stretch
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| posted on 23/10/09 at 08:01 AM |
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crossflow oversize valves replacement
took the valves out last night and it seems there is quite a lot of play on them
its the maximum size valves that can fit - bought the head with them fitted
what are the steps to resolve this? new valve guides? etc?
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daviep
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| posted on 23/10/09 at 08:52 AM |
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You need to measure the valve stems and the valve guides and find out where the wear has occured. Worst case is you'll need to get a new set of
valve guides pressed into the head and a new set of valves.
Regards
Davie
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Chippy
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| posted on 23/10/09 at 09:01 AM |
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May be wrong, but arent the valve guides on a Xflow machined into the head, seem to recall that they were. If so the head will need line boring and
valve guides pressed in. As said may be wrong, many years since I played with a Xflow. Cheers Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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02GF74
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| posted on 23/10/09 at 09:27 AM |
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yes - the valve guides are part of the cast head.
to replace, need to be bored in and new guides fitted.
in the olden days, according to the Haynes manual, oversize valve stems were available but not any more.
take a look at pinto valves - they are bigger than the crossflow but the same length, the stem I think is a tiny bit bigger - could be a cheap way to
go oversize but only on the exhaust (the inlet is too big - or is it other way round).
I went oversize on mine
in 41.3 mm ( canget 43.7)
ex 34.9 mm ( can get 36 mm)
you can go bigger than that but then the guides need to be offset and to counter that, the valve springs need to be machined.
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thunderace
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| posted on 23/10/09 at 02:13 PM |
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quote:
Originally posted by 02GF74
yes - the valve guides are part of the cast head.
to replace, need to be bored in and new guides fitted.
in the olden days, according to the Haynes manual, oversize valve stems were available but not any more.
take a look at pinto valves - they are bigger than the crossflow but the same length, the stem I think is a tiny bit bigger - could be a cheap way to
go oversize but only on the exhaust (the inlet is too big - or is it other way round).
I went oversize on mine
in 41.3 mm ( canget 43.7)
ex 34.9 mm ( can get 36 mm)
you can go bigger than that but then the guides need to be offset and to counter that, the valve springs need to be machined.
wow i was sure the max was 41.3 
mine are around 1mm apart and i was told could crack where they meat as were so close after spending weeks porting polishing and cleaning the head
up
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bmseven
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| posted on 23/10/09 at 03:43 PM |
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What state of tune are we talking and define quite a lot of play?
http://www.cncheads.co.uk/ford_crossflow.html
BMW 7 Resource
Bures Pit anyone?
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ncoll
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| posted on 23/10/09 at 04:13 PM |
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If your valve stems are not badly worn, take the head along to an engineering shop and get some k-liners fitted. These are about £6.00 each fitted.
Much cheaper than having the head bored and individual guides fitted, plus they are longer lasting.
ncoll
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