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Hawkeye with 643HP the wheels.

Old 12 October 2017, 09:18 AM
  #121  
dazdavies
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I think crossing the line and hitting the limiter in 4th at 135mph is what's to blame for all this.

I think it's had valve float when the limiter has kicked in and I've had a bit of valve to valve contact. It's around 3-4 months since I did that and I think they've fatigued over time and finally let go the other day.

There's no other explanation as there is no sign of any contact on any other valves or pistons.

I think had I used Ferrea valves and had a limiter set at 8500 rpm I wouldn't be in this mess.

I need to see if the block is salvageable first. it's already at 100mm so if I cant hone out the marks this has left without going oversize then it's game over for the block which is a shame as its sleeved and is spot on.
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Old 15 October 2017, 12:54 PM
  #122  
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Good job I was planning that winter refresh on the engine. Pity the dropped valve beat me to it.

I've stripped the block down this morning. Bearings were on their way out. Rear thrust bearing, both halves were cracked!!

I've had zero mechanical sympathy for this engine so for almost 18,000m I think its held up pretty well but it was certainly ready for a refresh.

Piston skirts were in great condition. Bore of the dropped valve cylinder is damaged but I'm hoping an oversize rebore will sort that. I'll see what my local engineering shop has to say about that.

The current plan if the block is salvageable is for a set of CP 100.5mm pistons (purely because of the sleeved block), new heads, Ferrea valves and currentGTX35R turbo fixed by AET Turbos.

If the block is goosed then I'll have to bite the bullet and go the 2.35 route but I really can't afford one of the blocks at the mo so it will have to wait a few months.





























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Old 25 October 2017, 12:00 PM
  #123  
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So it looks like my engine failure was just down to the valves failing. Every single inlet valve has the beginnings of a stress fracture in exactly the same place that the others failed.

Just to clarify unlike last time that there are no signs of impact damage on either the valves or the pistons so it's just a simple materials failure.




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Old 25 October 2017, 12:16 PM
  #124  
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A simple, yet costly failure. At least you've found route cause with the failure, but it sadly doesn't help the situation.
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Old 25 October 2017, 12:37 PM
  #125  
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What valves did you use Darren?
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Old 25 October 2017, 12:47 PM
  #126  
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Supertech Stainless Niterided inlets and Supertech Inconel exhaust.

Supertech Double valve springs and Valve clearances were all set to cam manufacturers specs (Cosworth)
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Old 25 October 2017, 12:55 PM
  #127  
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Heard of a few failures with super tech and they’re supposed to be the best
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Old 25 October 2017, 01:11 PM
  #128  
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Did you check for coil binding on full lift ?
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Old 25 October 2017, 02:35 PM
  #129  
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Originally Posted by MOTORS S GT View Post
Did you check for coil binding on full lift ?
Haven't got the equipment to do it Paul, such as life for a home built engine.

It all came as a kit from the same manufacturer so you would think it would all work together. Heads were low mileage and I used stock guides and valve seats which were in good order and all checked prior to assembly.
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Old 25 October 2017, 02:57 PM
  #130  
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You can easily visually check for coil binding, get one of those dentist small angled mirrors & put the cam on full lift, you should as least have 1.5mm gap at the centre coils, they will closer towards the top & bottom.


Did you have thicker of the 2 options of spring platform, TS/SUB-4, if so they will be very close to binding, depending on your actual cam lift.
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Old 25 October 2017, 03:01 PM
  #131  
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Yes I do, Cosworth 10.8mm lift inlet cams.

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Old 25 October 2017, 03:10 PM
  #132  
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To be honest Daz, I would mock up your valve train & measure it, with those platforms 2.85mm thick, & cam lift, you will be surprised how little error there is, valves don't stress themselves on there own, something under lying usually does.
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Old 25 October 2017, 03:50 PM
  #133  
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Thanks Paul, I'll do exactly that.
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Old 01 November 2017, 01:00 PM
  #134  
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Thanks to a tip from Paul Finch (thank you Paul) I have managed to check for coil bind and I think I've ruled it out.

I measured the springs fitted into the head. Installed height with seat and retainer is 38mm.

I then put the spring assembly (again with seat and retainer) into a vice and compressed the spring to 27mm (cams are 10.8mm lift). Although it looked tight I could compress the spring another 2-3mm after this point.

Installed height (38mm).




Simulated full cam lift 10.8mm




So I'm assuming that rules out coil bind being the issue.
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Old 01 November 2017, 02:16 PM
  #135  
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I can't help, but this is a really interesting thread.
Good luck with the re-build.
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Old 26 September 2018, 02:57 PM
  #136  
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Hi Daz, did you ever get the car back together and get to the bottom of the issues? Been nearly a year now.
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Old 26 December 2018, 10:29 AM
  #137  
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Haven't touched it yet. It's sat in the garage gathering dust.

Had an accident in June which has put me out of action for a few months.
Will hopefully make a start on it in the spring.
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Old 02 January 2019, 09:58 AM
  #138  
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Originally Posted by dazdavies View Post
Haven't touched it yet. It's sat in the garage gathering dust.

Had an accident in June which has put me out of action for a few months.
Will hopefully make a start on it in the spring.
Sorry to hear that. At least you've still got it and it's a project with great potential when you get back on it again.

Happy new year!
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