Derek

Well I'm hosting all of my twin cam head picks on photobucket and for now the links still work. I can't even imagine having to go back and replace all of that:( Probably just a matter of time before they get around to hitting me.

Making progress on V3. The major machining is all done. I have a few little handwork items left but other than that it's pretty close to being finished. I had to build the front timing cover up a bit with some weld. I’ll blend it in better by hand. I’m also going to counter bore the bottom screws on the front timing cover so they will be hidden. That is a lot of valve cover:) The cams are over at Crane getting heat treated and the bearing journals ground. They said I should have them back by the end of the month.

Thanks for the tip on the 4943 rod. Although I hope to not have to repair this head that's good to know. Just for fun I sent a part of a Honda K20 head down to the foundry. They are going to test the rockwell on the exterior vs the combustion chamber. I was curious how the combustion process over time would change the hardness. I really don't have any data as to what sizing they did. Based on everything I see I'm really pretty sure it was operator error. This is all pretty basic stuff so if the seat bore isn't cracked then either the seat itself fractured or it was installed improperly. Well the seat bore isn't cracked so.....

Chrome moly I didn't specify a fit. I left that up to them.

Actually it was a generic aftermarket valve. I think I would regret not hanging on to my first cylinder head so It will be cleaned up an live it's life out in the comfort of a dusty corner of my office:)

If the seat doesn't drop in then you are removing metal. It may be at the sub atomic ( I pulled that out of my butt) level but it's removing metal non the less. So a press fit on an aluminum production head with massive process control is safe and predictable. On a custom or welded head getting the head heat soaked ( not just hot) and chilling the seats with nitrogen or equivalent seems like is the only way to ensure a proper fit. Otherwise you are broaching the hole. After more digging and analysis I'm leaning towards incorrect installation. But without a ton of checking and analysis it's really hard to say for sure. The car never runs hot even with the air on in traffic and this was in the evening. I have Speedhut gauges with warning lights so I'm sure I've never overheated it. The valve seat bore is not cracked. So eliminating those two things really points to defective seat/improper installation. The new heads with the HIP process will most assuredly improve the predictability and resilience of the metal. V3 machines like it's 6061.

Surprisingly there are more than I would have imagined. Rebello has 2 more sold besides the one I'm doing for him now and I have 3 people who either enjoy wasting theirs and my time or are ready to pull the trigger on one. The valve is bent a bit but still in one piece. So the problem was most def the seat. If this was a V3 head I would repair it without a thought but since it ultimately was heading for the shelf anyway I'm not going to put anymore resources in it.

Yep that's the way it went down. I figured the seat either cracked after it cooled or simply dropped out of the bore because it was oversized. I did a cursory inspection before I left the shop and didn't see any cracks in the casting.

Could be. Going to be tough to get an accurate measurement now that the bent valve has had it's way with the bore. The head was never overheated so I don't think it was anything on my end. I was going to change it out at some point with a production head anyway but realistically with the current demand I have for heads it will be 6 months or more before I'll be able to make it happen. Paying customers come first:)

Yea they did but I'm very hesitant to put any blame their way as they most definitely know what they are doing. But I will say I can't come up with any scenario where it was a problem with the casting.

I'm no expert but isn't there supposed to be something in there? Drove the car Saturday nite to pick up a pizza. Ran great. beat it as usual. Parked it overnight. Got up the next morning and fired it up ran a little rough then it ran a lot rough. Towed it to the shop, pulled the plugs and number 6 shot a geyser of coolant. The seat beat the chamber until the head deformed and cracked. Alas poor prototype head....You served me well. Sniff.

Wow that is really pretty. You sounded sad in the video that you had to turn it off:) Great stuff. Derek

Got the head back from the foundry and for the first time I have all the parts under one roof. Figured I'd take a family photo:) Guess I better get busy on the milling machine! Aww you're making me blush.

That's what they explained to me when I was talking to one of their engineers. My main concern has always been micro porosity in the chambers and deck. My hope is that having the castings HIPed will help me sleep at night. Oh and make for a better casting:) Oh you fancy pants facilities with your fancy pants destructive testing and analysis. The foundry is still a production sand cast foundry and I'm doing one casting at a time right now and can't imagine doing anymore than four at a time so that limits my options. I'm really confident in my metal flow and risering at this point. The casting has mimicked my flow/thermal analysis exactly so I'm very confident that I'm not getting any huge internal inclusions.

Been a while since I updated so I guess it's time for a big dump. Are we still doing phrasing? So a whole lot has been going on behind the scenes as far as the processing of the raw castings and some big design changes. First the processing. I'm always reading about casting and cylinder heads. I was researching different methods of controlling casting shrinkage and porosity and stumbled across an article on how Edlebrock casts their racing heads. Not their production heads. They mentioned that they offer an optional service called "Hot Isostatic Pressing" Or HIP. The HIP process consists of heating the casting to a set temperature in a pressure vessel and then pressurizing it to as much as 30,000 PSI. This basically compresses all of the porosity out of the metal. One comment from the article that stood out was it makes the casting almost as dense as billet. It's so much denser that they had to adjust all of their machining speeds and feeds lower to accommodate the extra hardness. I'm now setup with a HIP provider and just had the last casting done. Because it's a heat process the head needs to be heat treated afterwards. It's currently at the foundry in the furnace as I type. I'm pretty excited about this since porosity is in every casting to some degree. You control it the best you can but there is always some. Going forward I'll most likely forget about X-raying the castings since if there is a large amount of porosity it will show up as a depression or a complete blow. I'm also hoping to do away with resin impregnation since there should be no leaks. I'll know better on that after I finish machining and do the pressure test. And now for the design changes. I have worked out how to implement Variable Cam Timing. This was no easy thing for sure but I'm all but certain it will work mechanically. The basic idea is I'm sticking with the KA24 lower chain and Idler. But I'm modifying the idler to accept a Honda K20 steel exhaust cam gear. This will allow me to run a shortened Honda chain and gears from a K20. Here is a picture of how that looks. The head has been made wider at the front, the valve cover is 1/2" higher to accommodate the gears and the timing cover has been redone. It's wider plus it has a solid section at the bottom front that will become the manifold for the VCT valve. In the above picture you can see the oil inlet valve to the left and then the advance and retard circuits on the head. The Honda exhaust gear gets the center machined out and 6 5mm holes are drilled through. The KA24 idler gear will have the outer gear machined off to match the bore on the Honda gear and 6 5mm holes drilled and tapped to hold the two together. Here is the timing cover and VCT in place. The VCT is from a V6 Nissan and should work fine as it has the same port sizes as the Honda. I've made the #1 tower wider to accept the grooving for the oil circuit. Since VCT and sequential injection require trigger wheels I redesigned the cams and rear tower. This is now the thrust area. It uses the stock Honda washers and bolts. The washers will work for Non VTC but will need to be customized for VCT and or sequential. And here it is in all it's glory. I raised the valve cover up a half inch and then brought the plug valley back down a half inch since it has to be at a certain level. It actually looks better since the relationship between the cam cover and valley is more pronounced. I added bosses under the valley to accept screws for the the Honda COPs. There are two. One fro the wire pointing forward and one pointing rearward depending how you want it to look. Now for the nitty gritty. All of the castings and cam towers are currently sporting these modifications including the one I'm doing now. So I guess that officially makes it V3. The non VTC cam shafts have been redesigned to work with the new towers but still use the KA24 upper timing set. If you want to convert from non VTC to VTC you will need new cams and all the other VTC specific bits. I have no plans at this time to actually make a running version of this myself. My main goal was to make sure that the parts I'm selling now will work with VTC if someone is brave enough to do it. My best guess is you are going to add 3-4 K by the time you have all of the bits working. There is a lot more to it than what you see here. ECU, sensors, plumbing etc. Not to mention I have no idea if the L6 pump will deliver enough volume to even make it work. But it will fit on the head:)

And Baby makes three:) Just picked this up from the foundry. Poured it a week ago and it had to go through heat treating. Everything came out great. Next stop is X-Ray inspection and then I can begin machining. A few more under my belt and I'll start to breathe easier.

Thanks for the info. I guess I'll mount it up and hope for the best. I'm not sure "hope for the best" is a term that should be uttered in a brake forum:) Derek

Did you discover the leak by bench bleeding? I just got my Wilwood master yesterday and now I'm having second thoughts. Thanks Derek

Here is how I decided to switch to S7. It was first suggested by the engineers at Crane. Not so much because I needed the strength but because of the ease of manufacturing. Cranes selection of K20 lobes blows. But they are right across the state from me and they have done great work on the cams so far. In order to get the pricing down on the cams I need to do some sort of limited production on them. Setting up to do 2 at a time isn't going to cut it. The steps with 8620 are at a minimum: Copper plate. This is outsourced since Crane no longer does it in house. Pre grind all of the areas that get hardened. This removes the copper. Since the lobes get ground they need some sort of profile to be chosen. That profile should be fairly close to the finish grind. This is the biggest issue that caused me to switch. Send out for heat treat. Again this is outsourced to a separate place. Cam bearing journals and front snout are then finish ground by Crane. Now here is the path on S7: Crane sends out for heat treat. Cam bearing journals and front snout are then finish ground. Lobes are already shaped by me before they go to Crane and are through hardened and ready for finish grind by whomever does it. Before I committed to the S7 I did some research and consulted with Schneider cams and Whitley Tune. The answer I got was basically the same. Probably overkill for this application but will work fine. I also saw this article from PRI magazine dated January 2015 http://www.bluetoad.com/article/Profiling_The_Newest_Racing_Camshafts/1892565/240066/article.html What got my attention was this: Totally Tool Steel The industry is already moving in that direction. “We have found S7 tool steel to be a good fit for some applications,” said Partridge, “not so much because it is stronger than 8620, but because the substructure of the material will support more load. Top Fuel and Nitro Funny Car cams, for example, need that additional substructure especially because of the load on the exhaust lobe.” And McInnis added how “a high-strength, tool-steel core allows a larger gun drill through the camshaft, which reduces rotating mass and, with it, parasitic losses in power output.” Tool-steel camshafts are not only more resistant to wear, but “stiffer, both in beam and torsional strength,” Knight added. “And they are not brittle, they are just very, very tough. One Alcohol Funny Car team bounced three connecting rods off of one, and we just straightened it out a few thousandths, touched up the lobes, and sent it out to run again.” All of that made me feel that S7 was a better choice for this application than a case hardened steel. Now if someone really wants 8620 I'm happy to make it but it's going to be a custom run and be pricy. And there is the tale of the S7 cams:) Derek

Quick update. Not much exciting happening. Waiting on the foundry to give me a tee time to pour the next head. V2 is moving along but the new owner is really tied up on other projects so there is no hurry. Here is a shot of my latest chain guide tensioner arrangement. Two custom guides and a stock L6 tensioner. So far this is the quietist of all the setups so far. I still have a tiny rattle between 2500 and 2800. I'm probably going to live with that for now. The Crane lobes are symmetrically ground and I have been told by multiple sources this can cause some issues with noise. This showed up today. S7 tool steel gun drilled blanks for the cams. I've decided to switch to S7 for a variety of reasons. Mostly because it is a through hardened core as opposed to case. This way I don't have to match the rough profile to the finished profile like I would with a case hardened cam. The machining time is the same so it just made sense. I'll still have Crane do the hardening and grind the journals. Time to get whittling Derek

Well if you have to ask...... I've posted this before but with 56 pages it's easy to miss. I don't have firm pricing on it yet because I haven't machined one in a production environment. I'm telling people to have 12-14K in the bank and depending on the build they want to do it should cover it. There are so many variables that it will be hard to pin it down for a while. The raw castings for the head, valve cover and upper timing cover are still $4500.00. What is really up in the air is how much the machining to get it from raw casting to ready for valve work is going to cost. I first threw a number of $500.00 and that was way off. Then I upped it to $1000.00 and that is probably low as well. I'm basing my estimates on having all the G-code proofed out and until I have machined one without a lot of tweaking I won't know for sure.

Because there is no kill like over kill in my book:) It started out because I was concerned with the tension and slack sides of the chains being so close together. My first thought was to add a divider there like you see on the top of a KA24 upper chain. I was afraid any chain whip during an overrun condition would rip it off. Then It morphed into it would be easier to do an entire channel. The orange brown colored OEM guides are made from nylon 4.6 which might as well be called unobtainum as far as I'm concerned. I couldn't find a source anywhere that wasn't "contact for a quote". That usually means you can't afford it:) The nylon 66 was recommended as a good second choice on an automotive engineering forum. Even still a .75" 1 foot square was like $80.00. The steel plate is drilled to hold a Nissan 13085-7Y000 guide so that can be used in it's place. It doesn't offer the same amount of guiding since it isn't custom but it will fit. This is off of a BMW I suppose it could very well snap the guide but the lead through the guide is only constrained in the top 3 inches. After that is's a natural flow straight down to the crank gear. With the valve cover off you can see the whole guide so I'll be able to monitor it for abnormal wear. The timing chain has been the bane of my existence. Since it's a linked chain it has to be a certain length. The difference in length by dropping a whole link is substantial. There are gear ratios involved and tooth count/crank snout diameter imitations as well as limitations because the K20 cams are so close together. I will say though even though the last setup was noisy at idle it never caused any issues performance wise so the system is pretty forgiving. Unless of course you break a chunk of guide off.

So this is what my car looks like right now. Actually it's part of a scheduled tear down and inspection. I have around 4200 miles on it. There is some burnishing where the roller meets the lobe. The cam bearing journals are burnished like the used cam towers but no galling. The main reason for the teardown was to rework the lower timing chain. Ever since I converted it from my first version that used the L6 guides to the second version that used the KA24 guides I've had an irritating chain noise at idle. At this point I'm pretty sure it was too much slack in the tensioning system. I had already decided to try and implement a curved tension rail to help reduce harmonics. After a bit of screwing around I threw in the towel and designed my own. Here is a shot of the finished piece on V2. It’s made from nylon 66. I found some references to people making custom guides with it on the internet. I made a steel plate that bolts to the existing rail holes. I inset the plate into the back of the guide for extra strength. I also pressed in bushings to keep it from crushing and loosening up. And here’s how many iterations it took to get it the way I wanted. And that's how the sausage gets made:)

This has been brought up before. I think when you can get the parts off the shelf as easily as you can get other things then it's viable. Until then it's a non starter.

I use http://www.timesert.com I like them better than helicoils for high load items. Ebay is usually loaded with kits.