Valve Lapping
01-28-2019, 07:33 AM
#11
Platinum Member
Join Date: 12-06-2009
Location: Alabama
Posts: 11,098
I have my 2.0 LNF cylinder head apart to replace the valve seals. I'm not planning to grind the valves since I'm also not planning to replace pistons, liners, and rings (I.e., I don't want to freshen up the top-end, to then create excessive blow-by on the bottom end). But I was thinking of lapping the valves at least. I've done this on plenty of other engines in the past, but is there any reason I should not do this on the LNF? In other words, is there any weird nuance about the engine/head that prohibits or discourages valve lapping?
Thanks in advance
M Ridzon
Thanks in advance
M Ridzon
01-28-2019, 07:38 AM
#12
Senior Member
Thread Starter
Join Date: 01-16-2017
Location: Ohio
Posts: 362
Yup!
The valve and head are not "toast" currently. So perhaps lapping may not increase compression that much. I removed the valves a few days ago, but I can re-install them to do this test w/washer fluid. Why washer fluid? Because it's benign and because water will lead to rust on the steel valves? Also note...the combustion chambers have holes for the injectors, which are removed. So I cannot completely fill them with fluid (for obvious reasons); I can probably fill them about 80% for the test.
Yes, seals will be replaced. I'm not sure if you saw my recent mishap or not. But you can read here about how every shred of rubber and plastic came under attack in my engine due to contaminated oil during walnut blasting.
Level the head and fill the chambers with washer fluid and measure how fast it leaks, draining the combustion chamber, past the valve seats. Lap the valves and do it a second time. Tell us what you for found. Lapping the valves isn't going to raise the compression ratio that much, if any. Unless those valve seats and valves were toast to begin with.
Last edited by m_ridzon; 01-28-2019 at 08:20 AM.
01-29-2019, 07:36 AM
#13
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Thread Starter
Join Date: 01-16-2017
Location: Ohio
Posts: 362
My plan is to merely wipe the valves and seats with a rag and re-assemble them into the head, not having lapped them or scrubbed the sealing faces. I'll install the spark plugs and plug the injector ports with some silly putty. I'll then invert the head and do this liquid test. My questions:
- What's unique about using "washer fluid?" (versus some other liquid)
- Assuming some leakage may happen, what exactly am I looking for? A certain "rate of leakage?" (chambers empty themselves over X seconds?)
01-29-2019, 08:22 AM
#15
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Location: Lake Ronkonkoma, N.Y.
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01-29-2019, 12:35 PM
#19
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Join Date: 08-03-2010
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