Deacon Blue Posted March 5 Report Posted March 5 I’ve just had new valve guides fitted along with associated valve seat cutting and valve refacing. Do I need to lap the valves in? The machine shop says it isn’t necessary as modern machining methods are so good. Steve Quote
John Morrison Posted March 5 Report Posted March 5 Check by filling the chambers with paraffin and seeing if any leaks out over say an hour John Quote
Deacon Blue Posted March 5 Author Report Posted March 5 15 minutes ago, John Morrison said: Check by filling the chambers with paraffin and seeing if any leaks out over say an hour John Is that with the springs installed? Presumably so as that would be a “real life” situation. Quote
trchris Posted March 5 Report Posted March 5 Hi Steve l would lap the valves, but then I’m old school . Chris Quote
John Morrison Posted March 5 Report Posted March 5 2 hours ago, Deacon Blue said: Is that with the springs installed? Presumably so as that would be a “real life” situation. Just so, and if any cylinder loses paraffin then those valves are not yet sealed, and need lapping. John Quote
Lebro Posted March 5 Report Posted March 5 If they are your original valves, then yes I would lap them in using fine grinding paste, You will see after the 1st attempt whether they are ok by looking at the surface - should be a nice even grey appearance on both valve & seat. Bob Quote
Deacon Blue Posted March 5 Author Report Posted March 5 They are the original valves Bob but they have had the seating area refaced. Steve Quote
Lebro Posted March 5 Report Posted March 5 I still would, just to check, easier to do before reassembly & checking with parafin ! Quote
Deacon Blue Posted March 5 Author Report Posted March 5 5 minutes ago, Lebro said: I still would, just to check, easier to do before reassembly & checking with parafin ! Too late. Just put the springs back on! That old valve spring compressor came in handy. Looks like I’ll be getting the grinding stick out again. Assuming my grinding paste hasn’t dried out! I had the head skimmed 10 thou ( it actually needed that much to get it even). Do I need to get the sharp edge around the combustion chamber taken back a bit? I found a date stamped into the head indicating some work done on it in 1991. I believe it had 20 thou taken off at that time as head now measures 3.30”. Quote
Lebro Posted March 5 Report Posted March 5 Now you have the springs on, just go for the parrafin leak test, if that's ok, then leave it. Yes, I would just take off the sharp edge - no more, especialy around the inlet valve. Bob Quote
Ralph Whitaker Posted March 7 Report Posted March 7 Finding valve grinding paste today is fun. Ralph Quote
stuart Posted March 7 Report Posted March 7 2 hours ago, Ralph Whitaker said: Finding valve grinding paste today is fun. Ralph Not so Grinding paste Stuart. Quote
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