In reply to Mr_Asa :
If someone were to build the necessary forge/furnace/vacuum setup to do low-pressure lost PLA casting of their own I4 or V8 cylinder head design, print the PLA patterns in pieces at home and assemble/anneal them together, plaster cast and then machine a bespoke head - it would not seem like a more complicated or ambitious project than what we see in this thread. Arguably less.
mke said:In reply to Syscrush :
funny to listen to him....the first time I drove the 308 (I bought it site unseen so it was dropped in my driveway) I literally called my father from the car and said "you HAVE to get one of these! This is amazing!" I'd never driven anything like it...kind of a fluidness about the way it moved. I agreed the car doesn't do anything as well as a modern car but its kind of a sensory overload when its in motion.
I have similar feelings about my CBX - but it's 100% about the motor. When I first put it on the road, the brakes were OK, handling was OK, suspension was horrible and dangerous - but I was addicted. I figured that with time and care, this thing could all be sorted out. That road has turned out to be a lot longer than I anticipated, but I'm still committed.
Did something! Put some cuts in the 3 intake seats I want to replace to make then easier to remove next time I'm in the shop
Woke up early and rather than lay there staring at the ceiling I got up and pulled the seats out. I tried it a little different this time and it seemed to work fine. Yesterday I cut 3 grooves most of the way through the seat but didn't take any risk of cutting the heads. today I welded across the groove thinking that would be enough to shrink the seat.....it worked fine but not sure it was any faster or worked and better then welding alone....less heat next to my new exhaust seats was what I was thinking about, no idea if that was true or matters but they are out now.
Put the seats in the freezer and fired the first burner on the grill...
L: Hey!..Get away from my grill! We're having burgers tonight. Shoo.
me: But today is Fryday, I thought we'd be frying stuff? and its my grill anyway
L: they were out of french fries and if its not in the shop its not your...shoo
Me: after dinner then
L: 
me:(to myself) pretty sure thats a yes....heads on to heat around 6, seats in them by 7 I guess
Cooking
Seats in
I recut the 3 new seats so that task is done.
One head still needs me to deck it .010" to match the repaired head. Then cut the exhaust seats but I cleverly didn't give myself any real reference to shat depth to cut them to exactly. What I probably need to do is rough cut 1 then check its lash to see how much deeper to go, a little slow but it should make it come out right. Of course I also cleverly send away the valves so.....I will deck the head then set the mill up for the exhausts and bore all the seats to size, then I can move on the blending the seats into the ports which will all take quite a bit of time. After that I still have a little cutting to do on the new liners before they can be installed in the block so it can go for finish hone. After that I still have lots of stuff to clean up so its not like I would actually be holding on the valve for some time even if I was allowed full time in the shop...which I'm not 
Setup and decked the 2nd head tonight with no problem
But having just cut the intake seats they were still on my mind which made me notice that the edge of actual sealing angle of the seat is literally right at the deck, I looked at everyone on both heads and they are all still fine but any more off the deck means recutting the seats deeper...I'd forgotten or perhaps never realized how close I set that up originally. To be fair to me these are 34mm intake valves stuffed into a head designed for 29mm valves so things were bound to be a bit tight....I have no idea what ferrari was thinking taking a perfect exhaust valve size and calling it an intake ???? 
Here's something I'm pondering. The spark plug hole in cylinder 8 (the damaged one) isn't very good. The plug had gotten smash and stupid me screwed it out taking out most of the threads. I welded as deep as I could when I was repairing the chamber and it would PROBABLY hold....but this is supposed to be the no excuse built so that is probably not good enough. The simple answer is a helicoil but that has me wondering about heat transfer from the plug to the head probably being different in #8 compared to the rest.....try it and if needed colder plug in #8? helicoil all 12? Just try it as is? not really sure what I want to do with this.....
I think you're overthinking it. Helicoil and forget it. Done on thousands of engines with no further thought or issues given after the repair.
In reply to Dusterbd13-michael (Forum Supporter) :
Probably. I woke up stupid early this morning so I wandered out to the shop. There isn't a ton of space left between the valves....probably a coil would be ok. I also put a plug in the hole and torque it to 18N-m with no problem, spec is 16...so it is probably ok as is, the bottom at least 5-10 mm of thread I made from weld is good, its the top 5mm or so that is more than sketchy. I don't know.....so I swung the mill head to 21deg to get ready to cut the exhaust seats while I think.
Heli-coil all 12. It probably doesn't matter, but every time you pull a plug to check tuning, or to change them, you'll think about how you took that step and you'll feel good about it. Then you can pat the head and say "you are never coming off" and smile.
Syscrush said:Heli-coil all 12. It probably doesn't matter, but every time you pull a plug to check tuning, or to change them, you'll think about how you took that step and you'll feel good about it. Then you can pat the head and say "you are never coming off" and smile.
That is a thought I've had......
In reply to mke :
What happens if you have a mangled helix coil at some point?
You've already done the repair and can't go bigger.
Can you weld the first few threads and retap from the backside?
In reply to wvumtnbkr :
*always* retap from the backside.
AngryCorvair (Forum Supporter) said:In reply to wvumtnbkr :
*always* retap from the backside.
In reply to AngryCorvair (Forum Supporter) :
#slowclap
Syscrush said:In reply to Mr_Asa :
If someone were to build the necessary forge/furnace/vacuum setup to do low-pressure lost PLA casting of their own I4 or V8 cylinder head design, print the PLA patterns in pieces at home and assemble/anneal them together, plaster cast and then machine a bespoke head - it would not seem like a more complicated or ambitious project than what we see in this thread. Arguably less.
If I were doing it, I'd likely do a ceramic shell cast rather than plaster. It would still be a bear to clean out the water passages, but I would think that would be easier than manhandling that large a chunk of hot plaster.
I'd need to think about how to figure out how to do the freeze plugs as well. Anyone know what alloy cylinder heads are normally made of?
With something like a WP-25 straight torch (which I don't have) I cold probably get in there to weld it....really hard to see and the rod tends to overheat and melt off dropping in the puddle. I'm leaning toward bottom taping a hole that stops 3-4mm from the chamber and putting in a helicoil. Stock there are about 2mm of threads cleared and just a little more gains space between the seat ODs as well as ensuring the coil is trapped and could really could never end up in the chamber.
As I ponder the idea that the engine may run again there are a lot of little things to take care o, one of which is an ignition timing question that has been in my mind. Dynomation says it doesn't need much timing, like 24 degrees and while that seemed quite low that is what I put into the ECU. A stock QV is like 32 iirc and Wade (ferrari tech buddy) just sent me the TR timing which is...32. I'm a bit higher compression and a bit higher cylinder pressure but 30 feels like the right place to start. The only way to know for sure is the dyno but I'm pretty sure 30 is way closer to right than 24 so I'll make that change and honestly try to remember what else I wanted to fix in the ECU to get ready to run....maybe shot for Jan2, which is the 3rd anniversary of the first run.... and fire 
This graph is state of the art 1980s 8 bit processor and emissions weirdness....other than step 9, that confuses me as its clearly more than 8. The QV map only had 8 which is much easier for an 8 bit processor.
In reply to mke :
Do you happen to do any side work with all those fancy machines?
So it turns out I was either smoking crack or lying or both when I said DM told me 24 degrees timing. DM actually says 33 and that is what I had set in the ECU last time the engine ran. I probably have a bit much in for cranking and idle but it looks 3/4 decent. I have no idea how it got into my head there was any confusion about timing. 
In reply to 88xltranger :
it depends. I've done 1/2 dozen 308 efi manifold conversions and ported a few sets of 308 heads over the years and a few other things like that but generally I tell people you're probably better off hiring someone who's actually allowed into their shop on a regular basis so you know your parts won't take 11 years like my engine
but if there is something specific, shoot me an email mark@gemellocattivo.com
digging through old file I finally found where I thing I use have seem the 24 number. The output tables were right, 32/33 but on the setup page these 20/21 show up....a newer version must have shown the 24. These are some kind of baseline the software uses to calculated but it must be what I saw and had in my mind.
Also it looks like I had been trying to get the engine to stay running and cranked up the idle timing...the old original timing map looks why more right....I'll need to change that back before next run attempt.
pretty colors
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