really well preserved.  Very sobering to visit and imagine what life must have been like at that time.

The rallye itself was on the Sunday.  Around 150 cars queuing for the start line.

The mid-morning stop for coffee was at a local golf club.

As always a very nice three course meal was served before the final stage of the day.

Ready to depart after lunch.

A beautiful afternoon, ready to start the journey home.  Happy days!

Car Limits Day at North Weald

Yesterday I went to the Car Limits day at North Weald airfield.  There were a few of us from the Southern Kit Car Club, with 25 cars in total attending the day.  These ranged from a Ferrari 360 to a Ford Escort Estate!

The weather wasn't very kind on the way there and back, but wet tarmac made the session that bit more interesting.  I learnt a lot about handling car, which could never have done on the public highways.

Here is a short video of a couple of the circuits:

Mud Flaps

Often when out on a run down country lanes I find that I end up having to drive the car through puddles or being caught in a heavy rain shower.  With the positioning of the front cycle wings there is quite a bit of space for the water to spray up towards the side of the car, the occupants and even the interior of the car.  It was time to do something about it.

I bought 3mm thickness rally car mud flap material.  There was 4mm available, but I thought that would be too heavy.  Fortunately one piece of material cut in two was the perfect size for each side of the car.  A couple of 4.8mm rivets were used on each mud flap to hold them in place.  I positioned the mud flaps about 65mm above the ground so as to prevent them being caught under the wheel when reversing up a bump.  This could tear the cycle wing off the car.

I've been out for a test drive, up to motorway speed.  The mud flaps seem quite stable and didn't fly off!  I now just need to find out if they actually stop the spray of water from the road.

Raceline Wet Sump

I have never been entirely happy with my sump installation.  In particular, the fact that there is no baffling, with the consequent risk of oil surge when driving hard.  When building the car I had changed the standard Zetec oil pressure switch for a lower (15psi) version.  This at least should give some advance warning of oil pressure problems, but by the time it illuminates permanent damage to the engine may already have occurred.

In 2012 I did have one trip to Brands Hatch and one to Curborough Sprint Circuit.  While I had no oil pressure issues on these two occasions I started to think that I'd be pushing my luck with the three track sessions that I have booked this Spring.

So I decided to bite the bullet and upgrade to the Raceline wet sump.  This is very highly rated by those that use it.  It is even used on many race cars.  Most racers considering it to be good enough that at upgrade to a full dry sump installation is not even necessary.

The old sump was removed without any major problems.  Then it was time to start preparing the Raceline sump ready for installation.

Here is the main pan.  It is a very nice piece of engineering and you can see where the effort has been spent on the design, the casting and the machining.

Here is the Ford windage tray, Raceline windage tray and oil pick up pipe, etc.

First the oil pick up pipe is installed, with two rubber o-rings to make a seal into the main pan.  A metal filter gauze is inserted into this pipe from the outside of the sump.  This can be removed and cleaned at oil changes, if required.

Next the Raceline windage tray is bolted into place.  This windage tray is one of the methods used to control oil surge.

After that the Ford windage tray is bolted to the Raceline windage tray.  The Ford windage tray is designed to 'scrape' oil of the crank and con-rods.  Helping the oil to fall to the bottom of the sump and not be whipped up into the main engine block.

Standard Zetec Silvertop sump gasket fitted along with oil drain plug and gauze filter plug.  There is a double top hat spacer with rubber o-rings fitted that makes the oil seal between the sump pan and the engine oil pump.

The sump itself fits very well.  The main issue, and one which consumed a lot of time, was getting access to all the sump bolts.  Many are hidden by things like the starter motor, engine mounts, etc.

The old Tiger ERA sump was higher than the gearbox bellhousing.  The Raceline sump is level with the bellhousing.  The previous sump had around 100mm of ground clearance, but unfortutately the Raceline sump only has about 65mm.  This is too little, especially as the car is used a lot on country lanes, where there is often a raised centre to the road.  So the springs on the front dampers were wound up by 20mm.  Due to the geometry of the wishbones this translates to an increase in ride height of about 35mm, i.e. back to around  100mm under the sump.  Result.  I will take a look at the rear ride height as soon as I can and get the car leveled again.

Before running the engine for the first time I removed the plugs and rotated the engine by hand (socket set on crankshaft pulley).  I wanted to make sure that the Ford windage tray was not fouling the crankshaft or con-rods.  Next, I took the spark plugs out and cranked over the engine until the oil pressure light went out.  Once this was done it was time to fire up the engine and go for a test drive.  I'm happy to report that so far all appears to be working fine and there are no leaks.  Roll on the good weather and some track time!

Cooling System Updated (Again!)

1. As advised by Tiger I originally ran the car with no thermostat and no bypass plumbing.  I understand this is a fairly standard set up for race cars.  However, if quickly became apparent that the engine was being over cooled.
2. My next configuration had a thermostat with a 3mm hole in it as a bypass.  This worked very well all summer - the engine stayed at a constant 88oC, unless the fan needed to cut in.
3. Once the cold mornings of autumn arrived the engine started to run cool again.  Things were fine at lower speeds, but once there was a significant air flow through the radiator the coolant temperature struggled to maintain 80+ oC.  So I decided to introduce a full bypass pipe and fit a thermostat with no bypass hole.  To do this I had to fit a thermostat housing from an earlier Silvertop Zetec.  This was necessary in order to fit the coolant temperature sensor in a place where it would get a reading prior to the thermostat opening (as the Blacktop Zetec housing has no sensor holes and I'd previously had the coolant sensor in the main pipe to the radiator).  This set up generally worked very well, but there was one problem: somehow air from the expansion tank would make its way to the top of the radiator, which is higher than the pipe that feeds it from the thermostat housing.  A little bit of air would get trapped there each time the engine was run until there was sufficient air there for the flow of coolant to break down - not good.
4. So one more modification and hopefully the final configuration.  A 8mm hose barb was welded on to the top of the radiator and plumbed into the pipe joining the thermostat housing to the expansion tank. Now all works well.  Any air can return to the top of the system and an added bonus is that the hole coolant system is now self bleeding, which will help when I come to renew the coolant at future services.

Here is a schematic of my final cooling configuration:

8mm hose barb welded in to the top of the radiator.  It is just above parallel with the ground.  This is to allow it and the pipe to fit under the curvature of the nosecone.

Full routing of the new pipework (apologies for the poor quality mobile phone pictures, must use the proper camera next time).

C-shaped brackets were fabricated from aluminium strip.  These were fixed under the camshaft cover bolts and rubber lined p-clips were riveted to them.