Tony D

I second and third the advice on the plugs, DITCH THE EXOTICS AND USE WHAT THE MANUFACTURER RECOMMENDS AND NOT WHAT THE PARTS COUNTER GUY GETS A BOUNS FOR PUSHING! A .69 cent plug works the best in these things, the exotic fine-wire crap seems to foul out every time and have misfire problems. Bosch seems worse than most. Simple plain BPRX-ES seem to do just fine. NGK conventional, Bosch Conventional, Denso Conventional... Hell, Splitfire Autolites work fine, and better than most of the fine-wired crap expecially in turbo service. They mayber fine for a Porsche that was designed around them... but not for the L-Series! Also, turn off all enrichments. ALL enrichments. Let the car warm to operating no matter how many times you have to start it. Once it's warm, with a basic map it will run well enough to do all the tuning you need to do. Enrichments are the LAST step to fine tuning the engine's response. Have them on while you're tuning, and it will only screw you six ways from sunday.

The 260 has float bowls of considerably less volume than the 73's. Under hard acceleration the single pump will not keep them at proper fuel level. A 73's larger bowls will hold level better, but when shut off will cause more of a hot start issue due to the massive fuel they can percolate into the intake tract, and how long it takes to reprime them. A 74 will perc only so much, and will refill to operating level (for idle) much quicker, but will also suck down under WOT much faster due to the smaller bowl volume. Operation of the 73 and 74 systems is slightly different, they do not operate the same way.

Back a page ago, solution #3 which was stated 'wouldn't work' is EXACTLY THE BEST WAY TO RUN IT! I know there is no 'best' but in this case, there IS---the regulation of the fuel pressure regulator is a BACPRESSURE REGULATION SETUP. This will (if you install a fuel filter before the carbs like you should) keep fuel pressure as constant as possible even with a plugging fuel filter and if you are using an EFI pump, will run the pump at the lowest possible amperage, and keep fuel flowing like a madman as it's only pumping to 3.5psi. If the filter plugs, the pump then can compensate and up it's pressure through the operation of the backpressure regulator (which will see a lower pressure at the carburettors and close off to raise it!) On High-HP cars in japan, this is how they are all run. Up to a given HP. And that level is very low. I'm not even getting into running a surge tank and then feeding fuel from that, but in high-g corners with a stock tank it's a requirement. I have starved cars running stock SU's in hard lefthanders with less than 1/2 tank and two fat guys in the car... Running lean at speed and load is not something you want to do. If you are seriously considering a fuel system, then ditch the stock rail altogether and plumb it up with adequate sized lines, and if you are worried about heat on track events or even highway blasts up to 2 hours (one fuel tank duration) consider a cooling coil and 1 gallon cool-can. I made one for a vapor-locky 73 (with round tops, BTW) which took a 7# bag of ice. Made it out of a 1 gallon igloo cooler and some coils of copper tubing. This more than cooled the fuel going into the carbs for longer runs down I15 to Vegas, and cured the cars vapor lock issues coming off the highway into stop-n-go. A 7# bag of ice would turn to a gallon of 100-110F water on a 120F day in about two hours. This was with a return line, so yeah you were cooling the entire tank. Anybody who has done dyno tesing on less than 1/4 a tank and had problems keeping AFRs constant will appreciate this hint as well... Easy to make, cheap, and will keep the car cool on the track. It doesn't have to be in the engine bay, but for safety I'd not be putting it in the back where the spare tire went... IN SHORT: Any system that puts the regulator in between the fuel source and fuel demand point will suffer more fluctiations than one which regulates pressure at point of demand by backpressure requirements. An example from the petrochemical industry: API672 requires constant oil pressure to the bearings of high speed rotating equipment (duh, huh?). The specified method for this is to place the PRV at point of demand with relief back to sump. Any filter media between the pump and the point of use then, becomes irrelevant with a positive displacement pump of sufficient pressure capability to overcome filtration restriction. I have seen 8 bar oil pump pressure, a drop across filters of 5.3 bar, and SILL have the required 1.7 bar at point of oil injection to the bearings. Later API specs have placed a secondary relief on the outlet of the pump now, to limit it's output to the pressure rating of any piping carrying the oil to the filter, but the effect is the same---the fluid is deliverd to the point of use with NO fluctuation whatsoever, and the lowest electrical demand possible on the pumping motor. Even if you are using a 15psi pump like a Holley Red, this will allow for PLENTY of filtration blockage and still deliver your 3.5 psi. If you regulate off the pump...and the filter clogs... Eif you regulate after the filter and the return line opens... But, if you regulate AFTER the carbs in a backpressure retention scenario, the only eventuality which will cause low pressure is a broken fuel line to the front of the car, a plugged filter will have to have 11psi delta to affect fuel pressure to the carbs, and a broken return line will cause no issues except for the fire out back... Same thing for Fuel Systems.

Obviously my sarcasam was lost in my post. People can't see a lot of things. People couldn't see us picking up 40HP and 1000 rpms of useable horsepower running 45ITB's compared to 45mm webers. Really, what people do you know in the USA that run 50 Mikuinis or 55 DCOE Webers? They were on the streets back in 1985 in Japan. The class racing rules here in America limit development. The dominant paradigm then becomes what guys racing HERE do for the cars, and not what unfettered development produces. The development of horsepower in the USA stagnated in the late 70's due to this phenomenon. The turbo years with E-Motive were exciting, but then it all stopped as everybody racing moved on to the VG's. L Engines were in the 9's in the 80's in Japan. And the development continues. Just like guys running XO Class at Bonneville with Flathead Fords. Because you can't see it doesn't mean it can't be done. And if you think the rpm limit is only 1500 to 2000 above what most here in the USA run (that 7500 magical stroker limit the internets are all abuzz about everywhere) think again. My youtube video has us shifting at 9500. That doesn't mean that is where we have to shift. And it's not a terminal limit to our build's upper rpm range. "We have not yet experienced valve float" is all I'm going to say. If we had a higher lift cam, our powerband would be higher, as would our horsepower. But for a 10:1 CR engine, I think 105HP per liter is decent...down a bit on horsepower compared to our 2.8...but then again it had 14.75:1 CR. And it had more power on tap if we would have used a more agressive lift cam. There are people on the street running the lift we run. Oh trust me, there IS power to be had. And if you're building a full on drag engine----LOADS of power to be had. 150-200? Child's play with preparation. Child's play I say! But not if you live in the American Box. Expand that thought box like someone in the NHRA would, and think of how to apply it to L-Engines. This stuff really isn't rocket science, it's just not thought applicable because it's a big V8, and ours is a small 6... Specific things may not transfer, but theory in practice is universal in most cases!

Here we go again making terribly flawed comments about a design that is old is somhow inherently flawed because we all know something NEW is automatically better than something old. NOT TRUE. I have discussed this with JeffP regarding the possibility of sourcing rebuildable seal/bearing packets for the pumps, and then having LD impellers 5 axis machined out of Stainless Steel. This would give us a pump that is basically 'lifetime'. The cost would be astronomical, but the advantage of 5 axis cuts over raw cast has been proven that you can get more flow simply due to the smoother surface. In some cases, the limitation of the castings is such that you can flow more because five-axist cuts allow for a thinner blade than otherwise possible, giving more physical clearance for the pumped medium to flow. Other than metallurgical advancements (stainless steel) and more precise machining (five axis versus cast) you will see that water pumps today sold by OEM's are very similar to pumps sold 50 years ago. You will also notice commercial pumps sold today are very similar to what they were 100 years ago. This stuff is basic engineering. There are no tricks here, you have a VERY versatile pump which millions of yen of development time went into to give best performance under various conditions. If the boys at Electromotive were able to cool a 1000hp turbocharged monster using an unaltered LD28 pump----er.... just exactly where do you think it has shortcomings? Since I just gave a basic class to some operating engineers and roating equipment folks in Brunei this past Wednesday and Thursday, my brain was scratched back on the basics of impeller design. I tried to 'quote' the photos above, but unfortunately the 1mpbs (advertised) line here at the hotel is not cooperating. Basically lets look at the two pumps and their differences. The LD pump impeller is larger in overall diameter. The LD pump has a larger center opening (or 'eye'). In centrifugal pump design this points to basic delivery changes. The eye (or impeller) diameter dictates flow---the larger the center of the eye, the more flow the pump will produce. In turbo terms this is referred in some circles as your 'volume tips'---when you get a rub in these areas your capacity goes down though you still normally make natural surge point like the machine did before the rub. Seond, is the pressure tips---or outer diameter. The larger outer diameter dictates more pressure. A rub or clearance in this area will mean lower surge point (earlier cavitation, at a lower pressure inside the pump). The LD has both a larger eye, and larger outder diameter to the impeller. Meaning it has both more flow, and is capable of producing more pressure under identical conditions as the non-LD pump. The biggest contributor to any of this is CLEARANCES. If you don't have optimal clearance from the vanes to the pump volute, or casing, your capacites go all to hell. Clay up a pump and check your clearances and you will see they are WELL wide of optimal for best pressure production. They may work at lower pressures and higher volumes, but tightening them slightly (tricky to machine when it's all assembled, eh?) can make for boosted performacne. Build a pump dyno---take a 5HP engine, belt it up to a pump mounted to a front cover, and give yourself some pumping capacity from some old 200L drums. I think you will find the 5HP pump will be a little shy once you start spinning it up there, but by simple experimentation with clearances you will see visible flow characteristic changes and resulting increases in pump horsepower requirements. You are chasing a red herring here, you are going after parts without understanding how they all work together. The design is sound, how it is presented in a mass marketed package is what needs to be addressed. Again, Electramotive used stock Nissan Pumps, but they did not leave the blocks, heads, theromstat, etc alone. They optimized flow, and ran a belt driven pump. If it cooled their beast, it will cool yours. Custom impellers? Really with the flat performance curve you will find this impeller design has, you are oging to see it's not required. It's not a high tech design like a turbo impeller. It's a centrifugal pump. Talke a look a gorman rupp, worthington, flowserve, dresser rand, sunstrand, any of the big manufacturers out there. Get into their design engines and compare the impeller design sizes with what they have for commercial offerings. you aren't going to change the world using the stock front cover. You wanna sling a completely independent pump housing off one side of the engine, then you may accomplish something. But working with the stock stuff will be an exercise in futility until you start gaining a grasp of the interplay between the impeller and casing clearances at a minimum. Impeller design IMO was optimized long ago. It's just so many people look for a short-one-shot magic bullet solution rather than sweating the details of proper flow management of fluids through the engine they miss the answer that is there in front of them. The pump is not the problem, guys. It never was. What those bike kits are giving you is an impeller like what we ALREADY HAVE in the L-Engine to replace cheapo stamped sheetmetal pumps that OEMS like to put out there these days. It's apples and oranges. The bikes have a pump design that is not optimized, our engine does. Look at that impeller in the last link, and compare it to the photos of the LD and stock L engine impellers. Because a Chevy has a bad pump design doesn't mean a Chrysler does as well. Same goes for bikes and Datsuns. Pump clearances can be addressed first, without putting on an impeller that is investment cast (slightly smoother and more precise shaping)---the ultimate pump impeller will be a SS Five-Axis Milled design and you will pay accordingly. But what will you get for that cost? Not much if you don't FIRST address tip clearances. And once you do, ask yourself the question "with all this new pressure and capacity, do I really need to improve further?" At some point, this becomes a tossers game. Use your head more, and then TEST. Mental gymnastics only work if the mat you fall on isn't covered in broken glass...

For gawd's sake man! Check your tank for snakes! Black ones in particular. Theys be very pesky and cause all sort o'trouble when theys commence t'moanin'! Oh, and BTW: " I'm connected straight to the battery, and I still see 10.7V when it's making the low sound, so I don't think the voltage is the problem." I think voltage like that will burn up your pump quicker than you can say 'overamperave from undervoltage' --- these high draw items are designed to run on 13.8 vdc nominal, 14.2 optimal. You run it on 10.7vdc, and you're asking for lifetimes shorter than the gas company employee looking for leaks with a match! If it's not cabling related, figure out what is wrong that you only get 107V at your pump under load. That is FAR BELOW ACCEPTABLE!

MMMMM, Rover 44mm HIF equivalents, gaaaaarrrrrrgh!

Dont get hung on US Mandated emissions equipment. Which is the impetus behind the CHT repositioning to the rear of the head. It reaches tempoerature quicker, putting it on closed loop and enabling emissions components earlier. It has an added advantage of being slightly more accurate for severe duty use, but Eurospec cars had 20 more HP and their temperature sensor was in the lower thermostat housing just like any other Z... It works fine there, you don't need a CHT. Now that thermister idea, that might make my VW or Corvair swap a bit nicer since finding those sensors can be a bear. But for a Z it's boar-hog teats---the thermostat housing mounted sensors work fine. And did everywhere in the world. The US is different because of the emissions requirements at the time.

Valvetrain turning forces soak up far more horsepower than most people think. The advent of roller cams in domestic V8's isn't to allow more radical camshaft profiles, it's literally giving up 30HP to the wheels which is otherwise wasted internally by the very forces you witnessed! Imagine how much smoother that cam would turn if you had rolling friction instead of sliding friction...

I know people who run 0.575" lifts on the street, will those springs work? The opening part of the runner to the valve bowl seems 'necked down' more than usual. Hard to tell by the photos whether you are imparting a spin into the bowl, or just haven't opened them up equally on each side. What does the manifold port flow for the one you are using (have you checked flow with the manifold on the head, in other words, to see if you overdid your ports or have to work the manifold?) Knowing what the manifold does to the head flow numbers lets you make decisions on altering the runner tracts to get something flowing better or more equally.

It's old news in Japan... As they say "expand your mind...and your rpm peak" Apparently they haven't heard of the 7500 rpm limit on strokers due to that explodo-harmonic issue. Must only happen on export-bound engines...

free engines you say...

crap, my GPS is up in the room. As I was riding the bus from Kawagoe to Narita last month, I was popping in marks on my GPS for the junkyard industrial areas on the main highway through Chiba. It's hard to see the JY's over the fences the way the road surface is sunken compared to the banks of the roadway. But in the top tier of a tourist bus, you see into the yards OVER the fences! It helps to use Google Earth, everyplace I noted, you could see on Google Earth later. Missing you by a week or two, heading back there in February... Outside Kuala Lumpur now...

I'm out of town till 2nd week of February, any interest in scanned versions of 1988 vintage phosot showing a TC24B1 Headed, 3.3L with three HKS Twin-Power CDI's and 50mm Mikuinis? I took several rides in it at the time... does that count?

Weber has no provision for cooling bodies, Mikuini, being an OEM fittment in hot climates, has them. Advantage Mikuini. I don't think a dead-headed fuel pressure feed scenario can properly be regulated without a Pulsewidth Modulated Variable Speed Fuel Pump---correct me if I'm wrong but somewhere in the system is a check valve, regardless of the e-cheaps dial a regulator installed. When the engine is shut off, fuel gets hot, expands, and sinks the floats off the inlet jet making for a high float bowl level (and possible hot restart issues). With a return line and proper bypass FPR, this can never happen if components are working. With a returnless fuel system, it happens every time the car is shut off. Backpressure regulation of the fuel rail to tripples is the most efficient and precise way to meter fuel equally to all carb inlets. With a restrictor style 'regulator' all you do is overwork your fuel pump and run the chance that the last carb in the line is the first to run lean (nice for #5/6 which run hottest anyway...) If you have Webers, you have to insulate against heat, there is no way to run a cooling body. Wayne Calder had Mikuinis on his 3.2, and would percolate like crazy in the summer heat in SoCal. The addition of cooling bodies made it like night and day, afterwards the car ran in hot stop and go traffic like an EFI vehicle. No more stumbles, gas smell, bucking surging, etc... If it gets hot, Mikuinis are the only way to go, if you're stuck on carbs. Most of the area north of AZ,NM, and SoCal have enough aerosols in the atmosphere to really cut the UV radiation to the tarmac, and consequently the air going through the radiator and into the engine bay is likely very close to ambient. In the perviously mentioned states, on an 85 degree F day, the thermal layer into the engine bay, BEFORE passing through the radiator is close to 130F. For all those who pooh-pooh a 160F thermostat, keep in mind that air coming off the radiator will likely be within +10F of your thermostat rating. Nothing I like more than blowing 200F air onto the carbs and components in the engine bay... It's a system, people put bliners on and look at one thing at a time, have the best components imaginable, and can't run worth a hill of beans when it gets hot because they didn't look at the package as a whole.

In short, Daeron made the same mistake 1FastZ did when making the statement 'the cap gives you pressure in the system, the pump only makes flow'... As Oz mentioned, there is 10posi in the block at idle BEFORE any blanket pressure adds to the NPSH at the inlet to the pump. The pump imparts flow, to be sure, but the flow against the RESTRICTION of the thermostat or orifice or block internals causes that flow to diffuse into PRESSURE. Block pressure will be close to 40+ psi at speed. This is cold. Blanket pressure will add to this directly. It is THIS pressure that combats the spot boilling phenomenon. Our heads are particularly prone to this in some way, as even with STOCK engines it's not unheard of to get runaway overheating in SoCal on even moderately temperate days with only a bad radiator pressure cap. There is a reason Electromotive ran 3 bar + blanket in their big horsepower car, it fought that phenomenon quite effectively. The pump will add even more pressure to that. It's the differentiation between static pressure (the cap) and dynamic pressure (that imparted by the flow of the pump meeting restrictions. Understand Electromotive increased the flow capability of the engine some 300%, and ran a 3 bar pressure cap. It's like the discussion on boost. Sure, you can boost to stratospheric levels and make 300hp at 15psi. Or you can port your head and increase flow to get 300hp at 8psi. If you have adequate blanket, and a properly flowing block and head, the electric pump may be all you need. But short of that static blanket, you will need the mechanical pump to force the flow and MAKE dynamic pressure where it's needed (in the block and head) to combat spot boiling and the results shortly thereafter. The 'hole' you are thinking of is the addition of blanket pressure. Go look at some high dollar people running electric pumps in CONSTANT SERVICE (roadracing, not drags or short sprints) and you will find very high pressure radiator caps on their cars. They have the flow, and in this case the cap pressure is their insurance against spot boiling. If you run a standard cap, likely there is the possibility that you can run into problems with the lower flow of the electric pumps. Wasn't GM using an electric pump on one of their V6's? If they have optimized the cores for flow, and were attentive to casting surface finish, this may be possible to do---when the OEM's start doing it, the technology has come of age for durability and warranty consideration. Till then, it's limited usage on lower output mills.

NASA has just announced the cutting of the price for the surplus Shuttles after they decommission the fleet soon. Due to maintenance required, they are dropping the price of the shuttle (some assembly required) from $42mil to $28mil. Anybody who knows me, knows I'm a sucker for a fixer-upper, and at this price it's almost too good to let pass by. Besides, it will really P.O. Branson if I get one and he can't have it! Whaddya guys think, sell off the shark car and go for H2 Green-Burning Rocket Power? You think I can swap a Chevy in there to cut fuel costs?

HIF 6's, gaaaarrrrgggghhhh!

What, yours doesn't go 160+? Mine does 173.325mph, and I shift at 9500...

"A hybrid of the two is just a CF IMO. With all the effort need to install an EFI pump, surge tank, larger return line, etc. etc. to run EFI, you might as well just go all out EFI. Or stick with carbs." Totally agree! Hell, strip out the venturis, turn the carbs into ITB's---that's the plan for my crate of 40PHH's out in the shed anyway. Screw some injector bungs from MSD in there, and run a 12X12 megasquirt. Carbs...er... 'blow'!

Is the rubber portion of the dipstick in the right place. Over the years, they can get loose, especially if the owner is really brutal in pushing the dipstick back in for some repressed phallic reason. In these instances, the rubber seal stopper on the stick moves, and you can have the wrong 'false high' reading on the dipstick. Compare it to another one. I'm 8500 miles from mine or I'd give you a tip-to-sealing shoulder dimension. Someone with access to their dipstick can measure it. Just hold your dipstick in your hand and whip out the measuring tape. We can compare dipstick measurements later, when I return...

Dune Buggy dot com is usually a good site, that the totally neglected the modulator ring as the primary enrichment device for blowthrough carbs is amazing to me. Basically an orifice plate roughly equivalent to the diameter of your main venturi. Under N/A and low boost situations, you get no enrichment. As flow increases, the vented pressurized air to the flow bowl increases at a marginally faster rate than that in the main venturi, causing the fuel level to rise and the main circuit to go rich, in porportion to the ammount of differenital. Very effective. You go 'rich overboost' which is the safe way to go. I guess 'TimSystems' wants to sell his controller more than providing full disclosure on the subject he's talking about. Such is life when you sell things for a living I guess: "My way is better, since I sell it!" Sad. If you think this setup is 'uncommon' in a Z, you just aren't looking in the right places, and are probably 24 years too late to see them all over like they were in the 80's in the JDM...

Not at a power level consistently to tax the system to require them if all is up to snuff... but if he starts making 5 minute full boost blasts in 5th gear down the interstate... "I realy like my turbo setup but it eats fuel on boost." My personal best with triple blowthroughs was 4.5mpg....daily driving it in commuter duty I was getting 17.5, which was better than the worn-out SU's I had on there to get it to pass smog! "XNKE I measured that cam while at Delta cams with my dial indicator. It does measure .480 lift." If you saw 0.480" lift on the cam, that equates to a 0.720" lift on the valve. Normally gross lift on an L Cam is limited to below 0.434" to fit through the cam towers. If you meant valve lift, that is a normal enough number. If the ramps are assymetric you can have a steep ramp on one side. If you have a symmetric cam, the ramps and total time at lift is far less. L's like assymetric cams.

BINGO! NEW Lug Nuts new are under a $ at AZ, for the time taken to do this, and the cost of the inserts...you would be well ahead to just buy new. Not to mention the insanity of using a helicoil on a NUT. I mean, deep open-ended hex titanium or aluminum racing lugnuts, sure you want a strong thread of stainless steel and not AL or TI for the repetitions you will put on them changing tires. But on stock lug nuts?

I'd consider the Apache before the ZX. Mainly because of the price. Maybe Frank 280ZX...