[IdahoDoug]

I'm going to be using the original head bolts as this is a non turbo and will have zero performance mods. I've got two engines worth of head bolts and was able to choose only the ones that were perfect. I will commit to a head retorque, however, just as a data point and to satisfy my curiosity. I've cleaned the threads in the block and they all felt good and looked good. 72 lbs ft of torque and lightly oiled threads with 30wt.

So, the cam cleanup paid dividends and reassured me that on the first go around I did not take off material beyond what was absolutely needed, as two needed a bit of a touch. The journal caps were so chowed. I used a perfect size tube with 1200 grit wrapped around it to knock off the high points of the damage, guided by the blue dye as to when to quit. Then a dremel with a 400 grit scotchbrite like pad for a very light touch to radially clean out the grooves. This allowed me to see a half dozen additional embedded tiny flakes of harder metal which I popped out with a dental pick. Finally, again with a very light touch I did 45 degree cross hatching to help with oil retention.

Goal was to keep material removal to an absolute minimum, while making the cam/journal surfaces more friendly to maintaining an oil film, while knocking off the high spots.

After that, I lined them up, shook my head that anything that bad can go back in a motor and survive, and mentally moved on to the valves.... Here's a picture of the caps now:

As I type this, the valves are sitting in Berrymans to dissolve the carbon, and the head is slathered with oven cleaner, and strapped to a hitch carrier in my LandCruiser. In an hour, I'll sneak over to the hand spray car wash place and pressure wash the thing and see if it gets the job done. Worked well on the combustion chamber side, this time I've filled the ports and the valve guide area.

 

[figgie]

@IdahoDoug

on the head bolts, i would measure their stretch if you have not. Incase someone torque those bolts down to say 90lbs-ft which is way beyond their plastic region.

 

[IdahoDoug]

Is there a spec for that? On my LandCruiser there was a thickness and length spec for the head bolts in the factory manual. I didn't see one in the Supra's factory manual...? Thanks.

So lesson learned on the Berrymans. It sat all night and only "affected" the carbon on the valves. I left a message on their website asking if it works in a cold garage. Then this morning found the answer on the can after it did not perform. Above 70. So it's now in the shop sink in the house. Happy it has no smell.

The foray to the car wash with a head full of oven cleaner worked out.

 

[figgie]

nice and clean. Are you getting the head machined? Those indents around the combustion chambers look pronounced.

 

[IdahoDoug]

I had it checked at a shop and it's flat top and bottom. I gave it a quick whiz with the marble slab I used on the block, just to take the texture off from the head gasket nibs for flatness testing. Not sure if I will try to eliminate those remaining marks or not. After the valve seats cleanup, I will look at them and think again. One thing on my mind there is the head was at a machine shop a few thousand miles before the car ended up in the U pull. I found the bill in the car's glovebox. If it was machined where material was removed, I don't want to add to that if possible. Is there a measurement on the head I can make to see if it's still at stock thickness?

 

[Captain]

Is there a measurement on the head I can make to see if it's still at stock thickness?

Deck to valve cover surface is supposed to be 116mm on an OEM head.

 

[IdahoDoug]

Checking... Yes - 116 though I'm going to check again as I got 115.8 on second measure, but have to run an errand. Thanks for the info.

 

[IdahoDoug]

So the Driftmotion oil line arrived last week. It goes on the oil pump to eliminate the restrictive banjo fitting. Kinda pricy but I think it will help oil arrive faster up in the cams on startup with greater flow in the first few seconds or so before the oil system is pressurized. Looks well made.

 

[IdahoDoug]

Started lapping valves this evening with that Clover Brand valve paste. I started on the exhaust side and finished the 7th one before my arms got tired. If you've ever tried to start a fire using friction and a wood dowel, you'll know how my arms and hands feel right now. This is actually fairly tough. Each valve is requiring 3 sessions to get the seat smoothed and pits removed. Here's a before and after with the before on the right
:

The high tech tool:

 

[Marios90mk3]

will you be using the arp insert for the botl holes in the head?

 

[BoostPsiKPA]

Get a hose. Set the head on the side. Get a drill. Use a long bit in the drill. Use hose on valve stem and spin the valve.

GO SLOW. It will be done much quicker.

 

[IdahoDoug]

Mario - no, I'll be using the original factory bolts and torquing it to 72. I've already cleaned the block threads and they looked great from the beginning. I have a tap as well, but saw no need to use it. I also have a #10 head casting and it looks to be in good shape.

Since there has been so much discussion of the 7M head issues, it's a good time to also mention I'm using a run of the mill aftermarket conventional head gasket whose construction appears in line with a factory gasket in terms of size and orientation of the metal reinforcements, etc.

This is a good time for a question, though. Somewhere (not in the FSM) there is a 7M instruction on head bolt washers to have the "bevel" in a certain direction. I cannot find it now, but my factory washers have a bevel on the inside hole on each side. Which makes me wonder if folks have an opinion here. The washers on one side have a slight lip from when they were formed. I plan to lap them perfectly flat.

As to the drill. I'm concerned about a couple opinions expressed in my research that the radial grooves formed by continuous rotation of the valve paste grit are not a good idea. It's lots of back and forth tiny grooves that stop that are a better metal to metal surface. So I'm good with the pace and I have already found stopping 3 times for new polishing paste lets me watch the changes and stop right when I'm happy.

So, I have also formed some input on the "head crushing" issue and will share it in a separate thread as it will be generating some discussion. Stay tuned. May get to a few tonight!

 

[Piratetip]

Lapping looks excellent!

Depending on how much it takes off, you will probably have to adjust all the valve shims to get it back into spec.
Though I expect you already have this on your list of to-do's when you get to that point.

 

[IdahoDoug]

Thank you! Yeah, I'm expecting to need a full valve adjustment and hoping to go with tipping the valves. Owing to the precision needed here to avoid needing shims, I'll mark each valve and bring them to a shop to have the requisite few thousandths knocked off. Yes, this would be so much easier if it had the screw adjusters like my Vanagon does. That thing takes like 15 minutes to adjust the valves, and to add insult to the short time required, VW engineers even did a "show off" move. The valve covers are held on by wire bails that you literally grab and swivel out of the way and the valve cover is in your hand in 4 seconds. Meaning the adjusters are now right in front of you to slap tools on. OTOH, that engine only puts out 92 hp with 2.1 liters so there is no comparison to the Supra's 200hp with 3.0 liters...

If anyone's come up with a masterful way to do this at home, I'm all ears....

 

[IdahoDoug]

Alrighty then. A few weeks ago I left for vacation with 7 of 24 valves lapped and I'm back home. Oh boy am I glad I did the exhaust valves first. These were pitted enough I needed to repeat the process with fresh compound 3 times each. Finished exhaust side this afternoon, then switched. The intake valves were much easier, requiring 1/4 of the time and only 1 cycle of compound. I think they're not as hardened as the exhaust seats. Maybe an hour to do all intakes, vs about 4 hours for the exhaust side. I just finished the last one and they all look great.

Tips for anyone who does this:

Lapping is easier if you are reaching over the head to do the far side and they're tilted toward you as if looking down the valve guide straight at your eyes.
Use a damp paper towel in a bowl to clean the lapping tool on when you get some grit on it.
Wipe the valve stem between each lapping session and you'll find grit. No matter how careful you are.
Use a bright work light, plus have a bright head lamp as you'll be making judgement calls when to stop that require fine details that are disappearing from the work surface.
Use one paper towel to wipe the stems and one to wipe the grit off the valve and valve seat. Swap the stem towel to become a grit towel and start a fresh one on the stem wiping.
Be sure to number the valves with a sharpie. Very bad idea to mix them up.

So next I need to decide if I'm going to port and polish a bit. It actually looks like a serious pain in the butt to work around the valve guide from the valve seat side. Not a lot of room for a burr type tool in there and it will be very tedious. Sure, looks easy from the manifold end but no sense in improving flow in one without dealing with the other. So, still thinking... Anyone done this themself? Tool suggestions?

I've got to use a dental pick to clean some carbon just behind the valve seats, so will be dealing with that. In the meantime, my tool to adjust the valves arrived while we were gone. Its a pliers like affair to compress the valve spring with the cam on, and a device to hold it while you pull the shim out and replace it.

So, back in the saddle here!

 

[Captain]

So next I need to decide if I'm going to port and polish a bit.

On a stock motor there really isn't much to gain in the ports themselves. Most of the gains will come from reshaping the chambers, which will result in a lower compression ratio. So without custom pistons to account for that change it'll do more harm than good. FWIW, I've made 580whp on a stock head (valves, ports, and CCs) with some 272 cams and upgraded springs.

Anyone done this themself? Tool suggestions?

Yes, and as you said, tedious. I'd recommend a good, high quality single cut burr with a tool that has an adjustable speed. Ports tend to come out a bit better if you use the biggest burr you can get; they tend to help get the cut radius consistent.

 

[figgie]

Yes, and as you said, tedious. I'd recommend a good, high quality single cut burr with a tool that has an adjustable speed. Ports tend to come out a bit better if you use the biggest burr you can get; they tend to help get the cut radius consistent.

@IdahoDoug
just be careful with the port divider as too much material removal from there exposes the water passages behind that. area

 

[IdahoDoug]

Hmm. OK, done with that thought process. Figgie's got me worried about things I could screw up, and Captain's got a good point on the cylinder compression chambers. Every cubic MM I remove there lowers the compression ratio and where it would give back is likely going to be at higher flow rates/high RPMs. Where I won't be driving it. Tx.

 

[figgie]

Hmm. OK, done with that thought process. Figgie's got me worried about things I could screw up, and Captain's got a good point on the cylinder compression chambers. Every cubic MM I remove there lowers the compression ratio and where it would give back is likely going to be at higher flow rates/high RPMs. Where I won't be driving it. Tx.

I am terribly sorry. I did not mean to get you worried on something like that. It is like everything else, it can be done but one just cant go to crazy especially in that area.

btw i was looking at your older pictures of the head

#3 cylinder looks like it was detonating as the pitting on the exhaust side and some on the intake side prior to you lapping the head. Are you reusing the fuel injectors?

 

[IdahoDoug]

Wups, thought I posted this last eve. It was sitting ready for me to push the button. So two quick posts from me:

And then there is this, compliments of Hot Rod Magazine online:

Flow Surface Texturing
We decided to include a few thoughts on this subject, even though there may be some skeptics about the value of working certain flow surfaces in an intake manifold. Actually, the concept can be carried out beyond the intake manifold to such places as piston tops and combustion chamber walls. When properly applied, the notion is to provide some boundary layer excitation, especially in locations where air and fuel tend to separate. By so doing, some of the separated fuel becomes re-suspended in the inlet air stream. We know for a fact that this technique is particularly beneficial when also applied to piston crowns and certain areas of the combustion chamber.
Inside the intake manifold, roughening the entire length of the runners (at least to the extent surfaces can be reached), plenum floors and around the entries to the runners can help, depending upon the fundamental design of the manifold. You'll be able to read the effects by slightly reduced b.s.f.c. data. The best barometer is on-track performance because some of the benefits show up only in a transient mode of operation, as provided on the track.

So, I may clean up some of the connections of the manifolds but not go into them to knock down texture. Toyota actually put very uniform texture throughout my head intake ports. I read the entire article and on curves of intake air flow, the heavier fuel droplets can't turn as sharply as the air, and end up against the intake wall on the outside of the turn where they are no longer atomized. A smooth side keeps a layer of fuel flowing down it as it sticks to the wall (bad). A rough texture causes the fuel to be picked back up and reatomized (good) as the fuel flows up and down the texture. Interesting, eh?