hardened valve seats.

arcturus · Mar 1st, 2016, 13:40

Just out of interest, what's the deal with hardened valve seats. Are the seats bought separately, from a specialist or does the machine shop source and fit them. How are they fitted in?

Hat · Mar 1st, 2016, 13:51

The machine shop has them, or sources them, they are an interference fit, by cooling the seats right down they shrink enough to fit in position.

volvogv · Mar 2nd, 2016, 03:35

Back in the olden days when petrol had lead, the deposits would cushion the hammering of the valves. Thanks to clean air laws, lead was eliminated back in the 1970s. Without the lead cushion, the extreme heat and the constant pounding would basically crush the cast iron valve seats especially the exhaust ports.

The solution is to have a machinist cut out the old seats and press in new ones made of hardened steel. I just had this done. Some will say that valve seat recession is a myth but I assure you it is not! Mine were so bad that the #4 cylinder could no longer hold pressure.

Mar 1st, 2016, 13:40	#1
arcturus arcturus Last Online: Today 08:14 Join Date: Mar 2006 Location: Sagres Portugal	hardened valve seats. Just out of interest, what's the deal with hardened valve seats. Are the seats bought separately, from a specialist or does the machine shop source and fit them. How are they fitted in? __________________ life's too short to drink bad wine

Mar 1st, 2016, 13:51	#2
Hat Senior Member Last Online: Feb 18th, 2017 15:16 Join Date: Mar 2014 Location: essex	The machine shop has them, or sources them, they are an interference fit, by cooling the seats right down they shrink enough to fit in position.

Mar 2nd, 2016, 03:35	#3
volvogv Master Member Last Online: Aug 29th, 2016 19:28 Join Date: Oct 2013 Location: Seattle	Back in the olden days when petrol had lead, the deposits would cushion the hammering of the valves. Thanks to clean air laws, lead was eliminated back in the 1970s. Without the lead cushion, the extreme heat and the constant pounding would basically crush the cast iron valve seats especially the exhaust ports. The solution is to have a machinist cut out the old seats and press in new ones made of hardened steel. I just had this done. Some will say that valve seat recession is a myth but I assure you it is not! Mine were so bad that the #4 cylinder could no longer hold pressure.

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