Jeff G 78

Thanks all for the continued ideas. I got the car back late last night and I'll start trying all of the great suggestions you have given me. My plan is to do all of the most likely fixes. From there, I'll prepare to do others at the track in case the not-so-likely becomes the likely once I hit the track. I have one week to get the parts needed and installed before I leave for my race. Here's my game plan: Remove the mechanical pump and install an electric pump near the tank with a single quality filter. Install a fuel pressure gauge and position it to be in view from the driver's seat for testing. Check all fuel lines and hoses for possible leak paths. Check carb hoses for signs of kinking. Recheck carb inlet screens and float valves for debris Install a new quality thermostat. Recheck the valve clearances. Perform vacuum, compression, and leakdown tests on engine. Install an additional ground strap between the engine and body. Check fuel pressure w/return. Block fuel return system. Recheck fuel pressure w/o return. Set the SM needles back to the properl height. Retune/synchronize carbs. Adjust the fuel level in the bowls per Bruce's method. (set fuel level to 1/16" below top of nozzles) Check timing at high RPM. If nothing jumps out as a smoking gun, I will *try* to get to a dyno this weekend. More than likely, I will not have the time, so we will leave a day early and pay for the Friday track day at Nelson Ledges to test the changes. Assuming it runs well without hitting the 5,000 RPM wall, I will remove the excess fuel line and reposition the fuel pressure gauge to underhood. If it still falls on its face and none of the other ideas help, I will swear and pout for a bit and then have a really crappy weekend playing rolling chicane for 25.5 hours. Am I missing any of the ideas? Hey BGM, did you locate the RX7 pump? If not, I'll buy the facet pump tonight.

Ray, this is the one we use. I mis-spoke before, we got the 14" mirror, not the 17" one. From the driver's seat, I can clearly see directly behind me and all the way around to about 10' straight out from the RH door. The wink didn't have near the range and it was very distracting. http://www.ioportracing.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=L22534-37&Category_Code=MIR

We had a wink in the race car for a few years and we just switched to a 17" panoramic mirror. HUGE improvement! The viewing angle is far superior and now we can actually see everything behind us on the track.

madkaw, I will look closely at the hoses, thanks. beermanpete, I thought about the dual filters, but have never tried to run just one. I haven't looked at the timing at high rpm, but it's dead stable at 2500 where I checked the total advance. I'll check at higher rpm too. I ran a holley red and a regulator just like that on a '72 with triple Webers. I called around and can't find anything local. I do like the idea of higher pressure and flow with a regulator adjusting it back down to the exact pressure needed. pizzaman, this tank hasn't been treated. The first tank was and yes, the inlet was clogged with POR. That was one of the reasons for the tank swap. This tank is clean and free flowing.

OK, thanks all. I will add a (quality) thermostat back in and see if the temp gauge actually does work. Bill, YES, please try to find the pump and let me know if you find it. I will be buying a pump tomorrow after work if you don't find it. Randalla, no, the tank is good and we ran it with 4, 12 and 16 gallons of gas in that order with no change. Steve, I agree that a wide band work be the best way, but we just don't have time to add one in time. We are thinking about going to a dyno this weekend (if we can get in) though to check and tune. I might also try the OE needles, but we did have the problem with and without the SM needles. No other carbs available and no old hoses to try. I think the old hoses cracked when I removed them. Gotta run and go pick up the Z from a race shop an hour away, but thanks all!

The T stat is gutted simply to avoid a stuck thermostat and an overheating condition in race conditions. I can certainly put one back in. That was on my radar as a possible problem, but I figured it wouldn't be an instantaneous cutout, but rather a general running problem. As for the plugs, I didn't have a chance to shut the car off during a stumble to check them at that moment, but after a session and cool down lap, the plugs are a perfect light tan color. I can't say if it bogged prior to hitting the wall, but I don't believe so. I think it's fine and then terrible. I am running new hoses from Bruce. When I installed them, I made sure they were straight and they show no signs of kinking, but how can I tell? Is there any evidence to look for of them collapsing? Mitchell, thanks for the pump suggestion, but I need to find something local due to time constraints and the only thing I have found is a Facet 1.5 - 4 psi cube pump from Napa. I just talked to Bruce and he thinks that will work fine. The low end of the pressure range scared me a bit, but ??? They also have a 4 - 7 psi Facet cube pump, but Bruce is worried that the pressure will puke fuel out the vents. Thanks all for the help and keep the suggestions coming. IF I ever fix the problem, I'll be sure to report my findings.

Bruce, the needle adjustment was a trackside test just to see what it would do. I didn't really expect it to fix anything, but I wanted to see what direction it took us. As for electrical vs. fuel, I certainly agree, but I have tried three different distributors and three different coils. In every combination, the symptoms didn't change at all. I will add another ground strap, but I don't think that is a problem either. Randalla, I have read about fuel lines sucking air elsewhere as well. All of the hoses are new and the hard lines are in good condition, but I will verify once I get a big gauge connected that I can watch. You must be talking about Guernsey Farms Dairy. I live within walking distance of it and go there often in the summer for ice cream. What electric pump does everybody recommend? And don't say get an RX7 pump from a JY because I haven't seen a JY RX7 in these parts for decades. I'll probably look for a 3 -4 psi Facet cube pump, but I want to find something local if possible to save time.

Update: I got feedback from another driver and she said that when she drove the car (prior to my needle test), the car ran fine for the first few laps and then wouldn't rev past 5k. After her session, I raised the needles and re-balanced the carbs and it was the next driver who reported the issue occurring right away and at 4k rather than 5k.

Bruce, I have a quick question. What is the ID of the fuel hoses between the bowls and chokes? I need to buy some clear hose at lunch today to double check the fuel height in the bowls.

Hey Bruce, I just asked my teammate (I never drove the car on Sunday) if the car accelerated OK when he first pulled onto the track and he said no. His run in the car was after I raised the needles a bit to see if that made any difference. The car wouldn't rev above 4k for him even right out of the pits after it idled for a bit. I should get more feedback from the other two who drove the car prior to me adjusting the needles. I did not check the bowls on Sunday, so I guess it's possible there could be some debris in the valves, but there never has been anything there in the past. We run a filter near the tank and another before the mechanical pump. Both filters are 3/4 full of fuel when we check them in the pits, but I don't know what they look like on the track at speed.

Thanks Bruce, I'll call you after work today before you leave.

Thanks for the help Captain! Yeah, I thought I'd get lots of responses too, but I guess I just didn't catch the expert's attention. Maybe next time I'll ask what the biggest tires I can run or if anybody has ever tried a turbo on a Z. I have taken the carbs apart many times to check the inlet screens and float valves and they are always clear. Last night, I talked to a British car mechanic and he too thinks it's a problem getting fuel to the carbs, not the tuning or carbs themselves. He suggested ditching the mechanical pump and the return line and installing an electric pump and pressure gauge. We already tried that, but maybe the electric pump we bought was a dud. Who knows... I also talked to a Z guy from Atlanta who races and he just went through exactly the same issue last weekend on his L28 powered 510. He solved the problem with an electric pump. He told me that the new metal bodied fuel pumps don't flow as much fuel as the old cast bodied pumps. I have never heard that, but I guess it could be true. SOMETHING is obviously wrong and it might just be that the pump can't keep up. He said one other thing that he said that made sense. I told him I tried to slide the needle up a bit to richen the mixture and the car ran even worse, cutting out at 4k rather than 5k. He said that with a richer mixture, I'm draining the bowls even faster which is why it cut out sooner. I was thinking that it was too rich at that point, but his theory sounds plausible. I plan to bypass the mechanical pump and install a new electric pump and gauge as well as block off the return line. The British mechanic will take a look at the car as well and give the carbs an expert tune.

I am at my wit's end and need help on my 260Z race car. Ever since I got the car two years ago, I have had issues at high RPM and after trying lots of things, I'm pleading for help. Here's the engine background... L26 engine just rebuilt with new rings, valve job, and a mild cam Thermostat guts removed leaving only the ring and cage for a restriction Prior to rebuild a few weeks ago, it was 100% original 3 screw SU's with SM needles, floats set to spec and chokes working smoothly and carbs synchronized. N36 intake Previously used OE needles in carbs New mechanical fuel pump with 260Z electric pump removed Previously tried another new mechanical pump and an electric pump as well Stock exhaust manifold with a 2-1/4" straight pipe and a single glass pack up front Clean '75 fuel tank with new filters Previously ran a POR-15 lined '74 tank with new filters ZX distributor with E12-80 module. 10°BTDC at 800 RPM and 37° total advance at 2500 RPM Previously ran stock magnetic pickup distributor So, the car starts right up and idles like a champ. It free revs cleanly and runs well at low RPM. On the track (car is not street legal, so all testing done on road courses), the exhaust note goes totally flat at about 5000 RPM and the car won't rev any higher. It makes no power at that point. Sometimes, the RPM limit before it goes flat is much lower than 5k. It's slightly better at part throttle, high RPM that at WOT, but the problem is still there. It doesn't always happen though. Some days, it runs fine for a short or even extended length of time and other days, it runs poorly right off the trailer. It happens at all temperatures and weather conditions. In the past, we had some success pinching off the fuel return line, but yesterday that didn't help at all. I tried moving the needles up slightly to richen it up and the problem got worse. We ran out of time to try moving them the other way. In the past, we have tried running with no air filter, we also tried running it with the hood off. We have the fuel rail thermal wrapped and we have extra heat shielding between the intake and exhaust manifolds. Nothing helps at all. The issue is exactly the same pre and post engine rebuild, pre and post fuel tank swap, pre and post distributor swap, pre and post fuel pump swap, and pre and post stock to SM needle swap. We have a 25+ hour endurance race in 12 days and we are out of ideas. Does anybody have a clue what's going on? EDIT: One thing I just thought of is that the temp gauge doesn't work (reads ~130°) even though I have swapped in another used sensor and tried a different gauge. The engine and radiator get hot to the touch like they should, but is there any chance it's running too cold?

Best of luck selling the car Arne. I hate to see you sell it, but if that is your wish, I hope there is a buyer out there that will pay you what it's worth.

Not tool design related, but has anybody tried an impact on the nut to get the pin started? I know that the rod will quickly get in the way once the pin is partially out, but I'm wondering if the impact action would help it slide easier.

I hear you Captain Obvious! My '78 was stuck so bad that a pneumatic-hydraulic commercial grade shop press was maxed out just to get the center portions out of the knuckles (and my car is 99.9% rust free!). I know that there will be some pins that cannot be removed with any puller, but like C-clamps or coil spring compressors, regular threads are not the thing to use. Acme threads work far better with less wear and better power transmission.

Will do Steve. So far, it sounds like there is some room for improvement in the available pullers. If that's the case, I will likely go forward with my idea. I just need to get as much feedback as possible so I can fix all of the weaknesses in the design.

What size all-thread was your tool? The one my friend bought only has about a 5/8" all-thread. The wall is pretty thin where it is tapped for the M12x1.25. I was thinking 3/4", but it could be even larger.

Thanks Leon. Do you think an acme thread and bearing would improve the tool, or not?

Thanks for the input Jim. I will experiment with the design to maximize the connection strength.

Thanks Stephen. I am thrashing to get my 260 ready for a 25:25:25 (25 hours, 25 minutes and 25 seconds) race right now, so I will probably order the supplies I need for the tools in mid-October if I decide to go forward with that design.

For those who have used a spindle pin removal tool, I have a few questions. First, did the tool work, and if so, how hard was it to get the pin out? Please give tool details as well. What worked well, and what could be improved? Did the tool have a bearing, greased washers, or ??? The reason I ask is that I'm about to make my own removal tool, but I want to build a better mouse trap, so to speak. Rather than using hardware store all-thread, I was considering buying acme thread rod to make the tool. I figure that 3/4" - 6 acme rod will make the tool much more efficient than standard threaded rod. A friend just loaned me a tool he bought online and it worked for him, but he said it was a real pain and the rod twisted under load. With a nice fat acme thread and a thrust bearing, the tool *should* be better and make pin removal a breeze. I have only done the pin removal the hard way. After heating and beating, I cut the pins off and used a huge shop press to extract the center of the pins from the knuckles. It was a horrible job and rather dangerous. That was all long before anybody came up with the puller tool and I haven't had to remove any since, until now. I have two sets that I need to remove and I want to make it as easy as possible on myself. I like good quality tools that work well and last forever. I will try the tool I borrowed to do one set, but I am not impressed with the design and want to improve it for the future. So, does the tool NEED to be better, or am I wasting my time? I figure that if I buy 6 feet of acme rod, acme nuts and some pipe, and I can make at least 5 tools and sell them to pay for my materials. The acme thread rod isn't cheap, but at about $25 per tool, I could make it work. I can get the standard threaded rod for only a few bucks, but if acme is the way to go, I want to do it right. If I do decide to go this route, is there any interest in a ~ $25 removal tool?

Sure Zed Head. I run an unmilled, unmodified (see note below) N47 head, a stock cam, a Nissan head gasket, ITM flat top pistons, and a stock EFI system. The timing is set to 10 degrees BTDC. I have run all brands of 93 octane gas - all with 10% ethanol and driven in temps from 40F to 95F. I did not check the actual CR, but from my own calculations, I get 9.82:1 CR. This will vary a tiny bit based on head gasket brand, but with everything else stock, it will come in just under 10:1. Here in the Michigan and Ohio area, we have 87, 91, and 93 octane. I have also seen 89 and 94, but like I said, I have only tried 93. The only engine mods I have are a AZC 6 into 1 header, a turbo oil pump, new flow-matched injectors and a potentiometer on the coolant circuit to adjust A/F. My plugs burn a perfect light tan color and I get 23 - 25 mpg regularly. I have checked my odometer for 100 miles against the Ohio Turnpike mile markers and it was within a few tenths of a mile TOTAL. The speedo is way off, but the odo is dead accurate with my 225/50R16 tires. Countless people have been running this engine combo successfully for decades. The main problem with detonation is that nobody bothers to check their head thickness before they go with flat tops. They assume that their 30 - 40 year old head has never been machined, but it's very common for shops to take a cut while the head is being worked on. Note: My N47 head is bone stock, and now only has about 15,000 miles on it. When I bought the head, it was brand new and had been sitting on a shelf since it was removed from a new engine back in 1977. It was owned by a race team and the head was never used. I only replaced the valve seals, but all else was in factory new condition.

The N47/flat top combo is only a problem if the head or block have been milled. I run that combo on 93 octane and have never had any detonation issues at all. I haven't tried 91 octane, so I don't know where the threshold is, but 93 works fine.

I figured out why cylinder #4 was dead on my 260Z crapcan racer. The intake valve seat is cracked and has chunks missing. The head went into the machine shop today and I'm awaiting word on what all is wrong with the head. Since this is a crapcan series, I can't simply throw money at it, so this will be a budget repair.