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Hi all, I've been prepping my heads and started lapping the valves/seats.
Ive done 3 so far and the last 2 look great. The first one, however, has grooves going around the seat. The valve has one small groove that is almost gone.
On the other hand, on the seat, im having a very hard time removing them.
What i did different on the first one is i started with 180 grit opposed to the 280 grit i used to start the 2 other valves.
I then go 400 and then 600.
I think i started to coarse on the first valve.
Is it ok to keep lapping till they are gone? Should i keep going with 180? I also have some 220.
Lapping is ok for a final check after a real valve job. But with a "lap job" your seats are going to end up too wide which will hurt performance and sealing by not have enough pressure to keep carbon cleaned off. I am rebuilding a set of heads and that is one part I will be paying a machine shop to do. Also a good valve job starts with good valve guides. Hope that helps.
STOP!!!!!!!!! Those sealing surfaces are too wide on the seats right now. As Metal Chipper says, " Lapping is ok for a final check after a real valve job. But with a "lap job" your seats are going to end up too wide which will hurt performance and sealing by not have enough pressure to keep carbon cleaned off. I am rebuilding a set of heads and that is one part I will be paying a machine shop to do. Also a good valve job starts with good valve guides". Bring those heads to a decent shop before you ruin them. .
The intake valves snd seats are turning out perfect. The exhaust valves and seats are a little more rough.
Should i be scared to keep trying?? Im putting about 10 lbs pressure on the stick and every stroke is at least a 360 turn. I do it till the sound gets smoother then lift and turn 180 degrees and start over again. I do that 4 times then take everything out, clean, inspect and reapply compound on valve seat and some oil on valve stem and continue.
Does this seam right? The seats look great before lapping but they are shinny...
No the seats looked good before lapping. Before lapping them, while cleaning the heads in my varsol tank, i did hand brush them (the seats) with a brass tooth brush. They looked really good and even. Just a little shinny tho.
This is the first exhaust valve. I re did it with 600 grit only. Took s long time and this is as good as its gonna get. Decided to stop as i think im widening the seats.
This is what the first cylinder looks like on the drivers head. Much better results!!
I went straight to 600 grit and cleaned both valves and seats with brake cleaner after each pass.
This is one pass:
Spray some brake cleaner in the guide , pass a 9mm tube brush, spray again, pass the brush again, spray again with brake cleaner and blow it out with air.
clean the valve, coat the valve with the compound, squirt a little oil on the stem, slide in the valve, then rub with the stick till the sound gets smooth and then some, then lift, turn 180 degrees then put it down and repeat. Every 5 times of that, i take out the valve and clean with brake cleaner and inspect.
Took about 6 times that procedure and these are the results
06-05-2019, 09:53 PM
Lapping Valves DIY 
#862 or #706? 
