Author Topic: 90+ valve guides  (Read 286 times)

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Offline tck

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90+ valve guides
« on: 04 Feb 2021 at 16:27 »
On my crossbreed MK4 one of the 90+ heads had a cracked exhaust guide it is being replaced by an engineering firm it looks as it the standard guide 35537 can be modified to fit bit I note that the cracked guide has a small vertical slot in the protruding head of the guide I cannot see what that was for any ideas?

Offline Neville Heath

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Re: 90+ valve guides
« Reply #1 on: 05 Feb 2021 at 19:25 »
There is an oil feed slot milled down Plus guides that feeds a radial hole to lubricate the valve stem.
Neville

Offline tck

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Re: 90+ valve guides
« Reply #2 on: 06 Feb 2021 at 15:02 »
You are right the path in the head was blocked with carbon it does not seem a particularly effective idea perhaps for racing with lots of stripdowns?

Offline Neville Heath

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Re: 90+ valve guides
« Reply #3 on: 11 Feb 2021 at 10:32 »
Everyone I have ever come across has been blocked with carbon. As you say O.K. for one race probably. I still clean them out though!
Neville

Offline Neville Heath

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Re: 90+ valve guides
« Reply #4 on: 11 Feb 2021 at 10:51 »
Photo of Plus guide. Note seat is also tapered, not flat like Mark.
Neville

 

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