ozconnection

Good to hear that there are some people who don't mind playing with a Holley. Theoretically, you shouldn't feel the secondaries kick in. But some people like the feeling but it means that either the primary jetting is too rich/lean and the secondaries are too rich lean as well as the secondary spring is too light. There is a momentary bog followed by a surge of power as the fuel flow in the secondaries catches up with the airflow through that side of the carb. On another point, you would be really surprised by how far open the primaries have to be tied with how many revs are on board before the mains take over from the transition slots! In my auto trans L28 with a 2.5K high stall converter fitted, I tune in drive. I jam on the handbrake, put the drive into '2nd' so its actually second and not first gear (good old Jatco box) and chock every wheel with a big housebrick, I have my own dyno to the stall speed! Since most cruising is done at or below this rpm, I can tune the carb on the spot under load at home! Really really dangerous....sure.....but I'm ready to pull the coil HT lead and only stand to the side of the car, never in front of it!! You could do this against a tree or something too but I don't have one at my place. Brick wall might be ok too. I'd still use the handbrake and 4 wheel chocks. I must also add, I do this by screwing in the idle speed screw, not winging the throttle by hand. I have my timing light attached with the tach feature on so I can see the revs rise as I tune the transition screws on the primaries. I also have an Innovate Wide Band O2 sensor telling me my mixtures. When you look down the primary barrels at the point of mains activation, fuel gushes out of the carb in spurts, hardly what you'd call 'nice atomisation' at all. Still, my car doesn't surge on the street as you'd expect it to with this happening. I guess the transition slot fuel feed is still dominant at that point and as more main fuel comes into it, there is a tapering off of the transition mixtures. Ya gotta tune your car in drive or with as many accessories on as possible, (A/C on, lights on) so there is a representative situation you will find at some point on the street. Tuning the idle without them on means that the car will not have the correct AFR when they are used and the thing may tend to die or run roughly or inconsistantly after a minute or so at the lights. The accelerator pump is where the work is needed. The setup procedure Holley use suggests there is some gap between the spring loaded nut/bolt thing and the diaphragm pivot arm when at WOT. This setup will use the whole pump capacity and is too much fuel delivery for the little L series. I actually do what Holley don't want too and unwind the bolt so that the diaphragm arm is preloaded and the arms movement pushes the diaphragm up to about halfway of its total movement. (You can put a flat metal washer or two under the spring to restore some tension to the spring so that the acc. shot doesn't become laggy.) The accel pump shot volume is reduced because you're using only half its capacity approximately. You'll notice the change off the line especially when you floor it as there won't be the massive dumping of accelerator fuel into the engine (which takes time for the engine to clean up) before the car starts to accelerate properly. You'll need to play around with this one, it can take some time to get right, but it's time well spent IMHO. Intake manifold design will affect all this. The Clifford is very different to the Arizona in this respect and I've mentioned this in other posts on the subject. You cannot grab a carb tuned on a Clifford and put it on an Arizona and expect all to be sweet as it won't be. I have two distinct Tune calibrations that I use (and recorded) whenever I decide I need/want to do some manifold swapping for R and D or tuning etc. I like having two separate carbs for this really. The Arizona suffers from massive induction pulsing and so reversion of the AF mixture happens strongly as the engine revs rise and the jetting has to be dropped heaps or a filthy rich mixture will be given to the engine. This is with a stock cam. I'm sure many aren't aware of this and why few make good power because they're running about 10.5 to one mixtures at WOT. "Holleeezzz don't give good power mate" Yeah right. Float levels are critical and largely decide how responsive your fuel delivery will be. BUT the levels change every time you pull apart the carb for a jet change etc so what I have done is using a sharp scribe, mark a horizontal line across the main body, metering block and fuel bowl on both sides for the mains and secondaries. Every re-assembly I do I can ensure that the carb goes back together exactly the way it came apart and this saves heaps of time having to worry about float levels. Yes I do check them, but only sometimes not everytime! :bulb: The other issue that's really dumb with a Holley is the power valve channel restriction (PVCR) is not easily adjustable. Problem is it's too friggin big. I'm currently using some fine fuse wire to reduce the size of the hole on both sides and that works. Some aftermarket metering blocks have this feature and use air bleed jets in them. Using a drill shank from a small drill set, you can see how big the original PVCR is so that can give you a starting point for how much smaller you may need it to be. Two stage Power valves are often cited as crap and there is little info on them. I find that they are progressive in their delivery rather than the 'all or nothing' standard power valves. If you must use a standard valve, I use a very late opening one, about 3.5 inches. My car idles at 17 inches in gear when warm so you can see the 'rule of thumb' Holley suggest just overfuels our little engines if it were to open at 8.5 or 9.5 inches!! The two stage opens a bit at 12 inches and the rest at about 5.5 so its acceptabe with a slightly leaner jet on the mains. That's enough. My brain hurts now.

That's true, people give up too early. The biggest stumbling block is the accelerator pump. The squirters and coloured cam are there for delivery adjustment, but people still don't realize that the total VOLUME of fuel delivered for our little engines is too much. You can easily drown the engine by just blipping the throttle, to the point where it actually stalls. I've done it. As you've stated, its a carb that's used on a wide variety of engines. That's why the pump is so big and without tuning this properly, people just say...."Them too big those Holeezzz" Easy trap and most of the write ups often fail to address this situation properly, if at all. I know how to do it, simple really but someone needs to start a new thread for this kind of discussion! :bulb: The size of the primaries, both the venturi and the throttle plate are not too large at all for our engines (List 7002 390 cfm 4 barrel) and the secondaries are progressive (Vacuum operated) so that's appropriate in terms of airflow. The 390 is an excellent carb IMO if done right!

I'm not trying to be an arse here but c'mon boys this wasn't a hard question at all.......... but it seems to have tripped a few of the veteran posters up. Answering engine questions from non engine builders does this, it seems. LOL So to put this one to bed, all L engines have the same front cover except the taller LD28 and L20B engines.

I ran with SU's for a few years and a few things come to mind: the mid range torque and the sound of those carbs. I don't know how hard it is to tune DGV's but with a mechanical secondary on each carb, I'd like to hear them at WOT! And yes, the Holley gets whipped again What's new?

Hmmm, I've heard of this. Seems to be common on the Z but I'm not sure why.

Argniest, you're a funny guy!:classic: You're welcome. Cheers.

Yeah mate, the 27mm or 1 1/16th measurements refer to the bolt head diameter. The 16mm reference is how thick the bilt shank is. The pitch is how coarse the thread is, usually expressed as how many turns per mm. 1.5 mm is a coarse metric thread. 1.25 is fine and 1 is very fine. Google it mate...seems you have access to a computer! :stupid: So in bolt speak you have a crank pulley bolt "M16X1.5" (M is for metric). Head sizes can vary. Take a look at the camshaft bolt!! Same M16X1.5 as the crankshaft bolt in all other respects except the head.

That thing looks like the idle speed 'increaser' for when the A/C is turned on.

What worries me is that you've got no hot air coming out of your heater vents when the fan is on. They're hooked up and the hoses aren't blocked up with corrosion or kinked or anything? Other than that, it suggests to me that your thermostat isn't working correctly. Let's look at what a thermostat does. Understanding its job will help you assess the situation more thoroughly. At start up with a cold engine, the thermostat is closed. The engine runs and the coolant gets hotter as it absorbs the heat. Depending on which model you have, some water is allowed to circulate via the internal bypass passage in the block. Some engines also have a small hose that runs from the thermostat housing to the water pump inlet side, the external bypass passage. Now, as the engine coolant temperature reaches the thermostat temp. setting, the thermostat opens and allows coolant to flow through the radiator, to cool things down but as the coolant renters the engine head and block it mixes with hotter water and the overall temp drops a little. When it gets back to the thermostat, if too cool, the thermostat will close a little to reduce flow out of the engine and into the radiator. This will have the effect of raising or stabilizing the coolant temperature to a point close to the thermostat temp setting. Make sense? Your thermostat, if stuck wide open all the time, will allow too much coolant to be cooled...thus your condition as you describe it. At idle with the car not moving, the coolant guage will come up to halfway.....yes, that fits in as well. Don't forget that the heater is a mini radiator too, so it will make matters worse by cooling things down even more. (You can use this fact as an emergency "extra" cooler in the summer months if things are getting too hot...I did when I was towing a really heavy load a few years back in the middle of summer....an engine saver. I just wound down the windows a bit more to cool the cabin down a bit!) Get a warm(ish) thermostat ie 180 degree (hell even 190 for the cold months, swap it over when the warmer months arrive), your engine will run more crisply with the oil temperature closer to optimum as well, Cold oil robs power and doesn't work as well when cold. The cold outside air will be dense and that will keep your engine running strong. Cold engines wear more quickly so get things sorted man....change that thermostat, sort the leak and let us know how you go. Cheers from OZ!

Ok, wheel spacers may not be the solution for everyone, but they do exist for the very reason you need them...to move a scrubbing tyre off what its scrubbing! To install....take your wheel off the car, put the spacer on the wheel lugs and put your wheel back on. That's it. If ya "just gotta have these wheels and tyres on the car", this is your most simple solution. Good luck mate.

Get some 5mm aluminium wheel spacers from your local parts store or look 'em up online...ebay perhaps.

Wow, that's some response!!! I appreciate that you're learning your way around your car at the moment and unfortunately you seem to have a lot on your plate with that machine. I guess the best place to start...is over. I know you have mentioned that a mechanic has looked over your car and has given you the thumbs up. That's fine, but have you done the checks yourself? When you do, you'll learn more about your car everytime. A check by the mechanic doesn't teach you anything. Mechanics, like doctors, get it wrong sometimes. Looking at a part and assuming they're right (like your leads) is wrong. Test them. All sorts of electrical mayhem can occur because you've got one faulty ignition lead. Learn how to test them. Google it if you have to. Your FSM might also give you the values you need. YOU need to establish and continue a systematic checking procedure of all your systems. Get an exercise book and index it. Write dates down when parts are replaced. Take notes and even photograph it. Eventually, you'll build up such a vivid mental picture of the workings of your car, you'll be able to do anything just thinking about it. Experienced Z guys and girls will know what I'm talking about here. Don't skimp. Don't assume. You'll never get it right if it's wrong and you thought it was right all along. Beg borrow or steal the tools you need to get the job done. Join a local car club and pick the brains of locals who may have experienced similar difficulties. Borrow their tools. Post questions on forums. I don't own a Z and my car isn't injected so I can't give you specifics about your car. Someone else might like to chime in here in that regard. Cheers and good luck mate.

You have to understand that all engines are built differently and as a consequence, have different dietry needs. To give you 'random' figures as to what will right as opposed to what isn't is risky at best. If I said wide open power AFR should be 13.2:1 and you ran that on a 15psi boosted turbo engine with cast pistons, you'll be looking for me in a real hurry.... Firstly, you need to give us a detailed account of your engine. What mods? How does the car feel in its current tune? Are you looking for max power or best economy? Ok, on my L28 with stock cam and head, stock compression auto trans, 800 rpm idle, Holley 4 barrel, Arizona 4 barrel dual plane manifold, headers and a 2.5 inch exhaust, MSD 6 and a 280 zx dizzy running 22 static and 34 total without vac advance, I run: 12.8 at idle (to keep the idle strong when the revs drop on selecting drive, in fact I tune my idle in drive for this reason) and when I use the power steer and the A/C is on. Idle vac is 16 inches in gear, 18 in neutral and AFR falls to 11.9-12.2. Plugs have a nice light grey colour too. See what I mean!!!! Cruise is around 14.5 and WOT I like to see 12.8-13.2 I use Aussie premium unleaded with a octane rating of 98. No pinging is detected. I use a 180 degree thermostat, water wetter, distilled water an LD28 water pump and a 20 psi radiator cap. All this to make sure no pinging...at all. A large electric thermo fan keeps temps in check. Do some driving around if you can. Adjust things, get out there and feel what its like to drive. Look at your innovate and get a feel for what 14.5 is like for example. Adjust a bit leaner and how does it run? Does it surge or hesitate? Soon you'll get a feel and you'll know when its feeling strong. Depends on how anal you are to get it right. I spent heaps of time on it and was able to get things to the point where I was rejetting etc for the seasons! To me, that's where I wanted to be..as good as or better than a factory calibrated car. It can be done. Good luck mate

These guys sell complete spray bar assemblies. http://www.mjpshop.co.uk/product_info.php?id=81&pid=255 There might be someone more local though, keep trying. Cheers

Dave, do you worry that the weight of the fans will damage the cooling fins eventually? Maybe the aluminium is stronger than the factory style brass fins because when I did the same on one of my stock radiators, the holes became quite large and the fan jigged around only making things worse. :disappoin What do you think? I stayed with thermo fans because they worked really well like you and others have found. I eventually used aluminium strips with small rubber strips between the aluminium and the radiator to support the fans and prevent chaffing on the core. I also used the factory shroud to help cooling even because I have a tranny cooler and an A/C condenser sitting in front of the radiator. A shroud is an option if you don't run with these 'add ons'

Brian, Nissan engineered a single carb arrangement for their passenger cars. Cedrics, Laurels, Kenmary's and Skylines all had them, if not for their domestic market, then for their export ones. A single carb, in standard configuration doesn't make huge amounts of power and less than a standard twin carb setup. Modified, however, substancial increases in both power and torque can be had from using a larger cfm carb, either from a big two barrel or small 4 barrel carb. I have run a single Holley carb for years. Two barrel 350cfm then a 4 barrel all the way to a 650 spreadbore vac secondary. On my cruiser, a 465 4 barrel is on there atm, and runs great!! I really like a small 4 barrel the best, each barrel is small and gas velocity through the carb is kept high for superior fuel atomisation. When all 4 barrels crack open, there is enough cfm to satisfy the engine. There are obviously factory Nissan manifolds available that a two barrel and even a 4 barrel with adapter plates will work with. The Clifford 6=8 manifold has a massive plenum under the carb base that slows the air velocity down heaps and throttle response suffers. For maximum power, the Clifford is king, however. Its a dedicated 4 barrel manifold as is the Arizona manifold. Entirely different in design, the AZ mani is built for low to mid range torque which suits my application perfectly...ie street cruiser. The differences with the stock manifolds is mostly to do with runner length and internal diameters. This will move the power and torque curves around a bit but nothing gigantic. Most of the poor reputation is because some guys don't take the time or have the patience to set these up properly. True, I spent quite a bit of time sorting mine as there is no FSM that tells me how to set it up unlike the twin carb factory setups. Fuel economy is very good and it starts hot or cold, summer or winter very well, has an electric choke and the hot water stove in the manifold is NOT connected. This manifold is poor in this regard, unlike the Clifford which has a huge stove at the bottom. On the coldest winter mornings, it may take longer to warm up but not like 5 minutes, maybe a 1-2 min. warm up, that's all. Check out youtube. My 280C (DAT28C) is there, with lots of performance vids all with a single carb. for you to watch. Good luck with your project

More power than an L28et? Some guys are getting 400 rwhp and as many torques from these 'old' engines......and you want more power than that?

There has been some very solid advice given to you already, well done people. Your job now is to read....read....and read. Understanding what you're trying to achieve is critical to the correct order of operation. Spending some money now on a tune up OF WHAT YOU ALREADY HAVE is a fantastic way of learning how everything works together. Modifying a car can be/is a rewarding exercise but to do it now without actually optimising what is already in front of you is a mistake IMO. If the car was in a very good tune already, I might suggest that you could try your hand at tinkering but your car needs some work and you need some experience. There you go, a good match already. Consider a medical officer. He wouldn't be able to necessarily perform the more complicated procedures without actually doing a stint as a general practioner first, gaining first hand knowledge and experience. As a Maths teacher I'm sure you'll understand this concept. There are those who'll disagree with me arguing that experience will only be gained by modification. Most of those people probably live at Hybridz. When it comes time to modifying your ride, you should take a look over there as well. However, be warned, if it appears that you haven't done your homework and researched the topic and ask a 'dumb' question, you'll be slammed. This site, IMO is much more tolerant of people asking 'noob' questions. At the end of the day, good luck. Get yourself a factory or aftermarket service manual and study that too. Give yourself small tasks and perform them as well as you can. That's how you will become familiar with your car and the world of mechanics. All the best mate.

That makes perfect sense to me, but I don't think anyone else will know exactly what you mean. Could you rephrase that please?

I have driven an R31 Skyline with the RB30 engine in it. Smooth, torquey and quite fuel efficient is how I would describe it. That's how I would describe a well sorted L28 as well. I really don't see much of an advantage by running an RB30.....once the bonnet was closed nobody could really notice much of a difference. But if you really must gotta have one....... Good luck mate.

Excellent advice here....take heed my friend. I don't think ANY stock L Series puts 135HP (100kw) to the wheels, flywheel yes but not the wheels. Sooooo atw maybe 100hp or so. Good luck with your project.

A word of advice mate, you cannot possibly expect a solid answer to this question. Let me give you an example; "Doctor, my stomach aches and can you tell me why?" He'll be able to answer you after a bazillion questions but it will take some more effort from you to help him help you. We really would like to help you with your question but you really need to give us a lot more information such as: What car/engine is it? Have you worked on the engine or is it standard? Does it do/doesn't do this all the time? Have you had your car assessed by a professional or at least seen by someone who knows our cars and given you some tips? Fresh fuel? Solid spark and timing? and on and on it goes.....your turn mate.....info please. Good luck.

:bulb: If you're worried, make your own.

Does the crank turn? Measure how deep the cylinder is with the piston at the bottom of the bore Kangaroo steaks for everyone!!!!

Fantastic effort Well done Guy!