How To - Valve grinding

[BLUE]

09/28/14

This is a "How to - Lap your valves" general guide tutorial.
You can do this process yourself or take it down to an automotive machine shop to have them do it for you.

Materials needed.
* a LOOSE Cylinder head to be worked on.
* Valve Spring Compressor.
* Valve grinding compound.
* Valve grinding tools.
* Extendable small magnet.
* Wet damp lint free cloth... a few of these at least is a good idea.
* Repair manual (trusted).
* A few containers or a large container that is numbered to keep all valve components in order/numbered #.
* and... common sense.

NOTE: In earlier heads with softer seats you're going to want to check your valve to rocker clearances (example meaning: --the maximum clearance when the lifter head is spun down all the way into the head) to see if the valve face/and/or seat are severely worn. If they are it's entirely possibly to grind valves on a current head into softer seats/worn parts to allow NO adjustment or slack (which is needed) when you're done. This especially apply's to "new to you" heads that have never been run. Later cylinder heads such as this 1981 280zx P79 OHC aluminum cylinder head had harder seats , and better valves.

We are working on an already loose from the engine cylinder head.

(STEP 1) --- Break loose the 19mm bolt at the front of the camshaft , but do not remove quite yet (if you have an impact wrench or gun you can do this step later). Remove the rocker retainer springs on all rockers , and set aside in order. Go ahead , and break loose the adjustment on the lifters with a 14mm , and 17mm wrench. Next spin the clock-wise so that the lifters head goes downward into the cylinder head. Spin the cam carefully while noting which lobes are point ^ upwards. These are the ones you want to remove the rockers from first. Place them carefully in order on the exact position in which they came off the head along with a note/holder. Do the same for all cylinder head parts related.

(STEP 2) --- Pull out or remove the camshaft. You cam either un-bolt the retainer at the front with a 19mm impact wrench + 10mm wrench. Some people chose to remove the cam towers , and lift the cam-shaft/towers off directly (as the camshaft towers are aligned with hollow dowels for re-placement). I choose to pull the camshaft out the front this particular time. Another time I pulled the camshaft towers with the camshaft. Carefully and slowly supporting it evenly throughout the process with plenty of lube if pulling only the camshaft.

017 by 71240z, on Flickr

002 by 71240z, on Flickr

Camshaft is out.
010 by 71240z, on Flickr

(STEP 3) --- Optional. I taped up the cam towers to keep grit/crap/debris from getting in while the head was apart. There are (2) main oil gallery holes feeding all the towers on the bottom that received some green tape. Also non-related is I removed the lifters from this head to switch them with another set. Not required for lapping valves.

008 by 71240z, on Flickr

(STEP 4) --- Grab your valve spring compressor. Mine looks like a big "C" design. Yours maybe an overhead or leverage of some type design. Grab your extendable magnet as well (for extracting the valve keepers once the valve springs are compressed.)

001 by 71240z, on Flickr

[BLUE]

(STEP 5) --- Position your valve spring compressor directly on the center of the valve face (pointy part on the bottom for me) , and the "U" shaped part at the top of the valve spring. Commence to compress slowly , and carefully watching to make sure you are on center all the time ... slowly. Keep your hands on the head/tool at all times , and at least some light pressure. If done correctly , and carefully the below is the results.

023 by 71240z, on Flickr

(The center 2 things on the valve stem are the valve stem keepers which will need to be extracted. They keep the springs in "place" from flying off. Notice that they are tapered skinny at the bottom , and fatter at the top. Act as a "wedge" so to speak in the retainer.)

021 by 71240z, on Flickr

(STEP 6) --- Pickup your magnet , and extract the valve keepers one by one. Place them , as well as all valve-train components in order to the position they were extracted from. The rockers/lifters are more critical than the springs/valves. That is IF the valves are all in good shape. As you pull the valves out themselves make sure you check the fitment of the guides (how tight or if pretty loose) , and if any of them stick... I've had a couple of exhaust/intake valves stick. Make sure to inspect the sealing face for pitting or cupping ... both "can" cause a loss of compression or pressure. Lots of factors depend.

014 by 71240z, on Flickr

Items placed into the container , and labeled on a piece of paper what goes where (key).
*Valves
*Valve retainers
*Springs
*Keepers
*Rockers
*Rocker retaining springs
*Valve spring shims
*Etc
030 by 71240z, on Flickr

(STEP 7) --- Before grinding any valves you want to make sure they're CLEAN. You can do this by either buying new Valves all together , blasting them , or wire wheeling the faces/heads of where any/all carbon/soot/fouling/debris exists. Pretty important that it's done or at least attempted to as much as able.

017 by 71240z, on Flickr

[BLUE]

(STEP 8) --- Wet a couple of lint free cloths with some water on one side , and dry on the other. Make ready. Pickup the valve grinding compound , and open it.

039 by 71240z, on Flickr

(STEP 9) --- Pickup desired valve to be lapped (grounded). In this case we're using an Intake valve.

040 by 71240z, on Flickr

(STEP 10) --- Grab your Valve grinding/lapping tool (looks like it has suction cups on both ends). Make sure it has a touch of moisture for the suction to grasp. Press the face of the tool evenly overall with the diameter of the valve like the picture below. Add some valve grinding paste to the sealing face of the valve (that goes against the valve seat in the cylinder head)

041 by 71240z, on Flickr

Example = Like so in picture below (a bit much compound but it is ok since water based).
042 by 71240z, on Flickr

(STEP 11) ---- Carefully guide the valve into the valve guide making sure NOT to get any compound into the soft valve guide itself or the ports if can helped. Remember you don't need much compound at all , and more can ALWAYS be added later !

044 by 71240z, on Flickr

(STEP 12) ---- Press valve firmly against valve seat using the valve lapping tool while twisting your hands like you wish to start a fire ( as in rolling the tool between the palms of your hands while applying pressure. This maybe best accomplished with the cylinder head-to-block surface facing ^ upwards ). Only do a few strokes before pulling out the valve to check the face , and valve seat. You don't want to go to far or lap to far !!! (it's very possible especially with softer valve seats that haven't been replaced yet for certain years).

045 by 71240z, on Flickr

(STEP 13) --- Pull out your valve ... check the valve seat face for progress , pitting , erosion , etc ... check the valve face for the same.

[BLUE]

(STEP 13) --- Pull out your valve ... check the valve seat face for progress , pitting , erosion , etc ... check the valve face for the same. The valve in the picture below is done to my satisfaction. I have hardened valve seats in this particular head as well.

The valve seat looks good.
047 by 71240z, on Flickr

049 by 71240z, on Flickr

^^^ Now that both valve seat , and valve are satisfactorily completed the compound can be cleaned off.
Grab your water wet cloth , and carefully wipe every last grain of compound out of the cylinder head.
Triple check to make sure it's all gone.

(STEP 14) --- ^^^ Now that both valve seat , and valve are satisfactorily completed the compound can be cleaned off.
Grab your water wet cloth , and carefully wipe every last grain of compound out of the cylinder head.
Triple check to make sure it's all gone.

050 by 71240z, on Flickr

052 by 71240z, on Flickr

053 by 71240z, on Flickr

(STEP 15) --- NOTE: Be very careful how much you actually lap/grind a valve. The process does , and will change valve clearance as well as very slightly the geometry depending. It's perfectly safe to do so as long as you apply some common sense .

(STEP 16) --- Assembly is revere of removal. Just keep the rockers/lifters/lash pads in order if nothing else. Take pictures. Label your stuff. Leave it in an un-disturbed area , and you'll be fine. Have fun !!!

BIG NOTE: The cam tower bolts are absolutely no more than 12ft lbs !!! I put mine at about 10ft lbs for sake of in-accurate torque-gauge or wrench. If you have issues putting the rockers back in (tight clearances) simply compress the valve spring downwards (or actuate it like an engine) , and slip the rocker in. Make absolute sure you have plenty of room for adjustment as there needs to be some !!


This head is practically done ready to be assembled at this point !
059 by 71240z, on Flickr

[Laecaon]

My friend was insistent that we did this on his motor. I didn't have a suction device like yours, so I just chucked the end of the valve stem in my drill. Pulled up a bit on the drill, ran it at low speeds forwards and reverse. High speeds wouldn't work anyways as it just flings the compound off. Just went until I could see a consistent ring where the compound actually did something.

[DRIVEN]

Great writeup! I've used both methods with good results.

On a side note; This may not be a viable option on some earlier engines or high milers. I know that at least on earlier A-series the seats were somewhat soft. Once they get pounded out you will either need a cutter to narrow up the margins or the seats may need to be replaced altogether. Later heads may have hardened seats so it's not such an issue.

Another side note; If you find that your head is worn beyond the limits of a home refresh, I've had nothing but good experiences with Central Cylinder head in SE Portland. Allen does great work and is reasonable on pricing. I've never left there feeling like I was sold more services than I needed.

[Ni10]

how did you get the cam towers in line ( straight ) for the cam ? I've read if there not perfectly in line that the cam will break at high speeds.

[Laecaon]

how did you get the cam towers in line ( straight ) for the cam ? I've read if there not perfectly in line that the cam will break at high speeds.

I have removed the towers on 3 different heads that went onto running motors. I havent seen an issue yet... I have a tendency to install them with the cam though...

[Ni10]

how did you get the cam towers in line ( straight ) for the cam ? I've read if there not perfectly in line that the cam will break at high speeds.

I have removed the towers on 3 different heads that went onto running motors. I haven't seen an issue yet... I have a tendency to install them with the cam though...

reason I asked, is in-case someone wanted to know. I take it you would turn the cam until you feel the least resistance. Once that's been found, you torque the cam towers down and check. .. right ?

[Laecaon]

No... I just bolt and go. I think its best not to do with a new cam though. Original cams to the head though, whatevers.

[BLUE]

how did you get the cam towers in line ( straight ) for the cam ? I've read if there not perfectly in line that the cam will break at high speeds.

I have removed the towers on 3 different heads that went onto running motors. I haven't seen an issue yet... I have a tendency to install them with the cam though...

reason I asked, is in-case someone wanted to know. I take it you would turn the cam until you feel the least resistance. Once that's been found, you torque the cam towers down and check. .. right ?

That's a good way to do it ( I do that ) , but everyone has their own system as we all know
Yup same here have done it on 2-different Datsuns that are still running around without a worry.

I've ran into some over-heated enough shitty heads , and figured out what I wanted to do with them with a combination of the flat-bar , dialing down the rockers , lubing them up and feeling for resistance. It's safe to say I have one head that probably has never been over-heated (butter butter smooth).
Re-installation I do use a cam , a light mallet , lots of lubrication , torque the towers only very very little (as people strip the shit out of them which if you're reading this is a huge no-no in this part of the head). As long as ALL the head-alignment dowels are present it usually gets relatively close (for future readers). I've had another head where at some point the heads owner/shop virtually removed 70% of the alignment dowels before putting the cam towers back on (I doubt anyone... could get those lined up close again after that). That's another big no-no (for future readers). Cam towers need to be put back exactly where they came off of as well , so label or mark them (future readers). After having your heads milled Cam towers need to be shimmed upwards (future readers). These shims are placed at the base of each cam-tower restoring original height , and valve-train geometry.

Removing the cam-towers for the first time for anyone after reading in the FSM saying not to ever do it can be little nerve wrecking (it was for me definitely).
Then again many shops or machine shops do this without a second though , and sometimes there's no way around it.
There are alignment dowel pins for a reason (comforting I suppose).
I still pull the cams out of the front if I feel it's un-neccessary to pull the towers with , but have no real problem doing it either way.

Use common sense , and when in doubt follow the people that built the machines (even if it goes against what I say).

On another note.... not sure why I showed pulling off the cams/towers in this how-to when I clearly had the valve-springs removed without having to remove the cam