Jeff G 78

You are on the right track. We will probably install a wideband O2 sensor to see what's going on. It doesn't count against us as it's considered information only and doesn't affect the performance. One suggestion I got from a fellow CC racer is that we are cooking the fuel due to the use of the stock fuel rail which is bolted to the head in the original four locations. All of that head heat is transmitted right to the metal rail and is then captured by the OE heat protecting wrap. I'm sure the rail was probably too hot to touch, so it makes sense. We don't run any of the OE emissions equipment. The EGR and air pump are gone as are the rest of the stuff. The "spillover" theory that a racer told me makes the most sense. It's when the car goes rich mid-turn due to high float heights and then sputters off the corners until the plugs dry off. I will talk to Steve and Bruce at ZT and see what they say. Our biggest problem is that even at night when the car ran damn near perfect and we turned our fasted race lap, we were STILL 12 seconds off the leader's best lap and the slowest "fastest lap" of any car. Granted, there was only a 10% spread through the field, but we are still too slow. I'm thinking that we could improve the overall running and eliminate the lost laps due to vapor lock, but it won't be enough to even be a mid-pack car in lap times. We need more HP. We can either try to eek out what we can with the L26, swap in a L28ET, or go radical and swap a V8 or other motor in the car. I would really rather not go the V8 route, but I am not against a turbo swap. After a quick CL search, I found a <100k turbo motor for $500. I'd rather find a whole ZX Turbo, but those aren't exactly common in the rust belt. Thoughts???

Yes, that's what we run. We still use the old RT-615, not the new RT-615K.

Dave, I need to research the rules and see how much a turbo is worth to the budget. Then I need to spend the winter searching CL and ebay ads for cheap Z cars. ChumpCar uses a system called AIV or Average Internet Value. We have to produce ten ads for cars like ours and the average ASKING price is your AIV. The cars must run to qualify and they must be the same make, model and option list. For old cars like the Z, they allow us to use all S30's even though they might have different engine sizes than the car we run. For this race, I came up with an AIV of $415. That means I could have $85 worth of mods for a $500 max value. Keep in mind that COST never factor into AIV. It's all about VALUE. In other words, if I buy a Rebello stroker motor from a friend for $85, it's not going to fly. They have value assigned to many common upgrades. Have aftermarket bars? They are worth $50 each. Springs, camber plates, and other mods have similar minimum VALUES assigned. I say minimum because the value can go up if they are more than cheap aftermarket parts. Chinese ebay coilovers are worth far less than real race coilovers, for example. I have never seen turbo values listed, but a junkyard turbo motor can be had for what, $150? That means I'd have to get my AIV down to roughly $350.

No, we didn't try anything with the hood this time. We did try it in the past, but that was before any of the recent changes. We don't have a hood latch and we run hood pins, so we'd have to remove it and we have lights mounted to the front of the hood, so we'd have to unhook the wiring to those as well. We did consider taking a cutoff wheel to the hood and cutting a big hole over the carbs. I'm pretty sure I still have a vented '78 hood, so we might paint that one up and use it instead for future races.

Rich? Hmmm, I always thought that hot exhaust meant lean. Makes sense, I guess. And yes, we are still using the stock rail. I guess it's time to ditch that too. It's still bolted to the head in the stock four locations.

I forgot to discuss a few more details about the running issues. One thing we noticed is that during normal operation, our temp gauge reads about 180F, but at track speeds, it reads only about 130F. This is with a brand new 180F thermostat. The engine is clearly getting plenty warm if the exhaust manifold is glowing red, but why is the water temp so low? To try to help the vapor lock issues, I made a heat shield that protects the fuel bowls from the exhaust heat, but it didn't help at all. When we had our high RPM issues, I replaced the bowl to nozzle hoses with stiffer clear Tygon hose with no improvement. At about 5am, I had a nice discussion with a fellow racer who knows old Japanese carb cars very well. He said that our stumble exiting corners is due to "spill over", a condition where the floats are set too high and the fuel is forced up the nozzles in long corners. The car goes rich in the corner and the plugs get wet. It takes several seconds for the plugs to dry and fire properly again causing the acceleration stumble after a hard corner. He went on to say that to lower the floats, I need to drill the jets bigger to allow fuel to flow into the bowls faster to avoid the high RPM starvation. Raising the floats like I did fixes one problem, but causes another. It was a good trade-off, but drilling the jets out and lowering the floats a bit should let it rev as well as fix the stumble. We will make a more permanent bracket for the fuel pump (the current one is really chumpy as it was made in 10 minutes from 22 gauge sheet metal), but we still haven't figured out how to fix the fuel temp issues. The return system doesn't help the fuel that's sitting in the bowls. Why is the exhaust manifold so hot? Is that normal? Hot normally means lean, but we already have SM needles and have fattened it up by raising the floats. Even when running perfectly, we really need more power, so we might have to look at a L28 or even a turbo L28. We just have to do it on a shoestring budget to stay legal.

OK, be prepared for a long post... We went out on the track Friday morning for practice and the car immediately exhibited the same issues as before. We pinched off the return line with no improvement and kept trying different things to no avail. At one point, we went to restart the car and the battery was dead. We checked voltage and it appeared the alternator was not working. We had a new one with us, so we installed it with no improvement. We then swapped the voltage regulator with no luck before we started tracing back every wire in the car. The problem turned out to be a missing wire that was removed during wiring cleanup. A teammate had inadvertently removed the wire that powers the alternator! With the wire back in place, we were once again charging and we figured that our high RPM issue might have been caused by low voltage to the coil. It was now 4pm and we still had to go through tech, so daytime practice was over and we had very little track time. We got through tech and prepared the car for night practice which started at 7:30pm. The car ran way better and we thought we had been chasing fuel issues when it was really low voltage this time. We swapped tires and did the final checks Friday night before we hit the sack. Saturday morning came and we took the green flag at 10am. The weather was beautiful, and the air was still cool. There is a 2 hour driver stint limit and with our new tank, we should be able to run that long, but after 1.5 hours, the driver radioed in saying he needed fuel. The car took only 10 gallons to fill and we were back on the track. He said that the car ran well and made power to 6500 RPM, but it stumbled off turn 13, the tight right-hander leading to the front straight. The second driver again went 1.5 hours and used 10 gallons of fuel before the car began to backfire on decel and sputter out of the turns. By now, it was a little after 1pm and the temperature was up into the high 70's with bright sun. The car began running worse and worse on the straights going back to its old habits of not revving past 5000 RPM. This time, when the driver came into the pits for fuel and stopped at the beginning of pit road to get his timer, the car died(they put a magnetic timer on the roof of every car entering the pits to make sure you spend a full 5 minutes in the pits for fuel stops). We pushed the car to our pit stall and fueled it up. When he tried to restart, it had all the signs of vapor lock. The car tried and tried to start, but wouldn't keep running. We lost almost 15 minutes before we finally got it going. We cycled through the drivers and it kept running worse and worse through the day. At every fuel stop, it would refuse to restart hot and we kept losing time. Our fuel pump was struggling to prime and fuel pressure was sometimes good and other times not during engine restarts. We tried every combination of return open and closed. We then decided to go back to the paddock and install the mechanical pump in series with the electric pump. We lost a lot of time and when we finished, it made the problem worse, not better. At was now 5pm and the race was checkered for a 1 hour safety break to rotate corner workers. After a 15 minute drivers meeting, we got busy making changes. We removed the electric fuel pump and made a bracket to drop it down a foot lower to be right at the height of the bottom of the fuel tank. We were sure that the pump couldn't lift the fuel to prime once we got low on fuel and sucked some air. We also removed the mechanical pump again and we were ready for the 6pm restart. I finally got my turn at the wheel after the restart and the car ran great other than the stumble down the front straight and back straight after right hand turns. All was fine for 20 laps of so until a full course caution and the safety truck came out. The truck was going very slowly and we came to a full stop as we waited for a tow truck to extract a car from the mud. As soon as we stopped, the car died on me and wouldn't restart. I was dead in the center of the track with classic vapor lock symptoms. I tried for several minutes to refire it on the track, but it wouldn't catch and I had to be towed back in. After we iced the carbs and it cooled a bit, it fired back up and I was back on the track. It ran great other than the two stumble spots. As my stint finished, it was just getting dark out. It is now 7:40pm and it's dark out. We are in 50th position out of 75 teams. The temps began to drop right away and the car ran better and better. We never missed a beat over night and by sunrise we had climbed to 39th place. The stumbles went away completely by the time I got my next stint at 3am and the car was running perfectly. It made power to 6500 and was able to keep up with most of the other cars. One thing that showed up in the night was that when we came into the pits and popped the hood, the exhaust manifold was always glowing BRIGHT red. I assume this was happening all race and we could only see it at night, but I can't say for sure. Now that we lowered the pump, we never had any priming issues and we could use more of the tanks capacity. Sunrise over Northeast Ohio and the race was stopped for a quick drivers meeting. Overnight was some of the worst driving I have ever witnessed on a racetrack. There were cars going off everywhere and in the first 17 hours of the race, we had 6 rollovers!!! All teams got a stern warning to stop driving like asshats and we were back to racing. We kept gaining spots and we were in 37th place at 8:45am. The next to last driver got in the car and ran his 1:45 stint. He came in at 9:25 and said that it was starting to stumble more and not rev all the way. He also said that the tires were really losing grip and that I'd have to go longer on gas than anyone else was able to do and just bring it home with what I had to work with. I got in the car to finish the final 2 hours of the race at 10:30am. The car was running even better than it did overnight and unlike overnight, I had a lot of clear track to work with. It was the best 30 minutes I have ever had on a race track. I had several close calls though. After only a few laps on the track, I entered Oak Tree, a banked left hander, in the outside lane and I there was a very fast V8 inside of me. I heard his tires howling and I knew he wasn't going to hold his line. He slid across the track and I was prepared to get hit. He nailed me in the rear bumper and I quickly corrected and saved it. He got the black flag the next time by the start finish line. After another few laps, three other cars spun right in front of me and I was always able to avoid them as they blocked my path. Unfortunately, I lost communication with my crew only a few minutes into my stint, so I had no idea how long I had been in the car or how much time was left in the race. Not knowing how long I had been in the car, it started backfiring on decal and really stumbling coming out of corners. This is exactly what it does when getting low on fuel. With no pit communication, I ducked into the pits to get fuel. This was the wrong thing to do! As soon as I cam to a stop at our stall, the car died. I asked how long I had been out and the answer was only 45 minutes! Oops! There is no way I was low on fuel, so the problem was simply that the car running poorly due to the hot weather and ongoing fuel issues. The car refused to restart for several minutes. I got back on the track with my communication working again and I just drove what I had and worked around the poor running. With my poor decision to stop, I lost 2 positions. I ran the car as hard as I could and took the checkers after 25:25:25. We finished in 30th place and logged 698 laps and close to 1400 miles. In the awards ceremony, they again scolded the field for terrible driving and said that nearly every car in the race was damaged. The ChumpCar staff had talked it over after the race and asked the corner workers if there were any cars that didn't have any damage and were never called out for going off track or running into anybody else. They concluded that only one car ran a truly clean race and they announced the #46 Broke Racing Effluence Datsun as the "Mr. Clean" award winner. It was really cool getting another award. Last year, we won an award for the best looking car. After the race, we spoke with many teams who told us how pleased they were with our driving. We took the oldest car in the field by a decade and completed the longest endurance race ever. We were never fast on the straights, but I'd say we have the handling dialed in near perfect. We started the race on used 195/60R14 Falken tires that ran our first 24 hour race two years ago. They ran 185 laps in that race and 698 laps in this race and they are still not to the wear bars and they have worn perfectly evenly across the tread. The Porterfield R4-E brake pads have now run 14+ hours at GingerMan, two track days, and 25+ hours at Nelson Ledges. We never even replaced the brake rotors that were on the car when we bought it two years ago. We were ecstatic with our race overall and we will figure out and fix the issues before next season. Thanks to all who helped us!

I'm WAY too tired to go into the details, but the car ran terrible at times and great at times. In 25 hours, 25 minutes and 25 seconds (25:25:25), we completed 698 laps for a total of just under 1400 miles! We finished 30th out of 75 entries and had a great time. The handling was amazing and the motor ran great at night when it was cold. We had terrible vapor lock and other heat related fuel issues in the heat of the day. Thanks to all who helped and I promise to give a full race report with the symptoms and fixes once I get a shower and some sleep. I haven't done either since Thursday. BTW, we won the Mr. Clean award for the cleanest driving. The Datsun only has one scuff in the fender and a chunk out of the front bumper. Both were caused by other drivers sliding into us in the middle of the night.

I want to thank everybody for your help and support. The Z is on its way to the race and I am just awaiting another teammate with the camper to arrive at my house. We should roll into Nelson Ledges around 11pm tonight and we'll know tomorrow if it runs right. I won't likely have any internet signal, but if I do, I'll let everyone know how it goes tomorrow. The race starts at 10am Saturday and finishes at 12:30pm on Sunday. Other than an hour safety break to rotate corner workers, we go straight through for a total race time of 25:25:25. Fingers crossed...

Here would be my short list of changes: Same body shape and design, but with slight tweaks for better aerodynamics to avoid exhaust fumes and front end lift Better spindle pin design so there wouldn't need to be "right of passage" for future owners Better rust protection Better differential front mount design Timing chain tensioner that can't pop out of position when the chain isn't wedged Better dash pad material that wouldn't crack in a few years

Hey Captain, you aren't THAT far away. The race is at Nelson Ledges in NE Ohio near the PA line which is about 5.5 hours from Philly. Yes, we have a Friday test day at the track to prove out our fixes. I raised the floats a bit, but didn't want to raise them way above the FSM specs. According to Bruce, the fuel should be 1/16" below the nozzle in the carbs when tuned. I raised the floats several mm, but still couldn't get them near 1/16". If needed, I'll raise them some more at the track. I have a question for those of you who have performance cams. My cam specs are .450 lift, 260/260 duration. What kind of vacuum do you get at idle? I'm getting about 13" hg which would be low for a stock cam, but I can't recall what it should be with that cam.

Intake system is the stock '72 orange airbox. On the cam timing, keep in mind that this engine ran this way before and after a rebuild and with two different cams. I have rebuilt plenty of L6 engines, so I'm sure that it is correct. I matched both the bright links on the chain and verified everything physically before and after assembly. I agree that not having a temp gauge isn't good madkaw and I should have know better. For those who haven't followed my journey, this car was purchased as a complete basket case for $350 and was built from the ground up with virtually no money in 9 weeks. Every mechanical system on the car was either shot or screwed with by previous owners. The 9 week build included the car being gone for 2 weeks getting a cage installed. LeMons and ChumpCar World Series isn't like any other form of racing. It's all about racing real $500 cars, not who can spend the most money. Rather than stiff springs, race shocks and adjustable suspension, the stock springs were cut, the 25(?) year old dampers were kept, and suspension tuning was done with tall spring aid jounce bumpers and LCA pivot point relocations. Rather than rebuilding the engine, we tore it down to inspect and clean it and reassembled it with new gaskets only. The body was painted with Rustoleum applied with rollers and so on. Almost all of the parts that we did replace before the first race came from my vast stash of used parts. Gutting the thermostat is a common LeMons practice that *normally* works fine. The car has run well at times when it gets enough fuel, so low engine water temp was never considered as a cause for any of the running issues we've experienced. After the first few races and lots of track days, we have replaced a few things and recently rebuilt the engine, but for the most part, it's still nothing more that a $500 race car. Take a look at the build photos in this link http://www.facebook.com/media/set/?set=a.105973052763868.11825.105972559430584 to see what we started with. Click on the first pic and scroll through them so you get the captions as well.

Correct on the pressure reading. I was thinking the same thing on the A/F without a thermostat. It really surprised me that the temp stayed so cold last year on the track. We ran a 14.5 hour race at 80F ambient and the gauge barely moved off 120F. The thermostat was in place with the valve itself removed. I would have sworn that it would have enough restriction to allow the engine to get up to temp. I guess I learned a tough lesson... I'll let everybody know how today goes. Thanks to all who have helped!!!

In for the night. It was a long day, but we made some progress, I think. Per my last note, the 4 - 7 psi pump is in place and working. According to my crappy little gauge, it is putting out about 3.5 psi with no load. I need to find a real gauge and a long hose to see what I'm getting on the track. I found the issue with the temp and oil pressure gauge. My teammate was cleaning up wiring and cut a power wire that fed them. Interestingly, the temp gauge does work. That means that for the past two years the temp has never gotten above 130F even when it was 80F ambient. With the thermostat in place, the temp gauge came up to just below the mid point just running it in the garage. I bought a 180F fail safe gauge BTW made by motorad. I think that's the same brand that MSA sold me when I bought one for my 280 a few years back. I still need to tune the carbs with the floats adjusted and the thermostat in place. I took the front fuel filter out to install the regulator and I then put it back in when I had to remove the regulator. It was the easiest way to make the hoses that I had work out. Prior to using the electric pump, the filter was always about 1/2 full, but now it's completely full of fuel. I guess that's a good sign that I have more flow. The mechanical pump is gone and we installed a block off plate. I still have the return line in use right now, but I will keep an eye on the pressure and block it if needed. I am still using the OE 260 fuel rail that is similar to a 280 rail with a return loop. If I quit using the return, I will need to come up with a safe way of blocking the hose. I guess I could install the regulator in it that won't flow anything. Tomorrow I will tune the carbs and check timing, compression, leakdown, vacuum, etc. At least I don't have any more leaks from the water neck. The helicoil did the trick. It's always good to have a M8x1.25 kit handy.

Quick update... No, the race isn't until NEXT weekend. This weekend is all about getting everything diagnosed and the pump installed. Facet pump is installed as WAS the Spectre regulator. Pump works fine, but the regulator appears to not work. With the regulator in place, no fuel flows past it. With it gone, the pump flows properly. The regulator has a In and Out marked which were checked. The carb inlets were clean and the float heights were fine per the FSM. I haven't tuned it yet due to yet another several issues. We installed a thermostat and one of the bolts felt soft upon tightening. Sure enough, it leaked and when removed, the housing was partially stripped. A Helicoil solved that problem and the leak is gone. Next, we readjusted the valves. Most were fine, but a few needed some minor adjusting after the track day and a fresh valve job. The next issue is that we started it up and it ran great, except we have no oil pressure or temp showing on the gauges. Before, the temp would climb to 120 and the oil pressure worked just a few days ago. They are both completely dead now. I can't see anything wrong, so now I'm off to check the archives for how to check the gauges. The cam lobes have fresh oil, so I know it's just the gauges. Everything is hooked up as it was a few days ago when they worked. We haven't made near the progress I had hoped today, but we still have time to get it done.

Wish me luck tomorrow. I will go through the list and see what I can do to fix the issue. I was able to find a Spectre regulator just like the one beermanpete showed earlier in this thread. I wasn't able to find a gauge yet, but I do have the little tiny 0-10 psi gauge that I can use until I find a bigger one. I will have lots of things to check and swap tomorrow and hopefully I find SOMETHING that gives me hope that the problem is fixed. Since I found a regulator, I will use the 4-7 psi pump and I have a new Bosch FI canister fuel filter from my '78 that I can use before the pump. It should provide good flow and have lots of filter media. Should I try to keep the return to start with and run the regulator in the return line? What about the mechanical pump - should I remove it right away, or keep it in series to start with?

Bruce suggested I talk to Steve in the shop, but nobody has been answering the shop number when I call. I'll try again tomorrow.

The two Facet pump numbers are 610-1077 and 610-1078. They are Facet pumps, but also have Napa branding on them.

I never heard back from Black Gold Man on the RX7 pump, so I stopped today at Napa and bought both Facet pumps. I am still confused about which one is the better choice. From what I understand, the SU's want 3 - 4 psi right? The Facet pumps are 1.5 - 4 psi and 4 - 7 psi. The higher pressure pump flows about 10% more as well. So what exactly does a pump's range mean? Is the 1.5 - 4 pump going to be too low of pressure? I tried but failed to find a regulator locally, but I got a lead from the guy at Napa of a race shop in town that might have them. I'll check tomorrow. If I find a regulator, the higher pressure Facet pump should be better and then I can adjust the pressure down, but if I don't find anything, which should I use?

Steve, My plan is to return the needles to the correct heights first since that's the way we ran it Sunday prior to my experimenting. I will then CHECK the fuel height in the nozzles. If they are WAY off, I might have found a cause, but I doubt they will be off by much. I made myself a float height gauge block last year and that's how I set the levels. My SU's are from a '72 so they have different float heights front to back. Here is the block I made per the FSM. It makes setting and checking the floats WAY easier. Captain, Unfortunately, it will be fire drill time at the track, but with the right planning, I will have a pile of parts to try and a specific order in which to try them. If NOTHING fixes the problem, then we simply become a rolling chicane for 25.5 hours and I will be very bummed. BTW, we have also tried different wires, cap/rotor, and plugs. The spark we have is very strong. When we did a compression check and I pulled the coil wire, the spark was jumping well over an inch from the coil wire to the body.

Hey Blue, Is all that work being done on your 280, or a different Z? We need pics!

We ran a 4 panel wink. It might have been about 30" long.

I do have a block off plate on a spare 280 head, so I'm good there. I might leave the mechanical pump in place for now though until I get an idea of what's going on. As for the temp gauge, I'll have to diagnose it if it still doesn't work. The sensor and gauge came from a '75 that I parted out. The gauge worked 20 years ago when I quit driving it. :-) Oh yeah, we always have an extinguisher in the car and ready to use.

How have you been Ron? I hope you've had so time to work on the Z. I'd love to borrow your module. My dizzy is working great and hopefully the module is as well, but it would be nice to rule them out just in case.

I'll add it to the list Zed Head. Maybe Geezer will loan me his module so I can try it if needed.