Dat73z

Got the charge piping out easily co sidering how tight the packaging is. I'm glad I considered serviceability when setting up the runs. No oil in the pipes which is good but I noticed the PS side pipe was rubbing on the core support. I think I'll run a tig bead over that area and reposition the pipe. Unfortunately my coolant bucket is full. Where I live I used to be able to recycle coolant at my local Jiffy lube. Now apparently the county requires me to go to a recycling center which is a city or two over and only open during specific times. Great.

This AM the objective is to get the charge piping and rad out of the car so there's a straight shot to the crank pulley. I'm impressed how much dust the silicone couplers have picked up over a couple thousand miles. Fortunately my wife has been out of the house every morning at 5:30 AM so I have a bit more time in the AM to get things done.

Inspected the undercarriage a bit more before calling it a night. I've always wanted a drill press so I think I'll buy one this weekend and order an aircraft safety wire drill jig. I'd like to drill and safety wire all of the suspension and driveline hardware. I've been keeping this thread mainly focused on the aspects affecting turbo componentry and tuning but there were a lot of other sidebar projects I didn't document this year to turn the shell back into a driver.

Had a couple mins after dinner to pull and examine the crank bolt and washer. Volvo washer is still flat as expected. I've seen the OE washer bow out over time. The crank pulley bolt looks fine. You can see the end was not bottoming out as the zinc coating is still intact/not scratched. The loctite blue might have actually been the high strength red, I can't remember but obviously whatever was on there didn't hold. I think I only applied it at the end, and the threads towards the head don't thread in.

After simmering on this more, I've decided I'll make this my fall project. It's a bit of a bummer because I wanted to get another project car that's been waiting outside into the garage and also do AC fab on the Z here and there. A minor setback but I'll keep trying to do 1 thing per day until the Z is back on the road at least.

@rossman yeah, I'm glad I decided to call a tow and not drive home! The pulley was a tight interference fit on the crank when I installed it. And I did check the bolt, washer, and pulley assembly thickness for the correct length when I chased the threads in the crank to ensure I wasn't bottoming out on the threads. I think I may have documented that earlier in the thread around when I had the volvo crank washer machined. So upon first inspection, no carnage. There were no visible shavings or metal in the oil either but I did take an oil sample and I'm planning to do regular UOIs on this motor. I think I may need to reschedule my dyno date depending on how soon I can get a new KA crank bolt in. I think I want to also check the crank snout for runout, and the crank pulley for any cracks or damage.

@calZ Yeah it's all good though just part of the game, not my first nor last build 😭 So I drained the fluids and they all looked good. I also took an oil sample for analysis. I went to rotate the motor and the crank pulley bolt was barely hanging on, and the crank pulley was just starting to walk off. Good thing I decided not to crank it over after I pulled over. I know for sure the threads were clean, the pulley was torqued to spec, and I used blue loctite as that was the last thing I did right before dropping the motor in with my friend holding the crank stationary. So the next steps are to pull the valve cover and borescope down the timing chain area and see if there's any carnage. 20221021_161339.mp4

Went for a drive over lunch and started hearing some grinding/squealing noises so I clutched in and coasted over to the side of the road. Inspected around the car and didn't see any fluids anywhere so I fired it back up and all sounded normal, started going down the street and hearing some grinding again so I clutched in and as I was coasting to the side of the road the motor stalled out. I pulled the plugs and borescoped the cylinders and all look good, no damage or fluids in the bores. Tonight I'm going to drop fluids and inspect further. Probably start by turning everything over by hand then move on to pulling out the driveline again. Hopefully I just blew the clutch or transmission but we will see.

Picked up breakfast this AM with a lot of boost, afrs mostly in the 11-12s on the gauge and checked the plugs after the drive. Overall the mix looks good, the plugs correspond to what I was seeing on the gauge which is a slightly darker tan than before so slightly richer along with a slightly sootier AFR ring. With the 145MJs the afr ring was just a full ring of grey around so I think a bit more ideal but it's all within where I think they should be. The carbureration feel was a bit soggy so I dropped down the 150 MJs and will see how that feels over lunch.

More tuning going on in the background. Last night I tried upping the MJ's and AC's. I went from 145MJ/170AC to 155MJ/200AC, so roughly for 1 step MJ for 3 steps AC. I'd like to see the response of the main circuit on/off boost. I got the AFR's about the same as before (11-12) to 7k rpms, but didn't have the time to fully test the entire dynamic range, especially when the main circuit tips in. I've read a lot of conflicting information online whether it's better to have larger or smaller MJ's/AC's since you can compensate either way for target AFR. Some people say (for an NA setup) larger AC can delay main circuit tip on, other say opposite. In discussing with my buddy who tunes sidedraft carbs on L's, one benefit is a larger MJ/AC (for an NA setup) can be good for racing, when the fuel level changes during long sweepers so you don't lean out. For blowthrough turbo DCOE cars, one interesting thing I found was to counteract fuel slosh into the MJ stack some tuners and OE's have actually positioned the fuel bowl pressure port directly above the MJ stack to "blow off" any fuel in that area and prevent fuel sloshing into the mains in racing conditions. The area above the MJ stack can also be raised to help, you can see this in the SSS "Devil Z" car, and also OE lotus cars. I never considered that, but it makes sense. Every time I pop off my jet covers, the top of that area is wet with fuel. I'm not entirely sure about any of this, but I'm going after the best response/"feel" for my target AFR's since I mostly drive on the street. I noticed early on, smaller MJ/AC seemed more responsive on/off boost but I figured I'd try again now that I have more of the setup dialed in. I don't mind having different jet settings for the track if I don't need to worry about the full dynamic range.

Maybe someone else with a big block can chime in. It sounds like you don't have any fuel leaks and your timing is good, I assume you've taken a look at all 8 plugs. Your mix could be pig rich in certain areas of the dynamic driving range, I'd recommend an AFR gauge to know for sure. I've been driving my carb turbo L6 a lot of bumper-to-bumper traffic for hours in-city and my fuel mileage is terrible, <10 mpg with as much boost as I can. On the weekends when I cruise on the freeway long-distance it can be in the 20s.

Last night I tried the 40 pump jets. I started by turning the volume all the way in and doing low RPM WOT pulls to test the shot, and back out from there. It seems the setup is happy reducing the volume by a few mm. I do want to try the 45's and possibly 50 pump jets back-to-back on a stable-weather day as well to see the difference, but that would be multiple hours of driving and tuning which is time I don't have currently. This weekend I'll finally go and pick up the 250 needle and seats from my buddy. Both of our schedules just haven't aligned this past month, but as I'm aware that's an issue on long WOT multi-gear pulls I need to get those in before dyno day. It'll be a good excuse to go out for a drive.

It's been a busy week but tonight I attempted raising the float level from 28mm to 27mm. The mains were coming on around 2.5-2.8k rpms so way too early, basically right where I'm cruising at freeway speeds. I lowered the level back down to 28mm. I then swapped the pump jets from 45 to 40s and added a bit more volume back to the shot as a starting point. The AFRs were pegging rich between shifts with a light stumble on/off throttle between full boost 2nd-3rd gear shifts. Tomorrow I'll see how the setup likes the 40 pumps and go from there.

Tonight I spent a few minutes and inspected the exhaust for leaks. I haven't been able to find any. I'm a bit concerned because my bumper chrome has been turning blue/rainbow around the exhaust. I think the fire out the exhaust on quick on/off boost transition at large throttle angles has been due to too large a pump shot. I already turned down the pump volume so I think the next step is one size lower pump jets which I'll try tomorrow. This is one of those things I'm hoping the tuner can investigate but I'll try and dial it in on the street first in case there are more important items to address during the limited dyno time.

This AM some friends wanted to hang out at a local meet so we drove out. My wideband o2 was working most of the time but towards the end it started pegging 10afrs so in the opposite direction from before. I think I need to pull out the entire harness and trace each wire to see what's going on. I initially installed the wideband maybe 7 or 8 yrs or so ago, so it's probably overdue for an inspection. One of my buddies I rolled with was driving a 3.1 Rebello Stroker with triple Mikuni 44s and a 3.9 rear running a bit rich at the transition. On acceleration, the 3.2 turbo at 10psi walks on the 3.1 stroker but man that thing is fast. Off the line he's already gone by the time I'm at full spool but on the freeway the turbo has more legs.

The o2 sensor gauge has been bugging the heck out of me so after lunch I checked out the harness. Everything is crimped/soldered/heatshrunk. I jiggled the whole thing around for a while and didn't find anything loose. Started the car up and the gauge was working again, went for a long drive for errands and worked the entire time. I have no idea what's going on but I guess it works again. I still question the afr values since there was a point when the gauge was intermittently functioning that it would always read high afr values when I knew it was running rich so I'll keep tuning by feel and reading the plugs but at least the afrs give me an idea of the direction for adjustments. 20221015_143242.mp4

For reference here's the Bosch o2 sensor part number. The box looks beat up but the o2 sensor visually looked new. Hopefully someone didn't put a used part in there and do a shady return, I've had that happen before with Autozone/O'Reillys parts.

I cross referenced some part numbers and found a matching wideband o2 sensor at my local autozone. So this AM after dropping my wife off at her appt I picked up the sensor and installed it. The old sensor had some red residue which I wasn't sure if it was rust or fuel additive but it visually did not look carbon fouled at all. So an interesting result after installing the new sensor. Throughout the drive the afrs were reading maybe 1/4 pt lower than what I was seeing before. Including the transition region where sometimes I saw 13afrs was now in the mid high 12s. On the last turn before I got home I was doing some testing and quickly went into boost then back into engine braking. I've been trying to tune this area a bit as I know under certain boost then off boost conditions I will spit fire out the exhaust. The afr gauge then pegged back to 16 and stayed there after the exhaust popping stopped. So I'm back to where I was yesterday. I'm still not sure what's going on but I guess I still don't trust the afr gauge. I'm going to inspect the gauge harness behind the dash and see if I can find anything. 20221015_103954.mp4 20221015_105905.mp4

The o2 sensor was really bugging me so I went for a drive and did a lot of redline pulls with lots of boost. Halfway through the drive the afr gauge started working again and indicated 11-12afrs. Then it started randomly jumping to 16 afrs pegging the lean side of the gauge. I wonder if it's a loose wire or if the o2 sensor is fouled. I think I need to find a way to monitor/log the o2 sensor voltage while I'm driving but I suspect the voltage signal is jumping around. I think I have a used spare o2 sensor somewhere as well.

Managed to get the car up after work this PM. Overall the undercarriage looks good. I couldn't find any signs of exhaust leaks. Everything looks good, and the connector is a locking type. Maybe the next step is to test the inline o2 sensor voltage and see if the o2 sensor itself is bad. Hopefully not because this was one of those parts I waited weeks or months for from the UK earlier this yr due to supply chain delays.

One other thing I'd like to try is downsizing my pump jets from 45 to 40. I have 45, 40, and 35 pump jets to play with. At WOT with the 45s I can sometimes rich stumble the motor for a split second around the transition to the mains. Otherwise the volume is about right for blipping the throttle rev matching downshifts and heel toe. Need a working afr gauge for this as I suspect there is some contribution of fuel being pulled from the accel circuit at high rpms. But generally this is another area I generally tune by feel and response.

@madkaw yeah there was a period of time where I just didn't trust the gauge at all, I was tuning by feel and plug reading. Update on the gauge below again lol. So this morning I went for a hundred mile drive and tried 60 pilots with 1.98mm air orifices. Temps were maybe in the 50s. Vacuum cruise is high 11 and low 12 afrs right before boost threshold. Vacuum engine braking (advance) with the 123 MAP of course leans out the mixture with no load to 13-14afrs for response and economy. The transition is in the 12s and when the mains come on mid 11s to redline. Then my afr gauge pegged 16 and stayed there. I suspect maybe I blew out the o2 sensor or a vband came loose, I'll check it out later today. It was nice just driving and not constantly looking at the gauge. So again another unexpected result, even sizing down the pilots I'm getting the same transition values assuming my gauge is reading correct. The plugs still look good no sign of detonation. Response of course is even better off idle-2k rpms. I also tried some brake boosting and it's a rush but Im getting some boost spikes. Likely I'll need to upsize the vacuum lines from 4 to 6mm and move the MAP closer to the plenum as it's currently behind my dash. Not too worried about the spikes for now as I know the mixture is enrichening along with pulling timing and the motor is fully built. Next steps after fixing the afr gauge is to raise the float level a bit and get into any final checks and tweaks for the dyno. I got through most of my list from a month or so ago, but due to my schedule I'm going to give myself a solid 2 weeks to do some basic maintenance.

Tonight, I compared a 65 pilot jet with ~1.98mm air orifice against a 60 pilot with ~1.32mm air orifice. First impressions are the fuel curves are similar in both. The 65 pilot is more responsive with the larger air, but the 60 pilot seems to have better cruise AFR's and is slightly richer in the transition. Both cruise slightly rich in low 11 AFRs. I think I'll attempt a 60 pilot with ~1.98mm air for response and raise the float level from 28mm to 27mm to tip in the mains sooner and see how that works. What I'm tuning for is the transition region where sometimes I see 13afrs depending on load and gear and of course when you're at freeway cruise and just tipping in with the turbo instantaneously spooling. The reality at this point is unless I had the AFR gauge I don't think I would be trying any of this as the drivability is good and the plugs look ok. So perhaps this is a case of I need to tape over the gauge and stop looking at it.

That looks really good @rossman. Does the car cool at speed? I've seen some ppl louver or cut slots/add rubber flaps to allow the shroud to duct the airflow from the front at standstill and still allow for good air evacuation through the rad at speed

I raised the fuel level last night from 29mm to 28mm, and went for a long drive for errands. The response wasn't as I expected. Actually I didn't really see a response, but maybe I need to do more testing this weekend. At low/no boost I saw a definite trend in the AFR gauge of increasing richness/earlier main onset with higher fuel levels. I'm going to play with the idle jets a bit more next. I read somewhere that, the position, size and diameter of the air orifices on the idle jet should affect the response of the fuel curve similar to the main jet, air and emulsion tube. So basically like a mini main jet stack. At this point I'm just fine tuning around the turbo spool so minor changes to air size/position and 1-to-half sizes on the fuel orifices. I do know my tune has been changing with the weather, and with my life schedule waiting a few days between fine adjustments can show completely different results. The initial jetting was done on 90-107F days, and now I'm driving the car around in 40-50F lower temps. The good thing is I have a solid base tune now to default back to which I'll likely use for the dyno in a couple weeks, so unless there is a definitely improvement in drivability I'd rather err on safety which is more rich and less timing.