112.8mph Lucky Poos Needed

FX_Munkee

The aerodynamics of a MK1 MX-5 are poor with or without the roof, in fact there's not much difference between the 2. The only aero that makes some appreciable difference is a front splitter to weight the front at high speeds. They tend to get " a bit light" at > 80mph

Our American cousins did a load of testing on this about a decade ago and this is what they came back with, and it's been proved correct by all the empirical evidence I've seen.

RiftAmps

FX_Munkee said:

The aerodynamics of a MK1 MX-5 are poor with or without the roof, in fact there's not much difference between the 2. The only aero that makes some appreciable difference is a front splitter to weight the front at high speeds. They tend to get " a bit light" at > 80mph

Our American cousins did a load of testing on this about a decade ago and this is what they came back with, and it's been proved correct by all the empirical evidence I've seen.

+1

When we eventually upgrade to an ITB setup and move up a class to 180bhp/tonne, we should be able to overcome the inherent drag of the car.

TWP Racing built theirs with a hardtop, custom cage, and a BGW. They then had to do a 1.8 VVT swap with many mods/tuning to get it to be a class-winning machine.

RiftAmps

Cylinder Head

The first step is to reinstall the oil galley grub screws into the head. Coat the threads in RTV and snug up by hand.

Then mask up the important bits and give it a coat of high-temp primer, then black paint. Went for gloss this time.

FX_Munkee

Since you started this thread I keep taking a second glance at the engine with blown rings I have sat in the corner of the garage every time I'm in there.

It's been there for over 10 years...

RiftAmps

Now we need to strip, clean, and reassemble the 16 hydraulic lifters.

The plunger assembly broken down into its component pieces

and then soaked in brake cleaner to remove all old oil, varnish, and other crud. The bucket it cleaned too.

reassembled...

...then soaked in mineral oil (15w40) until ready to install into the head

FX_Munkee

I have always kept the HLAs "numbered" when I've taken them out, so they always go back in the position they came out of.

RiftAmps

Time to start assembling the cylinder head

Here are the 16 valve spring seat washers - they sit between the base of the valve spring and the cylinder head itself, protecting the head from damage.

After a clean with brake cleaner, they're dipped in oil before being placed into the head.

RiftAmps

Now we have to install the valve stem seals - these stop oil from the cylinder head making it's way down the intake and exhaust valve stems and into the combustion chamber. These, along with faulty piston rings are the main cause of excessive oil consumption in an engine. It's always worth changing these out when you get the cylinder head apart.

I have a special pair of pliers just for these, used for both removing and installing them onto the valve guides.

Push it on gently and you'll feel it 'pop' into place

RiftAmps

Valves and Valve Seats

Whilst the head was in the shop we took the opportunity to have the valve seats and valves cut with three angles - 30, 45, and 60. This is quite a popular engine mod as it allows for better airflow both into and out of the combustion chamber.

Here you can see the valve seats with the three angles

...and one of the valves with the matching back cuts

RiftAmps

The valve is placed into the head, then the valve spring and retainer are compressed with a valve spring compressor tool. Once the spring is down far enough the retainers (collets) are placed around the valve stem and then the tool is backed off.

Repeat 15 more times.

RiftAmps

Because we've opted for head studs rather than head bolts, we need to install these washers to protect the head from the head nuts. They're coated in ARP ultra-torque lube and then placed into the head before it's mounted onto the block. Owing to tight clearances in the head, you can't get these on afterwards so must go in before.

RiftAmps

Head gasket is placed onto the block, the head studs make it very easy to get everything lined up and in place. We use a standard head gasket rather than a MLS, no need for <200bhp.

The stud threads are coated in torque lube too.

Head is placed onto the block.

RiftAmps

The head nuts are fitted then torqued down in three steps 48-68-88Nm. The torque pattern is an outward spiral.

RiftAmps

Next up is mounting the alternator to the block. I had an old broken one on the shelf so PX'd it against a new one from ECP which saved me £35.

RiftAmps

Camshaft Install

These are regrinds from Piper, to their 285H spec offering .350" lift at 256ø intake and 266ø exhaust duration - Same spec as we have on the car currently.

Firstly we place all 16 refurbed hydraulic lifters into their bores. The bore walls were coated in assembly lube, along with the camshaft journels.

here, the intake camshaft is lowered into place. The lobes and journels/bearings are also lubed up.

RiftAmps

The camshaft caps are placed into their correct position.

Then torqued in an outward spiral pattern, in equal stages to 14Nm.

Repeat for the exhuast camshaft

RiftAmps

I forgot to RTV the camshaft end caps so had to pull them out to do so, always forget to do something!

With the end caps back in I can fit the camshaft oil seals. A little engine oil helps slide them into place being careful so they sit flush with the head.

RiftAmps

Now we fit the upper rear timing cover, I gave it a fresh coat of paint as it was looking a little tired.

6xbolts keep it in place.

Now the camshaft sprockets are installed, the bolts are torqued to 60Nm with blue loctite on the threads. To stop the camshafts turning when tightening the bolts a locking tool is placed in between the sprockets.

RiftAmps

Cambelt Install

Our first job is to rotate the crankshaft to top-dead-centre, cylinder #1. The crank pulley has a half-moon cut-out that should line up with the timing mark on the oil pump casing. There's also a tensioning mark at 10 o'clock which we'll talk about later.

With both the crankshaft and camshafts lined up in their correct positions, the belt can be slipped over the sprockets and pulleys starting at the bottom and working around in an anti-clockwise direction.

I've marked the camshaft sprocket timing marks with a paint pen. With the belt in place there should be 19 teeth inbetween the two marks.

RiftAmps

Close up of the crank pulley with belt in place.

Now I fit the bottom pulley and bolt so I can turn the engine over. We rotate it clockwise nearly twice around until our little half-moon cut-out lines up with our tensioning mark (see above).

At this position, the belt is not under tension on the left hand side, so the tensioner spring can be fitted, pulling the tensioner pulley into place before torquing down the bolt.

The engine is then turned over twice again and all timing marks are checked and verified.