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Everything posted by Derek
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Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Thanks. Originally I was going to cast it as part of the front cover. The general consensus was exiting the water over each exhaust port like the OSG head was a superior way to go. The production models will be that way. I'm going to machine a separate elbow for mine and incorporate it into the timing cover. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Been working on a bunch of stuff so I guess it's a good time for an update. Got the pattern done for the cam cores and it's sitting at the foundry waiting to be poured. Got the pattern done for the front timing cover and got the casting back from the foundry. Today I was able to finish up the machine work on the timing cover and head. The timing cover is a bit of a kludge as I had printed the mold before I fully finalized the timing cover. It works but it will be better in future versions. I had to get it cast and on the head so the machine shop could surface it all together. Here I've mounted the cover to the front of the head, machined the surface flush with the bottom and drilled the front holes for the lower cover. The front lip is a little thin. I'll add material to the pattern to thicken it up. I really should have left more material around the entire head. That way I could have made a cleanup pass around the whole thing. I have enough material on the valve cover to create a lip to hide it so it will look good when it's buttoned up. This head will have a water outlet on the side of the timing cover but future heads will use a coolant manifold like the OSG head. Very happy with the internal fit. I need to rig something for the front cover bolts. The holes are right on the step. I'll add bosses to the pattern so it won't be a problem later on. So I didn't try to make it fit this well but the "as cast" fit between the factory cover and my cover couldn't have been better. Of course it's in a spot where no one will see it Got the exhaust flange from the laser cutter. I machined an adapter block to go from a stock Nissan head to my flange. When bolted to the Nissan head it will position the flange exactlyish where it will be with the new head. This will allow the header to be fabricated on a car without being dependent on having the head. Next up is the intake manifolds and valve cover. I'm doing three separate identical manifolds. It's a little more expensive to cast but a whole lot safer as you're dealing with smaller items. Machining is easier as well. Will it ever end Derek -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
For sure. I remember adding that material to the intake side toward the end of the design proscess. My plan is to redesign it like the exhaust side. It looks a lot better. -
Proof that most car problems can be solved in a moment of "reflection"
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Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Please do! -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
That's one of the reasons I went with the KA setup. When I pulled the K20 chain out of the box I was like "is this a joke". It's soo small. Time will tell If the single roller will work or not. There is no way I'm going to make a set of gears until I see this one stretch -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
I need to mention that the Honda chain is a standard style chain and not a roller. Also it is closer to a .250 pitch not .125" Too many details rolling around in my head to keep it all straight:) -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Single up top or on the bottom. Non of the KA sets that I saw have a double on the lower chain. I did see some that had a double up top and that set will work on my head as well. My theory is the roller rockers should reduce the forces enough so that a single row will work. The K20 only has a .125" pitch single row chain. It is also one single chain. The KA chain is .375" pitch. Because of these differences my gut feeling is it will be fine. When I build the head I'm going to buy a set of (probably) Brian Crower BC1040 springs. Even though my build would run on stock springs I'm hoping to replicate some of the stresses a higher HP build would have. This should give the valve train a pretty decent test. I realize there are more dynamics than just spring rate at play but it's the best I can do. Derek -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Made a little progress Saturday. Machined the front of the head. I knew this was going to be a PIA from the word go. I just don't have a proper angle milling head to really go at it. I bought a used angle head on ebay a few years ago. It's designed for woodworking but it was cheap so I went for it. In the first shot I'm using the probe to indicate off of the cam bores. Here I'm surfacing the front of the head. The finish came out a lot better that I expected considering the rigging I had to do to make it work. Faced the upper timing chain tensioner and the upper chain idler mount, spot drilled the timing cover and tensioner holes. I'm going to drill and tap those manually as I didn't have anyway to hold drills in that angle head. No biggie. Got lucky on the pilot bore on the idler mount. You have to tap it on with a plastic hammer. The chain fits well. I knew I was going to make a spacer set for the bottom gear since it's a single not a double like the stock chain. The single chain tracks along the center of the guides now which is what I was looking for. Got the pattern finished for the front timing chain cover. That's heading to the foundry today. Hopefully they will cast it this week. Still have a lot to do but I feel like I have a little momentum. Derek -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Got the head back from X-ray on Saturday. No big surprises. Here is a shot of the front half Here is a closeup of a known shrink porosity problem. I knew it was there because you can see it from the top. I wanted to leave it to see what it looked like in the X-ray. You can see it leads all the way over to the valve guide bore and in fact you can see it in the bore. I'll do a weld repair on the top and call it a day as it's too small a defect to affect the valve guide. Controlling solidification shrinkage is one of the tougher aspects of casting metal. We'll try something a little different on the next one. Every head will be x-rayed before they get sold. This way people can have confidence in the casting before they invest in machining. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
I'll be supplying a cast steel core for an additional price. It will be up to the end user to make arrangements from there. I will also be providing the necessary data to have machined steel billet cams produced. But ultimately It's going to be up to the builder of the head to determine what they want. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Thanks Leon. I think it's important for people to realize just how much effort goes int producing things like this. In theory there is nothing going on with my head casting that would stop someone implementing iVTEC. But it would take a bit of engineering. I hope someone buys a casting and makes it happen as that would really be the best of both worlds. The way I beat...er...drive my car it would probably just be engaged all the time anyway:) -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Cam scan Well everyone in the brain trust agreed that the numbers on the K20A2 cams would be a good starting point for my motor. I bought a used set of cams off of ebay. I used my structured light scanner to capture the lobe data. The scanner projects a light pattern against the object and photographs that pattern The software creates a mesh from the pictures. Here is a shot of a single pattern to give you an idea. I painted the cam white for a better scan. This is the resulting mesh. The mesh has holes as I only capture as much data as I need. I run a plane through the lobe so I can derive curves. And use those curves to develop a solid model. I can then use the deviation calculator to see where I'm at but I can usually tell if I'm off or not as I'm drawing it. On a larger project it's nice just to make sure I didn't miss a feature. Now I can start designing the cam core blanks and patterns. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Time to leave the nest! Heading to JAX for X-ray -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Actually if there was a market I would make one but I think there are simpler cheaper options for 4 bangers. I could be wrong though as I've never researched it. It seems like the KA swap is pretty straight forward and affordable. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
How about now So nice of you. It'll go out today Probably not -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Well it's out of the mill! OOPS Not enough clearance for the tool holder. Well that's it for a week or two. Got a bunch of pattern work that backed up so I have to get a handle on that. Also realized I need the front timing cover done before I have the head surfaced. I may machine that out of billet 6061 as I'm not too sure if the production heads will have the water outlet coming out of the front. I guess I could have cleaned that block up a bit -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
This man has balls of steel. I machine a lot of castings and I wouldn't touch that And now that "that cat is out of the bag" will the new owner allow you to post pics of the process? I would LOVE to see that happen. I'll PM you about the cams. Derek -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Please do. Preferably in the mill you're using for the work. Must be a huge! -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Where were you about 160 posts ago Basically although I could do it with the equipment I have it would be a stretch. Out of all the cam companies out there very few make their own cores and those that do had an attitude like "go away kid you bother me". The pricing I got pushed the overall price of the head out past where people could justify it. I'm having them cast out of 8625 so from a chemical (or metallurgical ???) sense it's close. I know it's not as strong as cold rolled but it will probably do for the lower HP units like mine. Ron Iskenderian will be taking the cast cores all the way from the rough state to final grind including hardening and straightening. NOW if you are interested in producing cores then I'm more than happy to talk to you about it. So much so that I'm going to PM you on it. Derek -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Surface the top and bottom. Install the valve guides. Cut the pockets for the valve seats and install them. multi angle valve job. Line bore the cam towers if necessary. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Here's your daily fix Got all the intake valve work done. Got a little carried away with the machine allowance on the intake side! Had to take it down almost .375". I had to leave that wall around it because the mill was hitting the side of the head. You can see where it nicked the intake bolt boss. Every port looks just like this. Man I like digital mold making. The accuracy is just amazing. I should have the rest of the machine work on the four sides done tomorrow. Then it goes to get radiology testing. I would normally do that before machining but I was going to machine it regardless of the outcome. I don't foresee any problems and it's mainly an insurance policy at this point. After that I will send it to get impregnation and then it's off to Mazworx for the headwork. Cam design, cam core pattern and cast cam cores are next on the list. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
yea you won't be lacking in surface area! -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Well today was a big and stressful day. I got all of the exhaust valve work done. Drilled and reamed the valve guide holes and machined the valve spring bosses. Everything seems to be working out as I planned. This is the best part. The bores came through right where I needed them to. After I had printed the sand molds I realized my valve angle was off by half a degree. That's why the bore of the valve guide is not centered on the boss. Future heads won't even have that boss on there. I'm not really sure why I put it in as there is plenty of support for the guide without it. So far so good. Tomorrow is the intake valves and Wednesday should finish off the intake side of the head. -
Twin cam head for the L6 from Derek at Datsunworks
Derek replied to Derek's topic in Nissan L6 Forum
Thanks. I feel like people need to realize just how much work it is to bring projects like this to fruition. Of course if it wasn't for the sand printing none of this would be happening. I also look at it like I have a bunch of eye's on it that may spot potential problems.