DJ valve clearances - has the manual got it wrong?

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GreatCrestedNewt
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DJ valve clearances - has the manual got it wrong?

Post by GreatCrestedNewt »

I've just put back together one side of my DJ engine after sorting out a head problem and was puzzled to find that I had no compression on either cylinder.

After head scratching (mine not the engine) I checked the valve set up instructions again as per Haynes and Bentley - both of which instruct to turn the adjuster in until contact with tip of valve and then two further turns clockwise before locking off.

I thought it seemed a bit odd as the springs were starting to compress but followed the manual anyway thinking that it might be something to do with the hydraulic valve lifters. Still no compression so I slackened them off again and this time just screwed in until there was light contact with the valve and then locked them. Compression restored, engine running sweetly and me a bit bemused.
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Re: DJ valve clearances - has the manual got it wrong?

Post by SyncroSwede »

Syncrosimon and I did mine a few weeks ago. We seemed to wind an awful lot off (4 turns) before getting a slight gap then set them all at 1 & 1/2 turns as advised by an article on the Samba I think. The engine needed a whole lot of cranking before it would fire and guessed that was the lifters setting themselves. Seem to get much better low down torque and improved economy now although still quite tappety.
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Re: DJ valve clearances - has the manual got it wrong?

Post by Simon Baxter »

1.25 turns works for me on used lifters that already have some oil in. I think empty tappets then yes, 2 turns but used and full 1.25 works well.
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Re: DJ valve clearances - has the manual got it wrong?

Post by sandwedge »

Sorry if youve already done this, but did you set the engine to TDC on each cylinder before you set the pre load on the valves?
If you didnt turn the engine over to TCD for each cylinder the valves maybe open, hence no compresion.

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Re: DJ valve clearances - has the manual got it wrong?

Post by syncrosimon »

I would do the adjustment again now that the engine has run and the lifters have some oil in them. I believe best practice is to do the lifters after the engine has run for a bit and is not making that dreadful clacking noise.

These lifters have a limited range within which they allow the valve spring pressure to fully shut the valve against the internal oil pressure of the lifter, and where under no load ie at TDC the engine oil pressure will fill and expand the lifter to take up the slack. Finding the sweet spot seems to be very different for each engine.
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Re: DJ valve clearances - has the manual got it wrong?

Post by ghost123uk »

I had the same issue as GreatCrestedNewt when I last did mine (cold).
I backed them off, warmed the engine up, and did them again, with 1/12 turns in after contact.
That worked :)
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