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Twin cam head for the L6 from Derek at Datsunworks


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  • 4 weeks later...

Guess what I'm making?




So the cast steel camshafts have turned out to be a lot more trouble than they were worth. At least for now. After I'm through whittling on these I may have a different opinion.


They start off as 2" OD 8620 tool steel. The lobe OD is 1.875" and the smaller sections go down to about 1" so that's a lot of cutting. Plus although my lathe is converted to CNC it's not exactly a production machine. But so far it's going better than I thought it would.





Part of what made this more attractive to me was I added flood coolant and a partial enclosure. That makes a big difference with this kind of work on this kind of lathe.





Tomorrow I'll back away the tail stock and drill and tap the snout for the timing gear bolt. Then I have to groove the bearing surfaces for the oil. When I get both blanks done the lobes will get profiled in the mill on the 4th axis.


The head is still down at Mazworks and based on what I've seen so far I'm pretty confident That the valve seats are all going to be in the right place. Hopefully it will be done in the next week or so.


One intake manifold is cast and I'm waiting on the other 2. The valve cover pattern is down at the foundry and I think they are pouring it next week.


Xnke has been making progress on the header so that's a good thing as well.


Lot's happening just happening slowly:)

Edited by Derek
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Wow, why have I been away from hybridZ? There simply aren't words. No really. Not words. The only thing I can muster is )!*#$)!)I!)#I$)UI_(!U$(PU!POU$PU!@DJOPJ!!(!!!!!OP@#!.



So yea. Not that I can afford it, but 10k would be a DEAL to have one of those made. Hell, having one shipped to someones door ready to bolt on for 15k would still put it in a price/HP range of any similar HP/Liter NA inline 6 builds. Can one REALLY get a 350hp BMW NA inline 6 into their S30 for less? Besides, this was swagger for not just days, but lifespans.


When I start making yearly what most people spend on their house I'll ring your phone... Until then, good gawd please keep up the work.

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Shit, I haven't been on the forums in a while. Looks like I've missed a lot. Those cams became quite the PITA job! But all looks great. Still outsourcing the lobe grinding and polishing?



Isky is going to do the heat treating and final grind.



Finished all the lathe work on one cam. Pretty happy for a first effort. 




The blank started out weighing 22 lbs. The cam as you see it is now 7lbs. That's a lot of whittling!






Now that the first one is done the second will go a lot quicker. Then I'll start on the lobes.  

Edited by Derek
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The process control after the cast was not so good. They normalized them in a non atmospherically  controlled furnace so they developed a lot of scale. When they ground off the part lines they ground into the cam profile more than one time. They were really warped.  I ordered a second set without part line cleanup and without normalizing but it was taking forever. I had to wait for them to have a full pour of 8625 before they would pour them.  I got tired of waiting so I decided to take a crack at machining them. As my luck would have it I got an email that the second set was cast. I was waiting until I got further along with the machining to cancel the castings so now I have 8 cams:)


There was a large portion of interested parties that were not going to use a cast cam no matter what. The pricing will be more than cast but I'm hoping a lot less than I was quoted. Also because they will be a known alloy it will open up the available pool of cam grinders willing to take them on. 


When I get the new castings in I will evaluate what direction I'm going. I'm going to use the machine cams in the prototype for sure. If using cast cores makes financial sense in the long run then I'll work with them. The next core I machine should give me a pretty good baseline for the lathe work.

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Well it's moving along!



Just picked it up from Mazworx. I came out really well considering what they had to work with.


I was really happy to find out when I dropped the head off to find out that Jim Thompson formerly of Sunbelt Engines is now doing head work at Mazworx. He did all the work on the head. I wasn't in a position to post about it then as I didn't get his permission to mention it. It really felt good knowing "an old hand" was going to be doing the work. 


I knew there was going to be a little bit of an issue with the exhaust seats as I had to move the valves from their original position. There is a step on one side that I can blend and a ledge on the other side. None of us feel it's going to be a problem for this build. The next design will have a smaller as cast seat area so there will be more meat.




The other issue is for some reason I felt it was a good idea to put a boss inside the port for the valve guides. They won't be in the next gen either. There is plenty of meat for the guides without the bosses. 




Top side shot. Nice view of my shitty attempt at tigging up a shrink cavity on #1. JB welt here I come:)





I've waited a long time to see this:



Yea I know they're not in the right holes:)


So now we're in wait mode again as Ron Iskidarian is on vacation until the 10th and who knows how long it will take to get the cams done. I have plenty to keep me busy finishing everything else up so the timing may be fine.


I can't tell you what a relief  it is having the guides and seats in. There was no good plan B if they were off.

Edited by Derek
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Nice!  The head that I had to trash was done by Jim Thompson (supposedly).  Unfortunately it appeared that the PO blew a head gasket and allowed water to sit in it for a few years.  When I took the motor apart, I found out both the head and block were toast.  So I bought another head from a member here and have been having a few problems that I believe are related to it.  So now I'm hoping this will solve all of my problems.  I'm pretty sure complication and money are usually the best way to solve engine issues.

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Derek, you, me and JeffP should hang our CV's out so budding young engineers can follow in our footsteps matriculating at our respective alma-maters...


Nice to see that valve sitting in there nice and snug.

The bosses around the valve guides just look like they need to be slightly less deep...I doubt they will materially affect flow in any way, but the support for the valve guides and heat transfer they provide will have benefits... You're going from the cam side of the head on machining the holes right? So it's not like you have to fight the bump to keep,the drill centered. I was never much of an exposed or completely cut off valve guide kinda guy. The flow possible here in current layout will far exceed what most will ever use!


Got a note from a bud in Okinawa. Seems the white OSG Car I took photos of in 1988 STILL EXISTS and unknown to me was a friend of HIS... He was 20' away from it yesterday. Why did this come up? Well, he has the head from the car and is starting his OSG Build... Mentioned watching the progress of this head buildup and may be interested as his build of the OSG will be "heritage", for others to see and appreciate...but since he has access to that original white S30, mentioned that "it would be great to get one of those heads so we can actually race the thing without worry that I'm breaking the only one on the island!" Apparently one of those original B1 heads was scrapped by the owner after the car "expired" so the number of Extant B-1 Examples declines even more.


To think of the possibilities of an originally-powered OSG S30 might one day be again be resurrected to its former glory by running around powered by an L-Powered Datsunworks Head-Topped mill makes me smile!

Edited by Tony D
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OSG = OS Giken.

No, you can't read about the car I am referring about. While I did have access to the Internet in 1988, it was on a green monochrome Wyse Monitor that was solely text-based. Not really a vehicle for posting photos at that time. Any images exist solely in the firm of Fujichrome 100 C41 Process negatives and photographic prints in my album back in the states.


This car was at Body Shop AY outside Kadena AFB Gate Four where my S30 had its body done in 1981 (when owned by Roger Puffer.)

I took several,photos while stopping through for this or that. First the car possessed a 3.3L SOHC and later the OSG headed mill. It was when the OSG engine was in it that I got a ride. At the time I had no idea it was something like one-of-twelve in existence.


My friend there bought the head some time ago...but I didn't realize it was from that car until our recent exchange. Kind of happy to hear the car is still around. One day I'll get back to shoot / scan the photos of the visits.

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Then likely you saw my car running around if you got anywhere near 400MMS area, Roger had the headlights glassed over, and pop up headlights in the hood, Porsche 930-Style Flares, dark blue car. It went away to Nellis and he brought it back on a subsequent assignment. I bought it after he had it stored for years out by my place in Morgan Mannor. He originally sold it in-squadron but the guy that bought it couldn't get it running using an EFI Pump into triple Mikunis with four year old typhoon water contaminated gas...his plan was to get it running for his transfer to the PI... I ended up buying it, then selling triples, exhaust, and engine off it for a net cost of $400 profit!


The guy that bought it was none to happy following from Kadena to Torii Auto Hobby about a half hour behind me just about in time to see me fiddle 5-6 minutes and have it running perfectly. Engine went to a guy we called BunnyMan in Chute Shop I think.... He had the head and cam redone at RS Okinawa, as the slugs were hand built by Clyde Tomoyose at his place in Naha. 2mm pop over deck. With the head reworked and the RS Okinawa cam, BunnyMan's 2/2 Fairlady was wicked...


Never actually met Roger, talked to him a lot on the phone trying to get the car registered in the USA, and then again dealing with CA Smog & BAR Referee...


Clyde was the guy who told me where the bodywork was done. And Roger confirmed it...hence my hanging around for bits and bobs. And it's how I ran across the OSG Car.


I digress...

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