Well just got a set of heads back for a motor im doing.Had four guides four valve seat inserts .All new valves as well all supplied by me .Got charged 750 bucks for the work which I thought was a bit steep but tried twenty or so machine shops including major engine rebuilders.And this guy was the only one that said he can do them.He said he has done plenty of shovel and pan heads before so i left them with him. Well having paid for work before and it was done wrong I thought well im not going to take his word that they are good to go.Keep in mind that I gave him my shop manual so he had all the correct specs.Well got up this morning and went to the shed and pulled the rear exhaust valve out to check the specs and guess what it aint right grrrrrrrr .minimum valve sticking out the head when measured from the shoulder of the guide is 1.375 ive got 1.345.wtf IM no engineer but I reckon the valves will hit the pistons.How the f---k do you get that wrong when ya have the specs in front of you .So ive got this right if there is less than the minimum there is to much valve in the combustion chamber . And a good chance they will hit the piston on compression stroke
For what its worth,I would clay the heads and see if they will hit.I paid 800 for mine to be done.Just told him I was running the r5 cams with wiseco forged,sent them out,3 weeks later,walla.PERFECT.Call Jim at Megaflo near pittsburgh.Hes a one man machine shop that has been producing top wins around the world for sportsters and shovels.He can help!!!
The max/min spec for valve stem protrusion is to insure proper rocker arm geometry, not piston-to-valve clearance.
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Ill have to chime back in.He did do a complete rework and changed the geometry on the valves and seats and reworked the bowls.It was well worth the price.Simply suggested a call to him for technical help