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What Happens to a head in a machine shop
144 Attachment(s)
What Happens to a head in a machine shop
First Not all shops have the same equipment and the procedures from one shop to the next can and will differ. Some shops cater to domestics and others imports or even diesels. Some shops will view everything as a “stock” rebuilds. So…. The most important thing to know is the shop you use and the equipment they will use. The subject head is a Mitsubishi 4G63 7 Bolt The first thing that should happen is the machinist looks at the head. Checking for the obvious damage, broken bolts, stripped bolt holes, bent valves, ect. https://www.miataturbo.net/attachmen...ine=1337812162 At this point it is up to you as the customer, inform the shop what you want done, such as… 1) Pressure test for cracks 2) Valve job 3) Surface 4) Guide work 5) Any performance work wanted Also now is the time to speak about who will provide what parts, valves, seals, guides, springs, ect. Now the shop should be able to give you, the customer, an approximate estimate of what the parts and labor will cost. You as the customer have the choice to agree, or go somewhere else. Now that your head is at the machine shop, and you have agreed to have the work done. The first thing to happen is the head will be disassembled. The tools needed are https://www.miataturbo.net/attachmen...ine=1337812162 Wire basket for small parts springs, valves, ect Small container for valve locks Valve lock release tool (socket method) Hammer 10mm socket 12mm socket 12mm socket Ratchet 5.5mm allen bit socket or wrench Pocket magnet Long reach needle nose pliers w/45* bend Impact gun (not pictured) Cam gears come off first, use impact with the 17mm socket https://www.miataturbo.net/attachmen...ine=1337812162 Next remove the cam tower caps, use impact or ratchet w/12mm socket. Start at the ends working towards the center https://www.miataturbo.net/attachmen...ine=1337812162 https://www.miataturbo.net/attachmen...ine=1337812162 Once the cam caps are removed, lift the cams out. https://www.miataturbo.net/attachmen...ine=1337812162 Next lift the roller followers out https://www.miataturbo.net/attachmen...ine=1337812162 Now you can remove the HLA’s https://www.miataturbo.net/attachmen...ine=1337812162 https://www.miataturbo.net/attachmen...ine=1337812162 Now remove the oil spliter https://www.miataturbo.net/attachmen...ine=1337812162 Now remove any other small bolts https://www.miataturbo.net/attachmen...ine=1337812162 This is a “heat tab” Most machine shops use them. The center will slide down at 240-250* and totally dissolve at 260* https://www.miataturbo.net/attachmen...ine=1337812162 Next is to remove the valve train. Yes the same method that a lot of DIY people use are used in a machine shop. Use a basket and a paint cap, have a pocket magnet handy too. https://www.miataturbo.net/attachmen...ine=1337812162 Have your “tool” and hammer ready to go Place the tool on the spring retainer and give it a firm whack. The locks will stay in the tool and release the retainer and spring. Place the retainers and spring in the basket https://www.miataturbo.net/attachmen...ine=1337812162 Fish the valve locks out of the head casting with the pocket magnet. https://www.miataturbo.net/attachmen...ine=1337812162 Place the valve locks in the paint can cap. https://www.miataturbo.net/attachmen...ine=1337812162 Now remove the spring seats with the pocket magnet and place in the spring basket to be cleaned. https://www.miataturbo.net/attachmen...ine=1337812162 Next roll the head over and remove the valves and place in the basket. https://www.miataturbo.net/attachmen...ine=1337812162 This head was rebuilt once before, it must have had bent valves.So I will change the valve guides. Now roll the head back over and remove the valve stem seals, throw these in the trash. https://www.miataturbo.net/attachmen...ine=1337812162 Next grab the 5mm allen bit and remove all the oil galley plugs. Keep these to be installed later, place in the paint cap with the valve locks. https://www.miataturbo.net/attachmen...ine=1337812162 The last thing done is to remove the cracked valve guides. https://www.miataturbo.net/attachmen...ine=1337812162 Now that the head is fully stripped, it can be tech’ed First thing is to do a quick clean on the head gasket surface. https://www.miataturbo.net/attachmen...ine=1337812162 Next is to measure head thickness. https://www.miataturbo.net/attachmen...ine=1337812162 Now to check to see how bad the head is warped. https://www.miataturbo.net/attachmen...ine=1337812162 Notes are taken to reference back too. https://www.miataturbo.net/attachmen...ine=1337812162 If it all checks out, it goes to cleaning. It gets thermal cleaning, then glass beaded. https://www.miataturbo.net/attachmen...ine=1337812162 Next oil port mod #1 is done https://www.miataturbo.net/attachmen...ine=1337812162 Next all the oil galleys get gun brushed https://www.miataturbo.net/attachmen...ine=1337812162 Now the entire head will be blown off with compressed air, including every bolt hole to make sure there is no glass bead media is left in or on the casting. https://www.miataturbo.net/attachmen...ine=1337812162 next is a coat of spray paint to seal the casting. https://www.miataturbo.net/attachmen...ine=1337812162 Now new guides can be installed. https://www.miataturbo.net/attachmen...ine=1337812162 They are set to height. https://www.miataturbo.net/attachmen...ine=1337812162 Now the valve seats can be cut. Fist is to set the head in the machine and secure it properly. https://www.miataturbo.net/attachmen...ine=1337812162 The proper sized pilot is selected. https://www.miataturbo.net/attachmen...ine=1337812162 The head is now leveled in the machine. https://www.miataturbo.net/attachmen...ine=1337812162 Now to set up the seat cutter. First is to find where the seat is to make contact on the valve. https://www.miataturbo.net/attachmen...ine=1337812162 Now the cutter bit can be set. https://www.miataturbo.net/attachmen...ine=1337812162 The seats are cut. https://www.miataturbo.net/attachmen...ine=1337812162 Now the valves are lapped. https://www.miataturbo.net/attachmen...ine=1337812162 The small parts of he head have been cleaned, retainers, springs ect. https://www.miataturbo.net/attachmen...ine=1337812162 Valve springs are tested. https://www.miataturbo.net/attachmen...ine=1337812162 Most valve springs have been found weak, so New BC1100 springs will be installed (stock spring on left, BC spring on right) https://www.miataturbo.net/attachmen...ine=1337812162 A broken exhaust stud was found and removed. https://www.miataturbo.net/attachmen...ine=1337812162 The valves are ground. https://www.miataturbo.net/attachmen...ine=1337812162 Ground and ready to be installed. https://www.miataturbo.net/attachmen...ine=1337812162 Now the head can be surfaced. The head is set up and secured to the milling machine. https://www.miataturbo.net/attachmen...ine=1337812162 The proper surface finish is milled for the head gasket to be used. (a composite for this one) You can see that this head was belt surfaced before. https://www.miataturbo.net/attachmen...ine=1337812162 The head is now blown out to remove metal flake from milling and seat cutting. Now that the machining is done, it is time to assemble the head. Valve tip height is checked to make sure it is in spec. https://www.miataturbo.net/attachmen...ine=1337812162 The valves are removed, lubed up and slid back into the same hole they came from. https://www.miataturbo.net/attachmen...ine=1337812162 A package of valve seals found in a head gasket set. https://www.miataturbo.net/attachmen...ine=1337812162 Now the seals are pushed on by hand https://www.miataturbo.net/attachmen...ine=1337812162 Now seals can be installed, this is my “hi-Tech” seal installer. https://www.miataturbo.net/attachmen...ine=1337812162 Now the seals are tapped into place securely. https://www.miataturbo.net/attachmen...ine=1337812162 Now spring shims are installed if needed. https://www.miataturbo.net/attachmen...ine=1337812162 The spring shim goes on before the spring seat. https://www.miataturbo.net/attachmen...ine=1337812162 Now the cleaned spring seats are installed. https://www.miataturbo.net/attachmen...ine=1337812162 On top of the spring shims. https://www.miataturbo.net/attachmen...ine=1337812162 The new valve springs, BC1100 https://www.miataturbo.net/attachmen...ine=1337812162 Now the new BC1100 springs are placed in the head, on the spring seat. https://www.miataturbo.net/attachmen...ine=1337812162 I will set the head back in the TnS 2000 Seat and guide machine, Using this adapter I will compress the valve springs. https://www.miataturbo.net/attachmen...ine=1337812162 Now before I compress the spring, I will take the valve spring retainer. https://www.miataturbo.net/attachmen...ine=1337812162 Install the valve locks, https://www.miataturbo.net/attachmen...ine=1337812162 Then place it on top of the spring. https://www.miataturbo.net/attachmen...ine=1337812162 Now with the spring and retainer compressed, https://www.miataturbo.net/attachmen...ine=1337812162 I can push the valve locks into place. https://www.miataturbo.net/attachmen...ine=1337812162 Repeat the process till all the springs and locks are seated properly. https://www.miataturbo.net/attachmen...ine=1337812162 Now this customer is going to install new 3g HLA’s. So no need for me to install the last of the valve train. I check the valve to seat seal one last time. https://www.miataturbo.net/attachmen...ine=1337812162 I did install the cam tower caps on their proper side and position. Each cam tower bolt received a quick dip in oil, since all the bolt threads are dry. https://www.miataturbo.net/attachmen...ine=1337812162 Now the oil galley plugs received a dab of sealant. https://www.miataturbo.net/attachmen...ine=1337812162 Then started by hand to prevent cross threading. https://www.miataturbo.net/attachmen...ine=1337812162 Then tighten to seal. https://www.miataturbo.net/attachmen...ine=1337812162 I measure the head for thickness and make a not of how much was removed. https://www.miataturbo.net/attachmen...ine=1337812162 The final step is to CC the combustion chamber so proper compression ratio can be calculated. https://www.miataturbo.net/attachmen...ine=1337812162 This head is now done, and ready for the customer to pick up and install. |
Wow man, thanks for posting that. Now I can understand why machine work costs so much. I'm getting ready to drop my head and block off so its nice to see what may be done.
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This is really sweet info. Will need to re-read a few times. Thanks
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nice write up!
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Now that you have read how a basic head build is done...
this is a bit more advanced.. Head build_Modified https://www.miataturbo.net/engine-performance-56/head-build-modified-66086/ |
May I just slip this here and maybe have you just reading it and telling me what I should do....
https://www.miataturbo.net/showpost....28&postcount=1 I hate thread Hijacking, but I would like to have a real machinist taking a look at it.... Thank you |
holy crap! thats a lot of work. In the next few weeks, I'll be taking the head off an mx3 and sending it in for some cleaning and machining.
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I dont have enough 'props' I can give you
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