tappet pre-load help please

[thegriff]

Hi all.I am going to fit new tappets that will hopefully cure the tapping noise when hot.A new cam and tappets were fitted about 4000miles ago by previous owner through a garage and upon close inspection the cam looks good,I am hopeing that either a tappet has gone awol or the pre-load is wrong.I understand the method but do the tappets need to be "charged" up with oil first for a correct reading? If so how do you do this,I covered the tappets in oil and spun her over on the starter,but the new tappets are still bigger gap than the 50thou max tolerance.I have read that you should not use new on old but I feel that since the cam has only 4000miles on it and looks very good I am chancing the new tappets. Thanks for any help on this guys simon

[GreenV8S]

Mixing new/old valve train components is universally regarded as a bad idea, but it's your time and money.

You don't need the lifters full of oil to set the preload, they are sprung open and the preload is a measure of how far the valve train holds them closed on the back of the cam. How much preload variation are you getting across the followers? If you have any uneven wear elsewhere in the valve train it may be that one particular lifter has the wrong preload. For example I had a worn pushrod on mine which caused a light tap because it took the preload off the corresponding tappet.

I assume you know about the cam/lifter bedding in procedure and how critical it is to do this correctly.

[dickymint]

Good info here (scroll down).

www.rpiv8.com/faq-gen.htm#preload

[gsx600]

I seem to remember on mine I imeresed them in a bowl of oil overnight and pushed and released them so as to get the oil in every part. Had no problems since.

[rev-erend]

When you have the valley gasket off - did you check that the cam had no up / down movement (indicating shagged bearings..)

I'm no expert in this area but if the clearance at the tappet seems excessive then maybe that's the problem.

Mines a solid lifter but clearance is 12 thou.

[thegriff]

Hello again,Just fitted the new tappets :dry: and checked the pre-load,the first tappet I checked is over 100thou and the others looked to be the same.I slackened off the rockerbolts evenly to achieve a pre-load within the 20-60thou tolerance and measured the gap underthe posts,I need 60thou shims.All the rest of the valve gear seems to be in good condition.My wedge is a 400se( just thought I mention it in case the pre-load is different,you never know! ) I would like to know how to bed the tappets into the cam?
Any thoughts about the above would be gratefull,cheers simon

>> Edited by thegriff on Monday 24th April 21:04

[GreenV8S]

Preload needs to be set per engine, and you need to measure the preload on all the lifters and then choose shims that give you the best average setting.

The bedding in procedure is basically to assemble everything lubricated and then run the engine at over 2000 rpm for twenty minutes. Don't let it idle for any reason; if you have any problems switch off.

[thegriff]

motor not doing a tap dancing routine anymore! job done,thanx to v8 developments fot advice and shims and a BIG thanx to all you fellow wedgers for your help. simon

[pwd95]

Nice one Simon, see you soon.