Fuel's Gold

After upgrading the carburettor, exhaust and air filter the car initially went well. I had plans to have it properly set up on a rolling road to really get the best out of it but unfortunately it developed a peculiar stalling issue. The car would perform well under heavy throttle application and light throttle application but would really struggle in between the two. So much so that going along at a constant pace was impossible as the car would stall and then pick up again quite violently as the power dipped and then returned. 

Further investigation under various load levels revealed that the problem was intermittent - intermittent but happening most of the time as opposed to intermittent and happening only occasionally. This ruled out anything as rigid as ignition timing. The most obvious solution was fuel supply. Given that the newly installed carburettor was believed to be in good working order the fuel pump seemed like the next logical component to look at. 

The fuel pump on the Mini is driven by the camshaft and works by moving a small diaphragm up and down to pull fuel from the fuel tank and provide enough fuel for the carburettor to feed the engine. In short, it turned out that the fuel pump on my car had been replaced at some stage in the past - not uncommon, it is 20 years old after all. However, it had been replaced with the wrong pump. An aftermarket alternative designed for the 998cc model. The 1275cc engine originally came with the larger fuel pump. The aftermarket, smaller, cheaper pump is capable of providing just enough fuel for the hif38 to power the 1275cc engine but when I upgraded the carburettor size it demanded too much.

So it was time for a shiny new part! 

At around £50 the proper SU fuel pump wasn't the cheapest way to rectify the problem. I could have installed an electric pump for about £35. For simplicity of installation it's hard to argue with the mechanical option though.

The new part on the left is quite a bit bigger than the old one, which was quite reassuring when I compared the two side by side.

 Before I had realised the fuel pump was the issue I'd tried adjusting the mixture screw to no avail. It didn't solve the problem because technically there was nothing wrong with the mixture. The SU carb allows you to set the mixture at idle and then the profile of the needle within the carburettor takes care of the air/fuel ratio further up the rev range. The small capacity fuel pump seemed to perform fine when the car was idling. It gave a false impression of the fuelling overall though so a correct adjustment would have been hard to achieve. With the new fuel pump installed and a tweak to the mixture the car ran right again!

Now it's MOT time again. That came around quickly..

Time for a new clutch

The clutch on this car had been contaminated by the oil leaking from the oil seal on the primary gear. There's a post about that here. At the time I didn't change the clutch plate. I'd hoped the clutch slip would be over soon as I'd stopped the oil leak.. no such luck! As it turned out the damage had already been done. So my Saturday afternoon task (a mere three months after my last post - oops) was a clutch change!

The trouble with changing the clutch isn't the clutch itself - it's all the other bits of machinery and whatnot in the way that have to be removed first. And as charming as the Mini is, the engine bay isn't exactly spacious. Bruised knuckles, fatigued finger tips and grime-covered forearms are pretty much guaranteed every time there's a job to do in the under the bonnet. But.. a little while later and after a few expletives the clutch and flywheel assembly was out.

Even though having the clutch and flywheel assembly out again made me think deeply about the beauty of hindsight, it did allow me to check the oil seal work I'd done. Every cloud has a silver lining.. I suppose.

With the pressure plate removed the clutch plate itself is revealed. Oily and slick. As the job of the clutch is to provide friction these are two pretty bad qualities to have.

A smear of leftover oil can be seen on the friction surface below. Oil where there shouldn't be oil is about as useful as a calculator in a Spanish exam in this setting.

So for a lovely, grippy and friction-filled time a new clutch plate saved the day.

 

A few more words of wisdom you wouldn't want your grandma to hear and a bit of struggling later and it was all back together. 

With the test drive complete having experienced no discernible clutch slippage I think the day could be declared successful! 

I'll get around to painting those arches sometime..

Time for new wheels!

Changing the wheels is probably one of the most instantaneously noticeable upgrades possible when modifying a car. I'd been waiting to upgrade ever since I got the car and when the day came it was glorious...

They look great but unfortunately in the images above that's pretty much all they made the car good for - looking at...

These wheels, being wider than the stock items, cause the tread of the tyres to stick out too far. If you're after an MOT that's a no-no around these parts. The tread of the tyre must be covered by the arch. So although they look pretty damn cool in the above shots, the standard arches had to go!

Another perhaps more important problem is the fact the wider wheels foul the metal of the arch making full lock unattainable. Standard arches off...

 Identifying the offending section of arch...

and marking out what needs to go with skilfully-applied masking tape and blue felt tip...

There are some out there who might think cutting away some metal just to fit new wheels is a bit barbaric.. it is.. but I have tried to remove as little as possible.

By this point it was dark and raining. October in England. 

Next up.. arches! 

The waiting game with a slipping clutch...

Clutch slipping. Losing oil. Waiting for parts. A necessary part of any build/repair/car procedure.

But when your car is just sat in the garage it seems like forever.

The arrival of the primary gear/clutch oil seal tool, flywheel puller and new seal!

Not an overly simple task by any means but doable. It involves having the clutch and flywheel assembly out...

...and removing the primary gear...

When the clutch is slipping in these cars it's apparently most often caused by this little red seal pictured above. It's supposed to keep oil inside the engine and away from the clutch and flywheel assembly. If it fails (which it had on my car) it sprays the clutch and flywheel with oil and causes the loss of friction resulting in a slipping clutch. Although time consuming and requiring a few special tools (all around the £20 mark) it wasn't too difficult. 

The time consuming bit is the disassembly and reassembly..

All back together again now. The clutch is still slipping but I suspect that's residual oil left on the flywheel and clutch assembly which should burn itself off after a few miles. I hope. Time will tell!

Next up.. Wheels and arches!

Mini Project

I recently acquired a Mini in need of some tender loving care. It took a couple of weeks to arrange but by the time the car was towed to my garage I was itching to get started. 

Room to do the work was a slight issue. It's a tight space - even for a mini. 

It turned out the head gasket had failed..

The head gasket is a thin piece of material (not literally material - it's usually metal) that sits between the cylinder head and the engine block and forms a seal between the two. In the picture above the tops of the pistons can be seen along with the other passageways for oil and water. Oil and water have to be circulated throughout the engine and up into the cylinder head. When the head gasket fails the oil and water mix together resulting in watered down oil and not enough water in the system. It's bad news all round for the engine and the resulting heat can warp the cylinder head. Luckily on these Minis the cylinder heads are cast iron (as opposed to aluminium) which is much less likely to warp so the cylinder head usually doesn't need to be skimmed. 

Along the way sacrifices were made..

Usually the head gasket doesn't just fail on its own. It's more likely to be a symptom of something else. In this case the water pump was at fault. Inside the water pump (pictured below) is a bearing and a seal. The small hole that can be seen on the top/side of the pump is a vent hole for the bearing as it can get very hot. On the old water pump the seal had failed which allowed water to pass through it and out of the bearing vent hole. Less water  in the system - less efficient cooling leading to engine overheating and head gasket failure.

Nice new water pump arrived..

Then onto the rebuild.. 

Fingers were crossed as the car went for an MOT.. and it failed. One of the front brake calipers was seized. Back to the garage and the problem was worked through. 

And then began many months of trouble free motoring..

Or so I'd hoped.. On a blast around the other day the clutch started to slip badly. No rest for the wicked.. More to come..