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By Ricks56 - 9 Years Ago
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I know the valve clearance on a Y-block should be set to .019" when the engine is hot. Do any of you set them cold and what gap do you use?
Thanks
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By oldcarmark - 9 Years Ago
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There are several different ways to set Valves Cold. Basically 1/4 turn from Zero Lash will give .020 clearance. If the Rockers are not flat on the Pad that contacts the Valve from wear its really the only way to get an accurate setting. Feeler Gauge will be inaccurate because the Pad on Rocker is not flat. Personally I do each Cylinder in the firing order by turning the engine 1/4 turn and adjusting both Valves on the next cylinder in the firing Order. Others on this Site have their own preferred order of adjustment. There is an article by the late Walt Knuckle explaining his method of adjusting valves using the 1/4 turn Method.
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By Ricks56 - 9 Years Ago
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I guess what I was wondering is should the gap spec be increased for a cold setting? I set them cold last year using the 1/4 turn method but have been thinking ever since about how much the gap changes when hot.
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By Talkwrench - 9 Years Ago
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Don't over think it.. It wouldn't be much or people wouldn't use that method, never had a problem doing the "Walt Knuckle" method.
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By Ricks56 - 9 Years Ago
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I guess I'm not being clear enough. The shop manual says to set the valve clearance to .019" with the engine hot. If I set them with the engine cold is .019" gap enough? If so, why do they specify to set the valves when the engine is hot? It sure is a lot more comfortable and safer to work on a cold motor!
Thanks
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By 57RancheroJim - 9 Years Ago
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I set mine cold for the first start of my new engine, I set them at .019. After running a break in for 20 minutes I rechecked them HOT and they were at .017. So mine changed .002. Not that every engine would be the same.
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By Ted - 9 Years Ago
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Most iron headed engines with solid lifter camshafts will have the lash tighten up about 0.002” from cold to hot. Setting the lash at 0.021” cold will have the lash at approximately 0.019” when hot on most Y's. This is a result of both valve stems and pushrod lengths growing as those pieces get warmer.
Aluminum headed engines are the opposite in that the lash will loosen as the engine gets warmer. As the aluminum cylinder head warms up, it grows upwards away from the camshaft thus resulting in increased lash. The Y with aluminum heads will need the lash set approximately 0.006” tighter when cold versus what you want when the engine is hot.
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By Ricks56 - 9 Years Ago
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Thanks guys! Exactly what I was looking for.
I think I should be fine if I adjust the rockers 1/4 turn from zero lash on a cold engine and not worry about it any more!
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