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Valve guides (exhaust) for DJ engine?

Posted: 29 May 2014, 10:43
by Hoopy_Frood
There are two sizes for sale on Brickwerks, 13.07mm diameter and 13.045mm. Is there a way of knowing which one I should get?

Thanks

Iain

Re: Valve guides (exhaust) for DJ engine?

Posted: 29 May 2014, 18:14
by itchyfeet
Like to know that myself and how to fit them and how to check if the 'play' is out of tolerance? :D

Re: Valve guides (exhaust) for DJ engine?

Posted: 30 May 2014, 22:08
by 123-jn
You need to either measure your valve stems or order the right valves to go with the new guides preferrably. Just a word of warning the haynes states that the maximum sideways movement of the valve head when in the guide is something like 1.2mm, That sounds an awful lot. Mine were measuring around .6 to .8mm so I reused the guides but the valve gear seems very noisy with this much play. I have recently replaced one of the heads which now has less than .2mm play in the guides and its very quiet compared to the other. So I reckon unless the play is no more than .2 ish mm change the guides and preferrably the valves too. I plan to replace the other head when funds allow.

Re: Valve guides (exhaust) for DJ engine?

Posted: 31 May 2014, 08:49
by bigherb
Hoopy_Frood wrote:There are two sizes for sale on Brickwerks, 13.07mm diameter and 13.045mm. Is there a way of knowing which one I should get?

Thanks

Iain
Not until you press out a guide.
When the guide is originally pressed in it squashes the ally around it, so a standard size guide would not a tight enough fit, how much it has squashed determines which oversize guide you need.
You determine which guide to use by the pressure needed to press it in, between 1 and 2 tons. If it is under 1 ton then the next oversize guide is needed.

Re: Valve guides (exhaust) for DJ engine?

Posted: 31 May 2014, 17:23
by what2do
1.2 mm??? Excuse my question here but where is the valve when measuring this movement? Today I removed the valves off a spare head that I have. With the valve just shy of it's seat there is barely any movement whatsoever. Just want to clarify this lateral 'play' for a better understanding.

Thanks.

Re: Valve guides (exhaust) for DJ engine?

Posted: 31 May 2014, 17:42
by bigherb
Pull the valve out till the rocker end is flush with the top of the valve guide then check. Should be done with a new valve for a more accurate reading.

Re: Valve guides (exhaust) for DJ engine?

Posted: 31 May 2014, 19:03
by what2do
That clears things up a bit cheers.

Re: Valve guides (exhaust) for DJ engine?

Posted: 31 May 2014, 20:20
by itchyfeet
bigherb wrote:Pull the valve out till the rocker end is flush with the top of the valve guide then check. Should be done with a new valve for a more accurate reading.


Thanks thats the really important bit of info haynes neglects to tell you
123-jn is that what you did?

Re: Valve guides (exhaust) for DJ engine?

Posted: 16 Jul 2014, 20:20
by itchyfeet
Ok so finally got around to checking the heads for my 'spare engine' which is in bits, checked Bentley which confirms what bigherb says, pull the valve out until the rocker end is level with the guide, bentley also gives a picture of the measuring setup.
As we are taking 1.2mm max used a vernier caliper rather than a dial guage referenced to a sheet of metal under the head, accurate enough for the purpose i think.
getting 0.3 to 0.8 so all within spec, happy now
:ok