Lotus TC cylinder head repair

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Following in Castweld's footsteps . . . Lotus twincams head from the mid '60's was damaged when the head of the intake valve broke off at ??? RPM.  Preheat at 350 F, weld hole and other damage with A356, age at 350 F, straighten (so the cams bores were straight), reshape chamber and ports with carbide burr and sanding cones, make and install new guide and seats, machine for spark plug, surface and deburr. Dynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A
Reply:Nice!  How 'bout a pic of the car?
Reply:WOW Looks good great job.
Reply:dang, that is killer work right there.  Wish I could do stuff like that. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:HOW do you DO that?Incredible!I could probably weld it up. And that would be the end of my skill set.How do you set it up to cut new valve seats? How do you set up the spark plug hole in exactly the right spot and angle?Seriously, machine work is like FM to me. I have a buddy with a full machine shop and I go watch him run the lathe, mill and stuff as much as I can. Every day it's a new and different project. Please show how you do that stuff. The welding is cool too. But I know how to do that. heheheLincoln Power Mig 210MP MIGLincoln Power Mig 350MP - MIG and Push-PullLincoln TIG 300-300Lincoln Hobby-Weld 110v  Thanks JLAMESCK TIG TORCH, gas diffuser, pyrex cupThermal Dynamics Cutmaster 101My brain
Reply:Originally Posted by dallas_Nice!  How 'bout a pic of the car?
Reply:Originally Posted by Joker11HOW do you DO that?
Reply:That is very impressive work!  I tip my hat.
Reply:Wow!!Awesome repair! I agree with Joker. The skill-set needed for a job like that is not to be underestimated.http://all-a-cart.comWelding Cart Kits and accessories
Reply:Why was this cylinder head repaired and not replaced?Parts availability issue?Do you mind offering a ballpark price and timeframe on this type of work?  I think it might offer some perspective on what type of skill and machinery is involved.I've typically only seen this type of repair on $5000+ each Brodix heads, etc. due to obvious reasons.
Reply:Originally Posted by 95PGTTechWhy was this cylinder head repaired and not replaced?Parts availability issue?Do you mind offering a ballpark price and timeframe on this type of work?  I think it might offer some perspective on what type of skill and machinery is involved.I've typically only seen this type of repair on $5000+ each Brodix heads, etc. due to obvious reasons.
Reply:You forgot to scribe your signature in it...great job.
Reply:Yo bud great save and awsome work! Pat youself on the back for that one I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:Nice.17 hrs labor, eh?  Maybe I'm not so slow on making/repairing things after all.      The best laid schemes ... Gang oft agley ...
Reply:Wow.Tremendous job. That is an amazing piece of work!PlasmaCam CNC cutterLathe and Band SawClamps
Reply:Thats as good as it gets. I see you found a source for the A356. A few minutes welding and several hours standing in front of Bridgeport then die grinder.. Fun ain't it?Again, nice repair.PeterEquipment:2  old paws2  eyes (that don't look so good)1  bad back
Reply:Very nice workLarryMiller XMT 304 CC/CVSyncrowave 180 SDLincoln PowerMig 255XTTermalDynamics 52Lincoln 305GComlpete machine shop to back it up
Reply:Solid work. Thanks for sharing. I'm so glad there are people like you who exist in today's day and age so that people can continue to appreciate old classic cars.Miller Diversion 165
Reply:Originally Posted by 4sfed  Preheat, weld, age, straighten, reshape chamber and ports with carbide burr and sanding cones, make and install new guide and seats, machine for spark plug, surface and deburr.
Reply:man that's sweet nice jobMILLERMATIC 212 AUTOSETMILLER BOBCAT 250MILLER DIALARC HFMILLER 15A SPOOLGUNMILLER S32P WIRE FEEDERTHERMAL ARC 186 AC/DCPAKMASTER 100XL PLUS
Reply:Nice repair.
Reply:Very Nice job!! Super repairMiller 250DX HTP 221 DV AC/DCHenrob O-A Miller 180 MigMiller 150 Inverter   Hobart 10,000 Welder-Generator   Have a good day!!!
Reply:Nice job..Did you CC it after?...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by freedomgliI'm so glad there are people like you who exist in today's day and age so that people can continue to appreciate old classic cars.
Reply:Originally Posted by zapsterNice job..Did you CC it after?...zap!Excellent job, and thanks for sharing.-AaronJet 17.5" Drill Press1942 South Bend 16x84 Lathe1980s Miller 320A / BP --- 2013 Power Mig 2562012 Jet 7x12 Horizontal BandsawVictor O/A Setup
Reply:very nice repair well doneMiller Xmt 350Lincoln Ln-25Ahp 200xSmith Gas Mixer AR/HTig is my Kung FuThrowing down dimes and weaving aboutInstagram http://instagram.com/[email protected]
Reply:So, just out of curiosity, could one use a laser measuring device of some sort on an adjacent combustion chamber from the same head, transfer that data into a CNC machine and actually have the CNC reshape the chamber exactly like the reference copy? Seems like that would be the hot ticket. Of course, it leaves out the craftsmanship of your work, but it might make jobs more affordable? 17 hrs of labor can't be cheap, I assume.Lincoln Power Mig 210MP MIGLincoln Power Mig 350MP - MIG and Push-PullLincoln TIG 300-300Lincoln Hobby-Weld 110v  Thanks JLAMESCK TIG TORCH, gas diffuser, pyrex cupThermal Dynamics Cutmaster 101My brain
Reply:Joker, you could do that, but it would only really be cost-effective with higher volume applications. For one-offs it would likely take more time and money for the first one to get done as the tool paths would have to be tested and validated. You don't want to set your CNC machine loose on a rare piece if unobtanium without doing your homework first.Miller Diversion 165
Reply:Originally Posted by MoonRise17 hrs labor, eh? Maybe I'm not so slow on making/repairing things after all.
Reply:Incredible work. I'm with you on the antique Alfa powertrains. Absolute works of art.How much shim are you talking to straighten that?Brian LeonardAppalachian Ironworks L.L.C.434 Long Branch Rd, Marshall, NC 28753828 649 9966828 702 [email protected]
Reply:Nice save, as with anything welded, proper fit up and prep takes much longer than the welding.Leo
Reply:Originally Posted by 4sfedSo you want all the secrets?Before anything else is disassembly . . . cams, springs and valves, then an hour between the cleaning tank and bead blaster . . . and some time with a carbide cutter prepping.    Valve guides are not driven out, the portion that is pressed in the head is machined out to a thin wall while leaving the end extending into the port with it's original I.D.  That virtually eliminates the press fit and the chance of damaging the head.  The smaller I.D. is used to push the guide out of the head.  Unfortunately, this guide was broken on the end and required a little more effort to remove.  As Castweld said . . . a few minutes of welding and several hours standing in front of Bridgeport then die grinder.  Machining started with the internet search to determine the valve angles. Then there's setup . . . finding the center of the bore for the valve seat that only partially exist because of the welding.  The machining is done in small increments until a clean surface is obtained.  Larger seats and valves had been installed so there's precious little extra room for even larger seats.  Custom valve seats then made . . . definitely nothing available off the shelf.  Then adapters for the seat driver to fit the custom seats.  Almost forgot the valve guide.  The valve stems are smaller than stock . . . it's a racing head with custom guides.  Heat to 350 F and install.Now cool and test fit the cams . . . oops, the cams won't turn.  The head is warped from the welding.  The center journal is a couple thousands high.  The head is bolted to the toque plate with shims under the ends of the head (inducing a reverse bend) and "stress relieved" for an hour.  Cool and reassemble.  Better, but not enough.  Reassemble on the torque plate with thicker shims and back in the oven.  Third time's the charm and the cams turn freely.  Now all that's left is to reshape the chamber, ports, rough in the seats and surface the deck . . . and cleanup . . . part of the job.  Quick and easy repair!  That would be wonderful, but it would add another setup, and I'd have to double my rates to pay for the equipment.
Reply:While you are waiting for the valves, I woud also pressure test the head to make sure  there are no hidden cracks somewhere. I don't recall you saying you did previous.I am an automotive machinist and  just worked on the same type of head a few months ago. Not as much fun as your job though.  My head got new valve seats,valves,springs, & guides.Good job on your part.Ron
Reply:Originally Posted by app-ironworksllcHow much shim are you talking to straighten that?
Reply:Nice work!I have been doing some work over at a local shop on a thunderbird. Happens to be a guy that brought in some stupid rare jaguar there, says the motors original head is cracked and he has taken it to 4 different shops already and they all say they can't fix it. Apparently he is pretty impressed with the work he has seen me done on the bird so he asked if I could fix the head and a few other parts for the car. I have yet to see the head, I told him if its made of metal I can fix it.
Reply:4sfed said: "I agree, but I'm a little short on fixtures for this particular head and there are 20 studs for the cam caps that would need to be removed.  I have a plate drilled for the Alfa heads, but not the Lotus."Are you saying you bolt the head so the cam journals are against the torque plate? We do it so the deck is against the plate with the shims on the end of the head. Curious,Ron
Reply:Originally Posted by 4sfed.005-,006 on the interference, the angles were pre-cut in the lathe and touched up with a Sioux driver and set of stones.
Reply:Alex, right about the welding. Had my head fixated on the straightening aspect of the job, not the welding ( probably shouldn't admit that part huh?)Ron