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htownz

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About htownz

  • Birthday 10/15/1973

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    Houston, Texas

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  1. Hello everyone, We've been racing my 240Z in 24 Hours of LeMons since 2008 and it's time for a replacement chassis. The current car is a hodge podge of S30/S130/Z31 parts in one box. I am interested in doing a rear subframe swap on the new chassis. Lots of people have done S13/S13/Z32 swaps but those are getting harder to find these days than Z33 (G35) stuff. In the long run I'd like to run a more modern engine and transmission in the car too. Does anyone have info or attempts at doing a Z33 rear subframe swap into an S30?
  2. Hi Guys, I have installed the early style OBX LSD in a 3.90 r200 long nose with Rich Bryant's bolts and washers. I am using early style u joint shafts and can not figure out how to get the flanges to "clip" in. The flanges do not have clips and when I tried adding clips they were to big. Do I need to removed the internal clips from the old carrier? Troy
  3. Hi Guys, I have read through a fair amount of this post. Is there a problem with JohnC's #28 cap to prevent hot spots in the head? I am not sure how JohnC determined #28 to be right. That's not a real common cap to pick up. This post has gone on over 2 years with 18 pages of posts. I have read some of it but by mo means all of it. The LD28 pump looks interesting as well. I currently race a 240Z in The 24 Hours of LeMons and have had a 240Z driver. Back in the later 90's my driver was a 72 with a L26. I live in Houston, TX where it's hot and humid most of the year. The old 240Z with its stock cooling system did okay most of the time. The only time I really had cooling issues were on 90+ degree days sitting still in traffic with the A/C on. I was in college at the time so I was far from wealthy, I not wealthy yet for that matter. The car probably could have used a new radiator but didn't leak so it seemed okay to me at the time. The early 240s just weren't designed with air conditioning and real hot weather in mind. As long as the car was moving and getting decent airflow across the radiator, the car did okay. So I am not sure what everyone is doing with these cars that demands such exotic cooling system modifications. The car I am currently struggling with is the LeMons Z. It's a 73 with a small chamber E88 (like and E31), a C cam on an F54 block. We ported the intake and head. We run 280ZX ignition, 34 degrees total timing and 3-row 280ZX radiator along with a Nissan Motor sports header. I gutted a 180-degree thermostat so it's just a restrictor plate now. A side note, I hope to dyno the car since it's only non-stock part is the header to see what kind of power you can make on stock L-Series parts. I am running an early 240Z harmonic balancer now, which is smaller than the later ones. I opted for that because I was concerned the water pump might be cavitating at high RPMS and the smaller balancer would slow it down. I have done no testing; it's just a concern. We tend to keep the car above 4000 rpms and try to do so for a full tank of gas. Refuel and do it again for up to 8 hours. That's the goal, it just rarely happens that way. This post along with the posts about high compression L-series motors and ignition timing have all collided in my motor. Along our journey down the path of endurance racing a cheap Z we have hit a few speed bumps. Many of which seem to be installer error from working on the car in the middle of the night. So some problems have been self-induced. At this point we have built a second car with a similar motor. Both cars have blown head gaskets. The second car blew its gasket early on in its first race due to an uneven block deck. The engine got swapped out and has not been put back in. The first car has run 4 races and we were fighting engine temps for several races with a lot of head scratching. After our fourth race and a definite head gasket failure, we discovered the gasket sealing rings were burned on #1, #3 & #6. Cylinder #5 is fine. I believe the failure is due to detonation. So I am not exactly sure about the idea of local hot spots on #5 resulting in detonation and head gasket failure. I knew we experienced detonation during the 3rd race, I heard it. I am just not sure for how long or exactly why. We retarded the timing which cut our power and power band (like BRAAP says) but the temp steadied. We were getting unexplained varying timing readings too. We were dealing with several cars at that race too. The first car was not perfect but it was better off then any of the other cars we were dealing with so it probably did not get the time it needed to properly understand and resolve it's issues. It did finish the race though. That race was in New Orleans in June. To say it was hot was an understatement but I do believe we were below 100 degrees that weekend. At high temperatures like that, we expected higher engine temps too so that did not help with analyzing what was going on. I was concerned that the high temps may have caused the air to be thin enough to give us a lean condition, which would promote high engine temps and detonation too. Getting back to the general implication of this thread is detonation occurs from local hot spots in the head that is caused by suspected cooling problems, particularly on cylinder #5. In our case, we are running around 10.5:1 compression which increases the probability of detonation due to tuning. Which gets into issues brought up by BRAAP about timing and head and block combinations. With 34 degrees of total timing, the car just flies. If we go lean, we can have a problem. Those are factors that affect engine temp along with the efficiency and functionality of the cooling system itself. The 280ZX distributor is probably the best stock arrangement we can run but they are old and reliability is questionable. While we do not use the vacuum advance, I wonder if it wasn't moving around a bit and causing our timing problems. After our race in New Orleans, I replaced the distributor with a reman and our power seemed a bit better and our timing readings were more consistent. I still swore we had more hesitation in the mid-5000 RPM range and the car wasn't pulling like it did in the first race. During our 4th race we realized a very odd phenomenon. The car stayed cooler at higher RPMS when the car was run harder. During a test day to check the car out and do some wide band tuning before the 4th race the car seemed to stay cool enough but we did get some variation in temp. It heated up a bit in the slower twistier parts of the track and cooled down under harder accelerating loads. It was leaner in mid-range RPMs than at idle or during high-RPM heavy loads. This occurred more often in the twistsier parts of the track. This is the reverse of what is expected. We did not notice this much until we took some slower laps looking at proper lines around the track. Then we started getting a bit hot on the stock temp gauge. The infrared thermometer showed much lower temps than the stock gauge and we weren't boiling over or anything. The stock gauge was way up though. Our conclusion, either the sending unit or gauge was wrong. Conflicting data makes it real hard to figure out what's going on. We did not run any more sessions that day. Later we replaced the sending unit and installed a second mechanical temp gauge. Ran the car a good while and everything seemed fine. It's like the boat in the driveway; it's always perfect in the driveway. Get to the lake and something seems to have gone south along the way. During the Test & Tune for the race, we are running 25-30 minute sessions with no problems. Once the race started, the engine started getting a bit hot about 40+ minutes into the race. You start finding lots of issues don't occur in a 30-minute sessions when you try and do an enduro. Further disassembly and inspection led us to discover broken ring landings on cylinder #6 and the magic head gasket repair stuff in the crankcase. The Blue Devil not only failed to repair the leaking head gasket, it looks like it got into the oil and damaged the bearings too. Broken ring landings plus the burned sealing ring are both indications of detonation in #6. That was the cylinder that finally burned it's way into the cooling system. We have resurfaced the head. Swapped to a different short block, just because I got a better one. Replaced the rings and bearings and basically rebuilt the motor. We put the motor back in the car last weekend and discovered one of our crappy back up radiators was not functioning so well. It got swapped for another old radiator that appears to be cooling properly. Yesterday we took the car to the track to test it out. We kept the RPMs below 5000 for break-in. With a #20 radiator cap, 3- row 280ZX radiator, 180 degree gutted thermostat, OE style water pump and small early style harmonic balancer we ran a pretty steady 165-170 degrees. We ran about 4-6 30-minute sessions, I didn't count them. In case this matters, we run a hose from the rear of the head to the thermostat housing and no heater core. The only cooling problem we had was when the lower hose got to friendly with the alternator fan and cut the hose. We swapped the hose and everything was fine. Hopefully we have nipped our problems in the butt. Only time will tell.
  4. The simple answer: you will make good, fun power with any of the combinations you asked about. An N42 will have a less compression and may be more managable. The E31 or small chamber E88 are a lot of fun but timing can be an issue which can result in other problems. A larger E88 would have less compression but has smaller valves than the N42. My friends show car 280ZX 2+2 has an N42 on an F54 and it moves pretty good. So an N42 is probably a good option for a driver.
  5. I left out some details, a lot of details, before to try to keep the post a bit shorter. Since inquiring minds want to know, I'll give you more info. Unfortunately, it jumps around and it's loooooonnnnnnnngggggggggggg. Both 240Zs have been running Premium pump gas and I think the 280ZX was the same. All the cars I mentioned have been running the 280ZX distributor. Turns out you can run an 83 on the 79-80 module too. The 240Z with the E31 had Petronix in a 240Z distributor but it burned the module. Turns out, if you leave power to the module with the engine off, and the exciter and pick-up are lined up, it fries itself. Didn't figure that out until the second unit fried itself. So we threw in one of the spare 280ZX distributors and all three cars have been running 280ZX distributors since. The 240Z with the E31, blew it's head gasket at it's first race in New Orleans due to someone getting a bit to happy with the magic gasket removal wheel on the deck of the block. Since then, it's been running a L24. I am not sure what the technical part of why higher compression results in a higher probability of detonation. Just that I have experienced this. Lower compression seems to be less sensitive. With higher compression, the air fuel mixture is more tightly packed. In any case if you light the fuel earlier, it has more time to burn which means you get more complete combustion and power out of it. With a Wideband installed, I have been able to observe the affect of timing changes on the Air Fuel ratio. More timing will be leaner. I am sure there is a limit to this. I saw this pretty clearly on a Chevy V8, don't recall with the L-Series being as obvious. Wideband tuning is still new to me so keep that in mind. As BRAAP has said repeatedly, if you retard timing you are leaving power on the table. We like to run about 35 degrees total timing. No vacuum advance. The more timing we run the happier the car seems to be as long as we don't have detonation. I have not noticed the detonation without the car being under a load. It's more likely at high load and high rpm situations, like 5000+ rpms in 3rd gear on up. My car was experiencing mild detonation during its 3rd race in June in New Orleans. We were basically at sea level but it was hot outside (well into the 90s). The car was running okay but hot. No one else on my team noticed the detonation just the temp gauge going up. We were racing a high-compression Crap Can in 90+ degree weather for 6-8 hours in a day. There are all kinds of variables in this situation. I swapped the radiator with another used back up and it was still running hot. We were just managing it by running the car less aggressively. Then I got in and noticed the detonation. I dialed out some timing, the detonation went away and the engine temp was stable. Unfortunately, it felt like we had a rev limiter around 5500. That was really in the middle of the engines happy place before with it pulling well over 6500. I did notice that at sustained higher rpms the lower radiator hose was flattening at the 90-degree bend near the radiator outlet. I think I noticed this while messing with the timing after the radiator swap. That may have been our temp issue but we had not noticed this problem in the previous two races. It had the same water pump and hoses from the first race, which were new for the first race. The radiator had seemed to be working fine too. I tried trimming the hose and using zip ties to improve the bend. I was at the race and did not have another hose to try at the time. Talking with guys at the parts house yesterday about radiators, hoses and the Blue Devil magic head gasket repair. They said according to Gates, if you are flattening a hose, you have a leak. We were not leaking anything on the ground and did not have any noticeable coolant lose. Maybe the head gasket was compromised and we did not realize it. The motor is currently disassembled and I am putting together another motor. I first noticed the engine temp issue doing a practice/test and tune at Texas World Speedway in May. I don't remember having the wideband in the car. It was the first time I actually drove the car after the engine failure in February at Harris Hill Road between the first and second race and only minutes of run time after the dyno. We left the dyno and went straight to the track that day. We attributed the slight bit of noise we heard at the dyno to valve train. Less than 1 full lap around the track and the noise was worse. As we coasted into the hot pit lane, I realized the engine died. Turned out it seized. Further inspection revealed the incorrectly installed center main resulted in the seized rod bearing next to it. The center main was fine. I did not drive the car during the second race due to transmission followed by clutch issues topped off with a separating strut housing. To me at TWS, the car did not seem to be making power like it did in the first race. I suspected tuning at the time but could not get the car where I thought it should have been. I do not recall any engine changes between the second race and going to TWS. February was a cold race and it was pretty warm at TWS in May. Everyone thought the car ran great in the second race but something was going on at TWS. I could not figure it out. Most of our time was being spent building on the 2nd 240Z and the first car seemed okay. Conclusion, we would figure it out at the track in New Orleans. Additional info, I replaced the coil with an MSD Blaster coil at the track in New Orleans and bypassed the resistor. Car still ran about the same maybe just a bit better and was not pulling like I thought it should at high rpms. The 280ZX with the N47 on the F54 was also having power problems, which they thought was a lean condition due to a fuel delivery problem. I think they were cutting out around 3500 rpms. Sunday, their distributor was changed for another back up and the car ran great until it blew the head gasket. I changed my distributor out after the June race and the car was pulling much better at MSR Houston during the Texas Z Party two weeks later. I still did not feel like we had the power of the first race but the car was better than it was in New Orleans. It was one of the faster cars at the TZP. The temp seemed okay but I did notice it creeping up a bit late in the 20ish minute sessions. So two cars running 280ZX distributors had power problems, which appear to be related to some part of the ignition system contained within the distributor assembly. Both cars ran fine with no load but stumbled under a load. Maybe this is some kind of module problem. I haven’t figured this out yet. During a tuning session before the 4th race, the stock temp gauge showed high engine temps under mild loads. When checked against my infrared, engine temp seemed fine. Under hard loads while using the wideband, the engine temp was fine and our A/F seemed okay. When we started making some milder laps looking at lines around the track was when the temp started going up and we were a bit lean too. We saw increases in engine temp in the twistier parts of the track, which immediately came down during hard loads on wider turns and the straights. The lean condition indicated by the wideband seemed to correspond with the temp going up. More info, we have to run straight water. The gauge exceeded 220 but there were no signs of excess pressure in the system. The infrared temps looked fine. Conclusion bad gauge or sending unit, the gauge is pushing 40 years old now. So I added another half turn on the carbs, if I recall correctly. That was the last session we ran that day. So before the 4th race at MSR Houston in October, we changed the lower radiator hose to a 280Z lower instead of a 280ZX lower which we thought would solve the flattening at the bend in the hose. May have done some additional tuning (I can't recall) and installed a new temp sender and an additional mechanical temp gauge. The two gauges seemed to be about the same but I trusted the mechanical gauge more so maybe the old gauge is still okay. Everyone was happy with the power during practice and for the first 30-40 minutes of racing under green. Then the temp started creeping back about 45 minutes into the race. It would heat up in the slower part of the track but come back down under hard loads again. This is just freakin' baffling! We struggled all day to keep the car under 210 degrees. I wanna say it was still pretty warm in October. The 2nd 240Z running an L24 and 4 row radiator barley saw 140 degrees. The 280ZX did not run the October race. Back to the E88/F54 car: At the end of the day Saturday, the oil looked good, no signs of water. We did not even need to add any oil after 7+ hours of racing. At some point we noticed very small bubbles in the radiator. That was a sign of a leaking head gasket. A compression check showed we had very low compression on 6, lower compression on 3 or 4. We were maybe around 180 psi on the good cylinders where we have been closer to 210 psi on the initial build. We figured the high engine temps had hurt the rings and the head gasket was compromised. We did have to come in and add water at one point in the afternoon cause the motor was not cooling down. We figured it went into the overflow tank. The car stayed cooler under heavier loads than it did under milder loads. We decided to try the Blue Devil instead of changing the head gasket since we figured the head would need to be machined to get a good seal from the head gasket. The gasket only seemed to be mildly compromised. Initially, the Blue Devil seemed to stabilize the engine temp as it idled for well over an hour at a steady 180 degrees. Well, we should have changed the gasket. In the morning I replaced the plugs and changed the lower radiator hose to one with a spring. The car sounded good and we sent it out. Almost immediately under race conditions the temp went up and would not come back down. We parked the car within 15 minutes. I took it out right at the end of the race to take the checker. It seemed fine until we had a Yellow followed by the virtual stop of coming in after the Checker. The temp skyrocketed and I couldn't get it down. It probably hit 240 waiting in line to come off the track. After the race, the oil looked like a milk shake. It looked the Blue Devil even got in the oil and left little bits of grit. Did I mention we should have changed the head gasket Saturday night? So where do compression, ignition, temp and head gaskets collide? I haven't quite figured out the chain of events but they seemed to have come together and had a field day in my motor. There is a chance the FelPro gasket we used after the engine seized did not properly seal. A Stone gasket with Copper Coat will just about glue the head to the block. A FelPro gasket does not appear to benefit from Copper Coat. Back to retarded timing and engine RPMS: As many other people have posted, they want to run 35+ degrees of total timing. Say they set it around 3000 RPM. That would seem fine and all but the timing can/will retard at high RPMS, say 6000 and you will not be running the 35 degrees you set at 3000. That's what I gathered from the info I got. So the retarded the timing should decrease the odds of detonation. So why was I getting detonation? I don't know about all that for sure since I do not have a way to measure timing with the engine under load at high rpms. I can measure A/F with the wideband at high rpms and that seemed fine. We seemed to be getting a good burn. So one issue seems to be that the total timing should be set closer to the red line. I haven't tried this yet. The motor is currently in pieces. It is my understanding that just about all distributors retard timing at some point. Some may be worse than others. A distributorless ignition system is probably more stable and reliable but I have no personal experience with that. The theory on my engine’s failure is this: we experienced detonation for some reason in February. It compromised the sealing rings around the cylinders in the head gasket. Overtime the cylinder combustion slowly burned away at the rest of the gasket. Cylinder 6 got to the cooling system first. This began to pressurize the cooling system. This was where I think our engine temps problems started. It was a slow process so it did not initially seem like a catastrophic failure like the other two cars. The 280ZX literally shot water right out the side of the motor and all over the car. Assuming my head gasket failed due to detonation, what caused the detonation? A carb issue or maybe an igniton issue? This is a massive amount of information that I have struggled to process. It is giving me intellectual indigestion. Enjoy.
  6. I've been racing a 1973 240Z in the 24 Hour of LeMons for just over a year now. The first car has 4 races on it. It has an early E88 (E31 like) head on an F54 2.8 liter flat top block. It should be around 10.5:1 compression. The cam is unknown but some kind of regrind. The head and intake has been ported and gasket matched. SU Carbs The flywheel and balancer have been lightened. I run 280ZX distributor and ignition. I've got an old crappy large tube Nissan Motorsports header with 3" exhaust. 280ZX 5 speed with 3.90 R200 280ZX radiator When running right, it is a bat out of hell. Right before seizing the motor it made a whopping 129 RWHP. We knew something wasn't right and couldn't quite figure it out. Then the motor siezed, make sure all your bearings are in right. We raced the car 20 hours with no oil to one rod bearing due to the center main being upside down. Royal Purple assembly lube is some good stuff. We have had all of kinds of issues, the most recent being a blown head gasket. It looks like we may have had a detonation situation which burned the sealing rings on a couple of cylinders of the head gasket then started on the rest of the gasket. In my opinion/experience, once you start running in the 10+ compression range things seem to be less forgiving. The cooling systems on the early cars are less than impressive. One problem on the L-Series is the ignition system. There are various systems over the years. I think the self-contained HEI type systems on the 79 and up cars are the best. They are still old. So one problem with high compression is the need for stable ignition. According to Rebello, the ignition will retard at high RPM. He says you can see it on a dyno. I'll take his word for it. Aside from ignition, you gotta have correct and reliable fuel delivery. Running a wideband on the track showed a lean midrange condition. The car has happier being run hard than taking it easier. We have had an issue sucking the lower radiator hose flat. May have been an issue with the bend in the lower hose or it may have been an early sign of a leak in the system. That leak in the system being a slight leak in the head gasket. We have added a second 240Z with a similar motor and it blew a had gasket right away due to an uneven block desk We aslo put an N47 on an F54 block in a 280ZX 2+2. It blew a head gasket too once we got a decent distributor in it. Reliable ignition once again was a problem. Aside from all that, I've seen a few cracked balancers as well. Turns out 100 ft-lb ain't really enough. I have been told to ditch the slinger and tighten to 150 ft-lb. In summary, I can tell you a high compression L28 is a blast to race. Unfortunately, I can not attest to it's reliability but I'll keep trying.
  7. Well, it looks like this post is 5 years in the making. I didn't read all the posts but here's my 2 cents. Whether you hit 240 or not, I'd suggest a GM LS series motor with a 6 speed. An LS-with a speed would be pretty damn fast right out of the box and drivable. The options for the LS motor are pretty wide, the new ZR-1/CTS-V are pretty crazy. They are light and make a ton of power bother for their weight and displacement. I don't know if a Z-31 or Z-32 rear can take the kind of power required to try and push a 240Z to such insaneo-sonic levels. Have fun with the aerodynamics too. You could lay the radiator at an angle and suck air in from below the air damn and vent through the hood for cooling and aerodynamics. I don't think a belly pan would be all that hard on a Z but depends on how crazy you get. Good luck.
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