Thursday, May 24, 2012

NACA Scoop

Hi All,

Well what have I been up to recently ? Still no time to play with the MG.

SVDP racing are going to enter the Bareclona 24 hours, so we are running round like mad trying to get a very long list of things done.
One of them is to fix the bonnet, a recent locking pin “incident” resulted in it flipping back going down the pit lane. As  a result some GRP work was required. As part of this one of the jobs that also needed doing on the bonnet was the NACA scoop, at the moment there is a horrid ABS plastic unit bolted with nutserts to the bonnet and sitting proud.

Well I thought I could do a lot better, so here we go.
This is the original scoop, it sits about 10mm proud at the front, hardly the streamlined and aerodynamic venturie it is supposed to be.

First step is to make a wooden mould (or buck) cover with bondo, multiple coats of paint, release wax and release agent.

Then lay on the carbon fibre. I used 200g 2-2 twil, four layers on the main part but only two on the flange to give the flange some flex to contour the bonnet properly.

Did I mention mould release ! hmm, yes I did use lots. I think the sides were too vertical for good part release, never mind.
A bit of clean up and here we are.

Not a bad finish.

Some balsa cross bracing on the back side,

190g and strong enough to stand on !

All I've got to do now is sand it, lacquer it and then fit it into the bonnet.
Richard B.

Next . . . . . do the rest of the work on the bonnet.

Thursday, May 17, 2012

Down the plug hole, the glow plug hole.

Hi All,

This is the results of a recent internal borescope examination of the engine in the SVDP BMW 120D race car. I am putting them up here more as a photo dump as well much as anything else.

The image quality overall seems poor, however, on the camera while you are looking around inside the cylinder the image quality seems much better. The video helps but still not as good as you see.

This is the video.
You are traveling down through the injector hole (glow plug hole is to small).  You will see the liner passing top left to bottom right.

Cylinder 1
 Glow plug
 Liner, note the long scratches, these are normal wear. The black spots are inclusions.
 The back side of the air inlet, quite black and sooty.
Cylinder 2
Glow plug
Liner, heavier striations.
Back side of inlet valve.
Cylinder 3
Glow Plug
 Liner, lots of striations and inclusions.
 Back side of inlet valve.
Cylinder 4

 Glow plug
 Liner, heavy radial mark, lots of marks.
 More marks and inclusions.
Back side of inlet valve.

Richard B.

Tuesday, May 8, 2012

What's the point - Points and Timing

Hi All,

Well continuing on trying to solve the problem, its time to do the distributor for points and timing.

Apparently the problem is here !

Hmm, a little TLC needed.

 This is her off.

a 25D 4

And the serial number in case needed later.

Not to bad but the DPO told me digital points had been fitted !
Hmm these definately aren't.
Gap was also way off.

Ahh but this is a problem the ground for the advance plate is not connected.

Mechanical advance all a bit crummy.

All in bits and time for the part washer.

Cleaning up nicely.

Testing the vacuum advance.


Under vacuum (it has moved, honest).

Points gapped and it looks better.

My way of marking the distributor cap. Simple and permenant.

All done.

Back on.

Setting the timing .

Then fire her up and . . . . . . . Run, race, stall, start, stall, splutter, start, not start.
Damn ! problem not solved, so on to the carbs next.

Richard B.

Next . . . . . . Carbs again, this time properly not a quick and dirty blast with carb cleaner.

Pressures on - Compression testing

Hi All,

After the ride of shame it was time to try and sort the problem
The  traditional order is valves, compression, points (dwell), timing, then carbs.

Valves were for once nice and I believe that there is a new head like the DPO said.

Compression, sadly a mixed result.
- Firstly dry
No.1, 117 psi, Okay, not great but see what the rest are like.
No. 2, 121 psi, hmm.
No.3,  115 psi, still hmm.
No. 4, 150 psi ! definitely not a good sign.

- Then wet, with a squit of oil.
No.1 = 120 psi, still not great but means rings are not to bad.
No.2 = 138 psi, damn quite a rise so rings not good here.
No. 3 = 137 psi, same as No.2.
No.4 = 170 psi another high one.  It’s one thing being low at around the 120’s any significant difference between cylinders is also not good.

I suspect / know a rebuild is now in the near future. However, she should run okay for a while.

While the plugs were out time for a quick play with my new toy a bore scope !

All seems okay on the liners with honing marks still visible. Suspect she may be a bit loose as the the last rebuild might have just been honed and not bored oversize.

No. 1 Liner

No. 1 Crown
No.2 Liner

No. 2 Crown

No.3 Liner

No.3 Crown

No.4 Liner

No. 4 Crown

No.4 Valves (not a good picture).

So problem not fixed and a one coming in a while.

Richard B.

Next . . . . . . Points and distributor.