Club 80-90 Forums

No sign of even the slightest ripple from ring wear (think that I can see honing marks across TDC, I can typically feel 0.0002" and thats half of buggerall in old money) so I'm even more certain that it's been rebuilt before.

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Had a bit of a misfire apparently. Can't imagine why, what with these pristine spark plug sealing washers and spotless seatings?
All caused by leaky hoses and glycol coolant, for the most part.

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I think you're quite enjoying the detective work on your "unknown" engine

937carrera wrote:I think you're quite enjoying the detective work on your "unknown" engine

A contender for 'Understatement of the year' methinks

Oooh good, what's the prize, a freshly rebuilt WBX 6 (I wish)

Any prize will be similarly understated

Its true, I do enjoy going a bit phorensic on an engine

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Bit of a game to get a working set-up on these heads to drill out the exhaust port bolts, being as they are about 400mm long!
Ended up hanging the head off the front of the Bridgeport table, winding the knee to the floor and there was just enough space left for changing drill bits etc.

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Funny, I started to remove a broken stud from my "unknown" engine on Friday. As I was doing it with my hand held drill I thought of you and the setup you would be using. I wasn't wrong.

They're very hard aren't they, I did about a dozen on another engine last December and they were relatively easy with the same fairly decent drill bits. What are you using ?

For M8 x 1.25 I use a slot drill to get the end of the bolt/stud square, then take my best shot at finding the centre.
Spot/centre drill, then drill down the middle at around 5mm, then go just into the first turn of thread with a 7mm slot (to check/correct that I am in the middle)
If it needs correcting, then I will probably core it with a 1/4" slot, before drilling out to 6.8mm but... if its a corroded-in stud it may well rip the threads out, in which case:
Helicoiling. I will continue with the 7mm then size with the 8.3mm before tapping for the insert.

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PS you can get remarkably good results down to M6 by using a guide bush to keep the drill central and square but... squaring-off, centering and getting enough pressure for the drill to cut (not rub) are the challenges.
The moment you encounter high-tensile or stainless fixings, its time for machine tools or at the very least a good pillar drill and an angle plate.

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I haven't had too much issue getting the drill centred, or at least close enough to centre to drill studs out to a certain point and then remove the remnants before cleaning the thread. On a couple of occasions I have had to helicoil, but not an issue

I haven't previously had an issue getting the drill bit to cut.

I'm using some DeWalt drill bits at 2.5 and 3.5mm, as well as some decent engineering quality HSS bits I have at 4mm / 5mm - I have tried resharpening the bits

*insert grownup word*

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Only me!

Now, I do not believe you wanted to do that, did you?

Why is that valve guide still hugging the valve stem then ?

It's loose on the valve and in the head... I have some suitable aluminium bronze CA103 (highly wear resistant) to make some "top hat" exhaust guides that can't fall into the engine.
Just gauging the situation...

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