Dat73z

This morning I played with some jetting a bit more and performed a general inspection. I had reseated some gaskets on Carb #3 which was leaking a bit of fuel a few a few weeks ago and it looks completely dry. On tuning, I've observed the surge tank basically amplifies the characteristics of whatever emulsion tube and jets you're using compared to NA. So for example, the f9 emulsion tube which leans the transition and richens the topend was barely doing that NA, but on boost it was doing that a solid pt afr on either end of the afr spectrum. I wanted to richen the transition and lean the top end so I put in f16 tubes back in yesterday and it did exactly that. I have the majority of the curves 11-12afrs across the board so now I'm fine tuning at the transition, which sometimes leans to 13s if I'm high gear, high load, low rpms transitioning/rolling into boost on the progression but not a problem gears 1-3. Simple solution is to drop a gear but when I'm cruising on the freeway (s13 jdm trans/3.5 rear end) I'm at 2-3k rpms in 5th which is right before the mains tip in and the turbo is just starting to spool, so it would be nice to just be able to roll into it in 5th for passing off cruise instead of dropping to 4th. AFRs cruising in 5th are 11-12 so they'll creep into the 13s easily rolling into boost at that rpm range. Perhaps I can raise the fuel level just a bit as well to richen the curves up and lower the tip in rpms...but I also want to stay out of the mains on cruise for economy. But I could also take the easy way out and raise the levels anyways since I'm not exactly driving this car for economy. After months of fine tuning my strategy here is to use the smallest fuel sizes with the largest air bleeds possible. I've found this makes everything more responsive off boost. Since the dcoe type is basically 3 overlapping circuits/fuel curves (idle, main, pump) I may not be able to tune this out without making a compromise elsewhere like richer idle/cruise but this isn't EFI where a few keystrokes can tune it 😄.

Maybe ask to speak to another engineer. Do you have a picture of what you're torquing into? For some reason I'm thinking the floating hub adaptor for the rotor but perhaps I have the wrong idea. I ask because for steel into AL which is constantly heat cycling through the extremes, I always use some form of anti seize to prevent thread galling but that can also change the torque spec. One thing you may also want to consider is drilling and safety wiring all brake and hub hardware. It's a bit more incremental effort on the frontend, but worth it for peace of mind.

Looks great Ross, looking forward to seeing more updates. Do you have anymore pictures of your AC setup? Also not sure if it matters as it all articulates but should the heim joint on the alternator be towards the front of the cast tab?

77ft lbs into aluminum doesn't sound right for a 1/2 sae fastener. I took a quick look online and found this for 6061 T6: https://www.wermac.org/bolts/bolts_bolting-torque-tables_stud-bolts_flange-bolt-up_table4.html I would call Wilwood and ask. I used to be an ME and had lots of books around this. I'm sure if you searched around, you'd find the table for your material. Here's another for 2024 t4: https://www.engineersedge.com/torque_table_sae.htm For something as critical as brakes call the OEM.

This morning I installed my bmc heat shield. As with everything else on this build clearances are ridiculously tight but it clears and works great. The bmc which was scalding hot to the touch after boost sessions is now just warm. The double layer design with an air gap really works well. I also drove over to another local Z guy's shop and found out the cusco front strut brace won't fit. Actually looking at all the aftermarket options I don't think any of them would fit. I think I'll attempt welding something up since I haven't really touched the tig since I made the oil cooler brackets.

I've seen them on ZCD and ebay. Didn't realize this type of failure was so common.

A couple of notes which I found interesting. One byproduct of having the triples enclosed by the surge tank along with all of the charge piping, turbo and air filter is the smell of raw fuel like you'd get with open trumpets is significantly reduced in the garage even after a hot shutdown. My wife welcomes this change. Also I jetted for NA with afrs 11-12 across the board. With the type 2 surge tank, I've noticed the afrs drop as rpms climb. @ 6-7k rpms what was mid-high 12s/low 13s NA is solidly 10afrs on boost. The rpms climb so fast in 2nd and 3rd gear I'm not sure if I want to attempt to pull fuel or wait for the dyno. Cruise @70mph is 11-12afrs.

Realized I haven't updated this thread in a while. I've been continuing to tune and I feel that I've got it 90% of the way there. This thing is crazy. The turbo starts spooling right off idle and the way it picks up speed is insane, and I'm only running 10lbs right now. Drivability is excellent since it's basically building boost right off idle/cruise. Next steps are to get this thing on the dyno and really get it dialed in. I especially want to get the timing curves dyno tuned as I'm running super conservative timing.

I haven't had much time to work on the car this week, but fortunately we're coming up on a long weekend. I was able to finish restoring the Fairlady Z grille which has been sitting for far too long and mount it up to ensure everything cleared the setup. If you ever get a chance to purchase a poor condition JDM grille for cheap thinking you can save some money restoring it- don't do it. Even paying a few hundred more will save you days of labor welding, sanding, painting, plating, and material costs.

Yesterday I got everything dialed in a bit more with the tune. Even with the slight imbalance the engine idles smooth so I think I'm going to wrap up the jetting and work this next couple of days to get the surge tank on and start boosting. Someday in the future when I take things back down for another service I'll play with the shafts and butterflies a bit more. A lot of tinkering but getting closer.

So I got everything back together last night and went for a few long drives. Unfortunately it seems I have some bent plates and shafts. I have the same/close imbalance readings. In conferring with my friend who rebuilds and tunes sidedrafts, a 1-2pt difference on the flow gauge which is what I see isn't really perceptible to the eye. Really delicate stuff I guess so I've ordered some new shafts and plates from Japan. Lots of global delays nowadays due to supply chain and the war in Europe so hopefully I won't be waiting months for that. I've heard horror stories where people have been waiting for arp hardware for more than a year at this point. In the interim since the afrs are good and the cooling system is working well, I'm going to start getting the surge tank back on and boosting for a bit.

Another busy week but I've been putting 30 mins or so per day into the turbo build. My jets came in so I put those in. I wanted to richen up the top end a bit and pull some fuel from the midrange after swapping to f2 emulsion tubes. So 1 size down on the mains, 2 sizes down on the airs. My engine seems to like the f2s more than the f16s I had prior perhaps due to my cam profile/compression ratio/venturi sizing. I also adjusted the valves to ensure airflow between cylinders would be balanced. It was interesting that almost all of the valves had fairly limited/reduced clearances. From some research perhaps this is due to the valves wearing into the seats after a few hundred miles. I'll be sure to check again in a few hundred more miles. Shooting for this weekend to get it all back together.

Tonight I got all carbs sealed and cleaned out. I feel pretty good about the butterfly and shafts having inspected and done the tap test on all but the ultimate test will be running again. I'm going to give them a solid few days for the sealant to cure this time and get them back on later on the week.

Had a break between errands and cleaned another carb. Hope I can get through all 3 today. This one also seems to have a straight throttle shaft/butterflies. I found it interesting that Rebello sealed up some of the carb pin areas with epoxy which makes sense. I believe these areas which are plugged were from manufacturing/drilling. Either way since I have the carbs off for inspection I'm sealing them up as much as I can.

Out of time this morning but I got one carb fully cleaned and back together. Just some quick reference shots of how much loctite 567 I used for sealing. Since I'm still waiting for some jets I'm going to let these fully cure out for 2 days or so before letting them see fuel. However long it takes for my jets to come in.

This morning I took a closer look at the carbs. Other than the side mounting areas where it was evident loctite 567 got by, everything looks as it should for a couple hours on the dyno and a few hundred street miles. Just needs some cleanup. Also as a reference for anyone doing this, the locking studs and nuts can also weep a bit of fuel as seen in the pic below. I'm going to seal these as well with a more careful application of loctite 567. I think all sidedraft dcoe style carbs would slightly leak in these areas under boost given the retaining design. Now I get to do this 3x. The joys of triple carbs/itbs...

Today my wife and I decided to check out car week by Laguna Seca and Carmel. Lots of amazing cars out there and builds. When I got back in I decided to get back into the build. After driving around for a bit more I still have the imbalance so I pulled off carb #2 which had the largest imbalance pictured above. With the way I set up my fuel system, heat shield, and throttle cable the carbs come off in a matter of minutes. If there is a bent shaft or butterfly I'm not seeing it. It seems there's a bunch of gunk in the barrels of what looks like loctite 567 from sealing the side ports where fuel was leaking. I'm going to clean out the barrels and manifold with carb cleaner, check for leaks, and see if things get back in balance. Edit: thinking about it more I really should get everything white glove clean. I'm glad I sealed the carbs but it's apparent they were in fact leaking badly from the factory at those side threaded areas since the casting there is paper thin and loctite 567 made it into the bores. Out of time to tonight but I'll get an early start on it tom AM

I drove the car around quite a bit yesterday evening. Things are running much better. Lots of horn honks and waves, hopefully I can meet more local Datsun people again soon. Unfortunately it seems I may have tweaked the throttle shafts a bit when setting up WOT or something. The carbs were easily balancing before across all cylinders but now on carbs 2 and 3 I get a bit of difference across the barrels on the same carb. I checked the plate positions up top and they are in-line across all the first progression holes. I swapped the plugs for fresh ones and will investigate further. The last time I had to deal with this was on a set of well used triple webers which I ended up rebuilding with new shafts/plates. Hopefully it doesn't get to that point but I've gone through all this before on sidedrafts so nothing new just annoying.

I went on a nice, long test drive after lunch. The car is running cooler and the heatshield is effective enough where the bottom of the carb feels just warm instead of boiling hot after high speed running. I can feel the coolant siphoning through the turbo coolant lines after shutdown as well. It seems everything is working much better so I'll keep shaking things down tonight.

I get today off but as with most days off things get busy... I got up early and was able to get everything fully reassembled before heading out. Going to change the oil/filter and start bleeding the cooling system hopefully hit the road in the PM or evening if things don't get too busy.

This evening I'm starting in on sealing the carbs and final assembly to hit the road again tomorrow. A critical element is sealing the carbs at the side mounting areas. I think my Mikuni 44s had these same casting areas but my Webers did not. On the OER 47s all 3 of my carbs leak fuel on the lower threaded hole due to how thin the casting is in that area. Lots of fine detail work now but it needs to get done.

And a quick reference picture from a lower side elevation. The geometry for the additional pieces looks like they will be tricky and I want to minimize gaps. I think the strategy will be to start with one large paper template as to produce the pieces from single sheets and design the folds such that they overlap. Mounting such that the additional shields don't rattle will be challenging as well so I'll need to carefully think through the bracketry for that.

@rossman I may need to go down that path as well. I only know one other person locally who has a high HP stroker L turbo and they recommended running no hood lol. That's not an option for me but I've been running with my hood cracked this entire time to evacuate the rising hot air off the turbo...I may need to go vented hood as you suggested but I also have some concepts in my mind for forced airflow via ducted fans using something like this https://www.revotec.com/acatalog/Hose-Adapters-1.html This AM I started measuring out the other pieces of the multi piece heatshield concept. I think I want to attempt to box in the turbo hot side in the teal and provide additional shielding for the fuel lines in the orange. I think this will come later after I get back on the road this weekend as I want to get back to tuning first

It's been another busy week but I got the center section of the heatshield done. I didn't take too many pictures as I've had limited time this week but rest assured working the material was a massive pita. I'm just waiting on some grub screws which should come in tomorrow. Everything will come off one more time to acetone wipe off the sharpie marks and gas. Then I will seal all the hardware to the carbs with loctite 567 to prevent fuel leaks under boost. Fortunately I get Friday off so I'll dedicate that day to driving and shaking down the revised setup. I'm hoping all of these cooling and heat shielding upgrades have improved the turbo heat situation.

I had maybe 30 mins tonight so I installed the riv nuts on the heat shield brackets. Hopefully tomorrow evening I can start transferring the pattern to the heatshield material.