Was fine, now confused - Setting Hydraulic Tappets

[T25Convert]

Hello all,

I'm now confused! I thought I had the setting of hydraulic tappets sorted thanks to Haynes, Ratwell page and on here, but now confused by this post:

Tappet preload only applies IF the cam followers are "dry" and not full of oil, in which case any preload will simply jack the valves open and you will have no compression at all.
I have just finished an engine which had new hyd lifters on a new cam, 6 of the 8 were dry (apart from a bit of packing oil) the other two were solid, so I had to pop the clip out and drain them before reassembly.
If you can't push the little piston down in the follower and feel it spring then you can't set the preload with any degree of certainty.
I only give them 1 turn preload, that equates to 1mm of wear at cam or a lot of valve recession!

I was under the impression that it was a case of pump up the tappets until they are firm, then screw them in somewhere between one and two turns. However this ^^^ makes sense...

Very confused!

Thoughts?

Cheers,

Alex

[mickeyflyn]

I'm about do do mine next week and the way I understand it is if you leave the engine for a couple of days the followers will drain down and it should be ok to adjust then. don't take my word though ask someone here before your attempt.

[123-jn]

The followers need to be full before fitting and adjustment, if they are drained down it can';t be done accurately. AT TDC on firing stroke Release the screw until there is a clearance and had tighten to remove play now 1.5 turns and tighten the nut. Yes they will hold the valves open but after a couple of revolutions they will adjust themselves and she will start, some lifters may take a few more moments but all should then be good. If they are drained down you need to adjust to a very slight clearance then run the engine until it pumps up, then pull the cover off again and set that valve.

[T25Convert]

Thanks 123-jn, that's what I'd been doing, but after the post by silverbullet seems to contradict, and given his clear expertise in automotive engineering it's confused me!

Van runs find though, so happy with it as it is!

Cheers,

Alex

[bigherb]

Tappets must always be filled and bled before fitting. As 123 said the tappets are adjusted full with preload so the tappet can adjust itself if there is no preload then the piston can go to full travel and may damage the tappet.