mark newman Posted June 29, 2014 Share Posted June 29, 2014 As Title and if valve clearance can change , would the clearance get bigger or smaller. any help would be good, as I'm trying to find out why after the machine shop shimed my head , they or now to small, and need to be re-done. machine shop said that they were done right. the only way that they have changed is that my valve springes are to strong at 110 pounds and are pulling the valves into the head,? or all changed when i bolted the head down. most of the measurments are at 0.15 that is on the in and out. What would you think. EX IN 12 0.20 12 0.10 11 0.15 11 0.10 10 0.20 10 0.15 9 0.20 9 0.15 8 0.15 8 0.10 7 0.15 7 0.15 6 0.15 6 0.10 5 0.15 5 0.15 4 0.15 4 0.15 3 0.15 3 0.15 2 0.15 2 0.15 1 0.15 1 0.15 --------------------------------------- Quote Link to comment Share on other sites More sharing options...
TBDevelopments Posted July 2, 2014 Share Posted July 2, 2014 Yes it can. Valve clearances should always be checked again once everything is bolted down Tim Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 2, 2014 Share Posted July 2, 2014 How can valve clearances change from bolting down a head? when an OVHC engine nothing can affect the clearances, unless the valve seats are re-cut or reground after the shimming has been done, or the valve collets have been replaced afterwords, the valve springs will make no difference at all. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 2, 2014 Share Posted July 2, 2014 The collets won't affect bucket to back of cam lobe clearance. I have never seen, nor heard of valve clearances on true OHC direct acting valve trains changing with the head off the engine, to being torqued onto a block. Quote Link to comment Share on other sites More sharing options...
TBDevelopments Posted July 3, 2014 Share Posted July 3, 2014 its just common practice to check after torqueing down the head, as the torque from the head studs will distort the alloy slightly which interns slightly effects cam clearances. Toyotas don't suffer badly from this but engines like the lotus twin cam are one for example that does and its often seen that perfectly shimed engines will go overspec loose when all bolted together. But its just a common build practice. Its a similar principle with the engine block about pre-tensioning the casting before you bore/hone the engine. Tim Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 3, 2014 Share Posted July 3, 2014 Sorry Chris, of course collets wont, it was late and not thinking clearly, But as far as heads distorting enough to alter valve shim clearances, if that was the case then there would be an awful lot of snapped cams about due to distortion of the journals. Quote Link to comment Share on other sites More sharing options...
TBDevelopments Posted July 3, 2014 Share Posted July 3, 2014 Just passing on my experience with engine building mate, wasn't trying to turn it into a pissing contest. they will normally open up but will depend on the engine application, like i said the old lotus twin cam used to open up alot. Toyota 3sgte doesn't really suffer from it. Toyota 4efte does a small amount. Tim Quote Link to comment Share on other sites More sharing options...
mellonman Posted July 4, 2014 Share Posted July 4, 2014 for the time it takes to check , why not just for peace of mind Quote Link to comment Share on other sites More sharing options...
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