So valve seats cut tooooo deep

[d510addict]

So i recently purchansed a w53 closed chambered head and I have an issue with it. Took it to the machinist to have some work done to it, the valves were plainly sunk realy deep and after some inspection of the head by the machinist it seems the seats were just cut really deep. There is worry that A.) there might be a water issue and B.) if htere isnt one now, there will be if he puts a wider seat it. Currently its being pressure tested and if that goes well he is going to see how 280 valves fit (to see if it raises the valves enough to not need a new seat). My question is other than welding the seat area up and reworking them are new seats my only option? and how deep is too deep? The machinist I am using is certainly no rebello but he has done quit a bit of work on L motors and is very well respected as a great engine builder/machine guy in the area, would he be correct that you can hit water if u cut those seats too deep?

[datzenmike]

Valves can sink just from wear. Eventually you can't set the lash.

 

The head may have been milled incorrectly too much and the new seat is just sitting too deep. Pretty sure a wider valve will need a wider seat.

[d510addict]

What I am trying to ask is will he hit a water jacket if he cuts new seats? They are brand new seats in there and are pushed realy really far into the head its not a milling issue as lash has nothing to do with it, The cam isnt even on. The seats are just too deep.

[datzenmike]

You mean remove the seats that are too deep and re-cut into the head for a wider seat for a wider valve? People do wider seats and valves all the time. Never hear of hitting water jacket.

[d510addict]

Yes i mean that, but holy shit these are really really cut far into the head I wish i had pics.

[datsunaholic]

The seats are cut deep, or the head is cut deep?  The only time the head should be cut is if putting in bigger valves, since you'd need bigger seats.  If the head is cut too deep there's no way to fix that other than weld up the head and cut it for new seats, because even if you took the old seats out, the head is too deep so the new seats would be too deep.

 

If it's the seats cut too deep, which is REALLY easy to do, then the only solution is to replace the seats.

 

 

280 valves won't help if the seats are too deep.  The seats have to match the valves, so if it was using original size valves, the 280 valves will be too big for the seats anyway.

 

 

This ALMOST sounds like someone tried to cut original (smaller) seats for bigger valves.  Doesn't work that way with aluminum heads with inserts.  That's how cast-iron heads are cut for bigger valves, though, since the valve seats ARE the head.  Iron heads didn't have inserts until the late 60s early 70s.  Aluminum ones always did.

[d510addict]

Ok well ill talk to him, its the head that appears to be cut too deep as the seats are brand new looking.

[GreaseMonky]

The seats are cut deep, or the head is cut deep?  The only time the head should be cut is if putting in bigger valves, since you'd need bigger seats.  If the head is cut too deep there's no way to fix that other than weld up the head and cut it for new seats, because even if you took the old seats out, the head is too deep so the new seats would be too deep.

 

If it's the seats cut too deep, which is REALLY easy to do, then the only solution is to replace the seats.

 

 

280 valves won't help if the seats are too deep.  The seats have to match the valves, so if it was using original size valves, the 280 valves will be too big for the seats anyway.

 

 

This ALMOST sounds like someone tried to cut original (smaller) seats for bigger valves.  Doesn't work that way with aluminum heads with inserts.  That's how cast-iron heads are cut for bigger valves, though, since the valve seats ARE the head.  Iron heads didn't have inserts until the late 60s early 70s.  Aluminum ones always did.

 

I have actually had luck cutting smaller seats to fit the larger Z valves on a L head

[I'm BLUE]

I believe there are (2) different lengths of L28E 280z(x) valves as well.

 

I'm sure you know this ... It's something worth looking into/researching... and talking to your machinist .. if you haven't had the chance before making any hasty decisions :)

 

I really don't know if that helps ya though.

 

good luck d510addict

[GreaseMonky]

there is 2 different length, on that is the same as the L series 4's and one that is shorter

[banzai510(hainz)]

its not a milling issue as lash has nothing to do with it,

 

if TOO DEEP you wont be able to adjust the valve lash.as you run out of room on the threads of the threaded post.

 

If one installes longer valves the stems still need to be cut so one lash pad sizes fits across. Or really have it close enough.

 

If this guy knows L motors he should know already. I never heard of hitting the water jacket.

 

why not just put new seats in.???? and hope he does them right as I seen them fall out also not doing them right.

 

 

You could be like other L motor guys and have a couple spare heads on the side not not worry about this.

 

The nissan book has or had 43 mm stainless valves as a option.99996-M1030

[d510addict]

Ive been scouring the planet for a closed chamber head Hainz :) just cant fine an unmolested one, my goal is something good for dd and a bit mroe peppy than stock for harder driving but every head I find has issues. Imma go into the shoppe on Saturday and get picks and talk with him about some things mentioned here. I guess if worse comes to worse I can start scouring for a lz23 motor, I have a head for that but the block I have is in great shape and dont wanna do another swap anytime soon.

[d510addict]

Turns out that the head itself was cut for oversized seats then the seats were cut really really deep for stock valves. A new cut for 280 valves brought the valves up to near perfect depth.