Valve guide insertion
Posted: Tue Apr 16, 2013 10:24 am
I am inserting new valve guides into some T4 2 liter heads. Core drilled the exhaust guides with the help of an angle plate and heated the heads to open up the bores. Punched out the guide remainders and inspected the bores. Little flakey but not too badly scored (long vertical stripes). Made some measurements of the guide bore and the actual diameter of a new valve. Valve stem was in spec. My measurements show an average of about 2 mils difference that I hope is the "crush" number. Seems reasonable for crush. Anyone have a better number? Can't find a factory value. Surely don't want a guide to slip out under operating conditions.
Also concerned about the slop/rock of a valve head as specified by Bentley. Bentley says you are OK (new) with a slop/rock value on an exhaust of 14 mils. That's a pretty big number considering the guide to stem is only from about 1.7 to 2,5 mils. I know the throw length test is long but that's still a lot of rock for new parts. Thoughts? Going to try to get some "dry ice" and will heat the heads to ease the insertion (wish I was back in the lab to steal some LN2). Bob L.
Also concerned about the slop/rock of a valve head as specified by Bentley. Bentley says you are OK (new) with a slop/rock value on an exhaust of 14 mils. That's a pretty big number considering the guide to stem is only from about 1.7 to 2,5 mils. I know the throw length test is long but that's still a lot of rock for new parts. Thoughts? Going to try to get some "dry ice" and will heat the heads to ease the insertion (wish I was back in the lab to steal some LN2). Bob L.