valve clearances

[twotone sprint]

I wondered if anyone had anythoughts about this?? Yesterday I took the rocker cover off my 1974 sprint to measure my valve clearances. Inlet clearances are between 15 and 17 thou and exhaust are between 13 and 15 thou. The engine has only done 500 miles since I put it together. All is running well apart from a tapping sound from the head.The valves were reground by my local machine shop and they said they re-shimmed to reset the valve clearances. Unfortunately I did not check these prior to refitting the head otherwise I would have re-shimmed it myself to 18 thou. Will clearances of these values be very detrimental to the valves, am I right in thinking they will open further and longer than necessary? Are they likely to bed in much further? If I need to re-shim the head would I get away with removing the rocker gear with the head in situ by removing its retaining bolts and the four top head studs, thus not having to change the head gasket again? Or is that just wishful thinking on my part.<br>
Any advice would be appreciated.

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[alun n]

Jonners (inter alia?) will argue with me on this one, but if you drain down the coolant using the block plug and slacken all studs and bolts in the appropriate order before removing those you need to and when finished re-torque in the correct manner there is little reason in my humble opinion why the gasket cannot be re-used as there should be no compromise to it. I've successfully re-used headgaskets previously in my poor days, albeit not on a Sprint.

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[Jon Tilson]

Alun I completely agree with you....<br>
If it were mine I would do it exactly this way...<br>
Make sure you retorque all the bolts in the correct order.<br>
If you have a tapping noise look for a worn finger rocker and cam lobe.<br>
Jonners

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[Malc]

I've not done it this way mysen, but have heard of people swoping cams without lifting the head. One thing for sure, make sure the motor is stone cold (leave it standing AT LEAST overnight. Sprint Folklore reckons that many a Sprint H'Gasket failure was due to 'nipping' the head down on a warm or even hot motor. Slacken bolts and studs progresively. I might also be tempted to leave a 'few' lbs torgue on the head bolts to reduce that chance of anything moving. If all goes well <!--EZCODE EMOTICON START :D --><img src=http://www.ezboard.com/intl/aenglish/im ... /happy.gif ALT=":D"><!--EZCODE EMOTICON END--> , if not, the head will have to be off, all you loose is a bit of time

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[twotone sprint]

Thanks, I thought I might be able to do it this way but wasnt sure. As for the tapping, the cam lobes look fine, so I'll give the rocker gear the once over when it comes off. I have a spare set anyway, if necessary can I just replace the offending rocker arm and re-shim to suit?? The tapping dissappears at higher revs and on acceleration and is most noticeable between tickover and 2000. I wouldnt have thought the valve clearances I measured would have been responsible for this???

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[Chris Field]

When you measure the clearance with a feeler gauge you dont always get the true clearance because the wear takes place in the centre - you get a dish in the center of the cam bucket so what you end up measuring is the distance between the rocker and the outside edge of the bucket - which doesn't tell you the gap between the two points of contact. Once they are worn you can only really measure it with a DTI - but by the time it gets that bad you should be replacing them anyway!<br>
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Perhaps someone can explain that better than me!- wish I kne how to put drawings on here!<br>
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