1FZ Valve Lapping woes. Went too far? How bad did I screw the pooch?

[Wompom]

Been building a brand new shortblock and head.
Last night after a few #6s I was lapping in the first exhaust valve.
was going slow, and nothing, nothing, nothing, almost 2mm.
This is a brand new head, turbo going on it. What would you do?
I'm at about 1.8mm of valve face touching.

 

[Wompom]

Exhaust 11 and 12. 11 is in "spec" at 1.3mm

Overreacting and its fine? Or I biffed a fresh head and should put a new seat in it?

 

[DIRTBIKEUSA]

I would take the measurement again after you have taken a break. How long did you lap it for? Yeah 1.8 seems excessive but maybe you are over looking something.

The book says replace the out of spec valve not the valve seats. Seems like valve is suspect not your new head..

 

[Wompom]

I would take the measurement again after you have taken a break. How long did you lap it for? Yeah 1.8 seems excessive but maybe you are over looking something.

The book says replace the out of spec valve not the valve seats. Seems like valve is suspect not your new head..

Yeah this is today’s review after a good sleep ha.

Apparently too long. First ones I’ve done in a long time and it wasn’t giving me the tone change til this far in, resulting in the over width. I’m planning to replace the valve but real curious since I lapped the seat equally if it will accept a new valve lapped into it and meet spec.
Did the next 5 in spec no issue.

 

[audi2nr]

I hope my eyes are just playing with me but that spot on the valve looks a little strange. Like it got lapped way too much. It looks like an angle you'd see if valve got beat into the seat. Do you have unlapped valves to compare it to? 2nd thought.. what head gasket are you using? MLS? I had my new head and old block and timing cover milled to a surface suited for the mls. I guess it's too late at this point for you though if you are trying to wrap up by next month though.

 

[NKP Garage]

Fingers crossed, hoping you're able to get it straight with just a new valve.

 

[Wompom]

View attachment 3633708
I hope my eyes are just playing with me but that spot on the valve looks a little strange. Like it got lapped way too much. It looks like an angle you'd see if valve got beat into the seat. Do you have unlapped valves to compare it to? 2nd thought.. what head gasket are you using? MLS? I had my new head and old block and timing cover milled to a surface suited for the mls. I guess it's too late at this point for you though if you are trying to wrap up by next month though.

I talked to cometic and they said a fresh block and head from Toyota shouldn’t need to be milled for a good seal.
I do have other new valves. I think I’m going to try and lap a fresh valve in and see what it does. Worst case I’m out a valve and need to have a fresh seat put in.
Best case it’ll lap in to spec

 

[flintknapper]

I lapped my old head at 316K miles after cleaning it up and checking for straightness.

Just lapped them in until I got a concentric ring on the seats and stopped. Its been running fine (I'm 350K now). Didn't even have the valves ground.

Pretty sure you'll be fine. I WOULD replace the valve you're having trouble with.

I understand with NEW parts your desire to get it 'right' and I would too, but you haven't 'screwed the pooch' if you are a little off. These are very forgiving engines.

 

[fjbj40]

Was that valve ground before you lapped?

 

[Wompom]

Was that valve ground before you lapped?

No. Was brand new from Toyota.

 

[fjbj40]

No. Was brand new from Toyota.

Wow, one pic shows quite the groove.

What grit compound you using? Lapping should only take 10 seconds by hand if both surfaces were machined correctly and using fine grit compound.

 

[Wompom]

Wow, one pic shows quite the groove.

What grit compound you using? Lapping should only take 10 seconds by hand if both surfaces were machined correctly and using fine grit compound.

The permatex stuff was all I had on hand.
Was definitely my mistake and went too far but it seemed like the valve had a weird grind pattern when I lapped.
Either way, I’m trying to decide to lap a new valve into that same seat which the s***ty one above was already lapped into, or if I should go have it recut/or the seat replaced.

 

[fjbj40]

The permatex stuff was all I had on hand.
Was definitely my mistake and went too far but it seemed like the valve had a weird grind pattern when I lapped.
Either way, I’m trying to decide to lap a new valve into that same seat which the s***ty one above was already lapped into, or if I should go have it recut/or the seat replaced.

Get the valve refaced, but if the valve is not expensive then it’s a wash

 

[DIRTBIKEUSA]

The permatex stuff was all I had on hand.
Was definitely my mistake and went too far but it seemed like the valve had a weird grind pattern when I lapped.
Either way, I’m trying to decide to lap a new valve into that same seat which the s***ty one above was already lapped into, or if I should go have it recut/or the seat replaced.

Excellent point!

New head, new valve= fine compound.

Used head, used valve= medium/course compound. Of course used stuff need to be in spec before lapping..

Kind of an art form with delicate touch and a sharp eye.

 

[Wompom]

Get the valve refaced, but if the valve is not expensive then it’s a wash

I’m going to get a new valve and then see if I can have the seat recut to start over fresh. Dumb dumb dumb mistake.

 

[flintknapper]

I’m going to get a new valve and then see if I can have the seat recut to start over fresh. Dumb dumb dumb mistake.

If you re-cut the seat you may have to 'tip' the new valve to account for the greater depth (effectively longer length of valve stem). I'd start with a new valve and VERY lightly lap it in. IMO you are fretting over a few thousandths of an inch that aren't going to make any practical difference.

IF you are looking for 'perfection' at this point...then a new seat and valve are the only way to get there (and maintain consistent dimensions across the board).

 

[DIRTBIKEUSA]

Valve seats are very hard. I doubt much material was removed from your small mistake.

 

[fjbj40]

As stated, leave the seat alone, it’s much harder and should be fine. The valve gets lapped to the seat, not the other way.

 

[use2bn83]

Are you blueing up the valve face and tapping it against the seat without rotating it? It looks like the part you are measuring is the portion that’s been lapped against the seat….. the lapping compound will make the contact zone look wider and the margins look thinner than they really are. You should use dykem or Prussian blue for this and not rotate the valve.

 

[DIRTBIKEUSA]

Are you blueing up the valve face and tapping it against the seat without rotating it? It looks like the part you are measuring is the portion that’s been lapped against the seat….. the lapping compound will make the contact zone look wider and the margins look thinner than they really are. You should use dykem or Prussian blue for this and not rotate the valve.

I hope OP has made some progress on his project..