brokebolt

Ever Z I have crawled under has his hunk of metal in different configurations though. I agree that is a factory item, my 1973 had it even though the other site listed here said it was an upgrade in 1974. It made a great exhaust hanger when I was making custom pipe. Also great for a rub rail on lowered cars. I couldn't tell a clunk from a clump in my old heap, she is a bit of a rattle trap!

Piece of cake! Place the rubber seal on the windshield glass and make sure it is nicely seated in the bottom of the channel of the rubber all the way around the glass. Now go down to the hardware store and get a nice fat (3/8" or so), soft cotton (or other soft to the touch) rope and than grab a spray can of white grease. Spray the white grease in the channel of the rubber gasket for the window frame, lay the rope all the way around the rubber channel over the grease so that the ends are at the bottom of the glass. Spray a bit more over the top of the rope. Now place the glass on the cars window frame and gently pull the rope both right and left at the same time not getting ahead on either side. This may take a few tries to get it right but it should work. If it doesn't seem to be going in smoothly stop and restart. You don't want to bind the window too much or it will break. You may even want to add a little white grease to the window frame before the rubber is placed over it. The white grease will help lubricate and pull the rubber into place and the rope will pull the rubber back and allow the edge to overlap the window frame lip. I have done this may times on many different cars (I used to work in an auto body and paint shop). Now go drink a beer and rejoice in your success. Cheers!

Your welcome!

The water flows from the front carb (radiator side) to the rear carb though a passage pipe that should be between the two manfiold halfs. Sometimes these pipes have been removed. Basically each manifold half has a hole threaded for, if memory serves me correctly, a 1/4" NPT barb hose fitting. The water inlet on the front manifold is feed from the thermostat housing throught the front manifold body and exits into the passage pipe (if still pressent). The rear manifold is feed from the passage pipe throught the rear manifold body and exits the rear (transmission side). This coolant will be returned to the other side of the motor to a 'T' fitting that is feed from the heater core return and both feed into the water pump pick up which has a large radiator hose connection and a 3/8" NPT threaded hole, again it memory serves me correct. The heater core is feed from the passenger side of the cylinder head in the rear (just a bit of info).Your car may not have this set up exactly as described as it is 30+ years old and people like to remove stuff, but that was how it came from the factory. Both sets of inducitons you have should have water passages in the manifold. The 1973 version also had one that fed the balance tube and additional water passages on the carb bodies, if memory serves me correct. While I'm at it, they used a funny thermostat that when hot cut off the water feed to the manifold, remove that junk and toss it. It gives you nothing but problems as they never really did work well...at least mine didn't. The dealer no longer sells them and actually suggest that I do this years ago when I was looking to replace mine, smog reasons. If the fuel rail is in good shape, great!!! I would disconnected the fuel rail from the car and use some compressed air and blow thourgh it to remove any bugs that may have made a home. The non-smog balance tube may be hard to locate singlely but check out E-Bay and this sites 'for sale' posts for some good used junk. Also Zcar.com has a 'for sale' section. You may want to post a advertisement in the 'parts wanted' section. Best of luck on the project.

I'll answer each inturn. 1. Use either one. I have heard that the 1973 version has larger internals and flows better, honestly I have inspected them both and see no difference. I used the 1972 cuase smog wasn't an issue. If you want to keep it *cough* smog legal use the stocker than came on the car. The 1973 version will have, or at least at one time, had all the smog stuff mounted to the balance tube. 2A. I think your talking about the balance tube? It links the two manifold halfs together on the top and uses two bolts on each manifold. The 1972 will have no EGR port and the 1973 will have an EGR and it is ported for such. It also has water jackets for faster cold start warm ups. Unless your worried about smog you can use either balance tube. 2B. Use what ever fuel rail you like. I have seen no major advantage between the different fuel rails. But make sure you use a return line, all the stockers should have them but being 30+ years old good luck finding something that is in original factory condition, they are usually all rusty and such as they were covered with a insolation wrap to prevent vapor lockup and a host of other problems. 3. The heat sheild should bolt up fine. The only difference between the variations of the heat shield is that they are cut for a heat riser tube that is used on some of the 1972 air cleaner intakes. Those air cleaners usually had a winter/summer selector. The 1973 used an intigrated version but still used the heat riser tube from the exhaust manifold. DO USE the heat sheild (weather stock or aftermarket or home made) as it will greatly reduce carb heat saturation, especially in stop and go driving or long idleing. Never used, Ztherapy so I can't comment on them but lots of others here have and they seem to have a good reputation. If the carbs you got work than, no worries! Happy motoring.

"on most others...big bore TB on a round manifold flange..." I wasn't really talking about the round TB and intake manifold from the L-6 cylinder Datsun. I was more speaking towards the 240SX swap that is popular for EFI guys on an aftermarket manifold, although I seen a Weber TB once. As I stated the stock manifold is oval or "egg-shaped" as you called it. While we are on it, I seen a round log style intake manifold that looked like it was made from round stock welded together with equal length runners. Looks like that could be a performer. Seen one with a TB between cylinders 3 and 4. That too might perform.

Plastic if not designed for solvents do get brittle. I would definetly make sure that the plastic was safe. You should be able to find a oil filter assemble from Mc Master Carr that would better suit the need. Look for a hydrolic assemble and that would work the same...

I stripped a car once long ago with this type of TB. If memory serves me correctly the manifold is also shaped to match the "oval" TB shape vs. the round version found on the round bore TB that is on most others. I did some "light research" and again if I recall the gains is much less than a big bore TB on a round manifold flange...

Personally the bang for buck is just too high. As stated you can get new carb set up for about that, cheaper for used stuff which if unbroken and in good working order will operate the same as new stuff (the bodies don't wear out just the wear parts). Also the troulbe to convert maybe too much trouble when you look at the easy of bolting on a set up designed for the L-series head. Moreover the Mikuni web site list the pilot jet really small like max of 35. Unsure if that would do it or not.

Hey I noticed that nobody mentioned that motorcycle carbs have two types (or I just didn't see it). Like the SU carb their is a slide bore carb (as I heard a bike guy call them) and a open bore carb (again his terminology not mine). I would think the open bore carb would be the better of the two types as the slide bore would be using engine vaccum to open the venture. I would think the vacum would be different between the two engines simply becuase the RPM range is different and the fuel requirements would be different. But if you figured out the fuel curve on either set up it should work. The bore size, if larger than like 32mm should be fine; what does the SU meassure??? 38 or something. After all the magic of the carb is the bore size vs. the ventrue size...the rest is just fuel metering. With a smaller bore carb you may not gain any performance advantage over a twin SU set up or 40mm triple carb set up but that picture posted here sure looks like a nice set up. And if your a bike guy you may have everthing you need to tune them which in multi carb world is a HUGE advantage; six bores means six sets of everthing; huge expense their. Kiwi303 I say try it and if it works...great!!! Just post your results for others to follow and sponge off all your hard work!

Mine didn't backfire when it was rich but did puke out blue smoke...and lots of it. No backfire on deceleration and none of acceleration, from either out the intake or exhaust manifold. Also had a motor where the timing chain jump a link due to worn/broken chain tensioner. Same issue but raw fuel that would burn the eyes, like a top fuel drag car warming up in the pits, just not as bad. A backfire can be produced by for many reasons both out the intake and exhaust manifolds. You would really need to determine the condition when it exist and work from there. Yes bad ignition can also produce a backfire condition. But like he stated it isn't doing it now, so... My main tip was check the easy stuff to confirm it is where it should be. Guage should cost about 20 bucks and a great addition to any tool box. They smoke when they are lean and they smoke when they are rich.

I am willing to bet that the electric fuel pump is overpressuring the needle and seats in the fuel bowl thus over flowing the fuel bowls. This is why the problem is the same on both sets of inducitons. Do a search here on solutions to this problem, fuel pressure or carb inlet pressure. I have responded to several posts so I know they exist. During testing mode, get a good quality fuel pressure guage and test the pressure first to confrim the potential problem and I bet your pushing greater than the required 5 P.S.I. Be advised that even with such a low pressure that with old or used needle and seats you can over flow the fuel bowls.

Remove the vaccum hose to the brake booster and plug the hole (do the same to all other vaccum taps). Do not drive the car in this condition it is just for analyst purposes. Start the car and check for the same problem. If the problem continues than varify the ignition timing to the crank. If the timing is good check the crank mark to the actual top dead center of the motor. Remove the valve cover and check the cam marks to the crank mark, and the top dead center on cylinder number one. If these three marks do not line up than you may have spun a harmonic dampener (very common) or your timing chain tensioner or slack guide is damaged/broken (also very common). A Chilton or Hayes manual will illistrate the location of the cam timing mark as well as how to determine the number one cylinder top dead center. If this all checks out than check the valve lash and cylinder compression numbers. It is possible their some issues with this area as they are adjustable and do need adjusting over time.

My best guess is you will have to make one. I do not know of any aftermarket product that fits the bill. I would suggest using a very thin sheet metal so you can easily bend it with your hand and also use a prick punch to put holes where you need them; better than trying to drill it, and quicker too. Once you got a basic shape and bends than you can make a permenant heat shield with a thicker material and aluminium too. My Webers have a bolt stud on the front of the carb so it makes mouting them quicker and easier on the air inlet side of the carb. I would mount it in the rear as a main mounting point and use some kind of support on the strut tower side...somewhere. Best of luck.

I ran a 3.1L with bell top SU's for years with stock needles and nozzles. It can be done very successfully. I prefer my engine with triples however. I also used a 600 Holley 4 barrel on a Clifford manifold. The Holley carb was a bit much for that engine. If you ever decide to switch your induciton there are many options to consider...EFI is also a good choice. I am not a big fan of the DGV but it is also out their. You didn't say what type of rods your using...stock L-24 or some aftermarket H-beam rod? Don't really understand the hood venting comment. If it is heat build up your commenting on, I would suggest a stock heat sheild on the induciton. I ran without one and it seems to keep the carbs cooler with one. I would highly suggest running one to prevent fuel bowl/carb. heating. My underhood temps were never bad but I did have to run a 280 Z radiator as the stock 240 Z unit was too small on hot days (90+) and in stop and go traffic too. I also used a 180 high flow thermostat. The 280 Z radiator was a direct drop in unit in my 1973 240 Z. Many a write up on aftermarket radiators here and other sites. Happy motoring.

My bell top SU's did the same thing, mainly on the rear carb. The fuel bowl would actually go dry (long story). I agree with what has been said, try one more thing to confirm your suspicions. Use a inferred tempature gun and get a reading off each carb top and then the bottom just after you stop then after the problem starts and just after it dies. Record these numbers so you know what the optimal temp is for your car. Now you can base line any mods and confirm that the mods are working. A good heat sheild is always a good idea. Buy a starter thermal blanket and bolt it to the bottom of the heat sheild for added protection. You'll have to cut off the velcro flap. Looks like hell but if done right nobody will see it without a mirror.

Square bore pattern on the Bob Sharp/Arizona Z car version. Clifford Research uses an adapter plate that mounts the square bore pattern to the manifold. The Clifford Research manifold has a large square hole without any carb mounting surface. If you use the Clifford Research manifold you can drill holes in the nitrous plate and mount it directly to the manifold...that's what I did. Makes it real low profile under the hood. I would gather that you "may" be able to drill a square bore to spread bore adapter plate (search Summit Racing SUM-G1401) to mount a spread bore carb, haven't looked at it close enough.

Tony D., Thanks for the info and the link. Great stuff. TimZ, Good call on the TB runner 'cut and paste' job that Monzter did. Monzter, Never too many pics. Great way to document your project...how many hours spend on machining/welding of the TB runners...or do you not want to add them up? On the plunum idea, I look toward the Pro Drag race guys for inspiration. By simply adding a half donut shape over the port that may produce a smoother transition into the throat of the TB, or I would think. Extruda body (advertised on this site) has a video on his my space page that demonstrates the effect and the half donut shape very well. It really is odd that something so simple in shape would generate that much more flow...but really I guess it is no more than a TWM air horn without the inlet tube. Post more pics as you finish more items in the project. This is definately a project I would like to closely follow. Might make a good multi-step article for Nissan Sport Z mag...

Sence you mention it, the plenum being at 90 degrees from the inlet to the individual runners, would that cause some blow over (not sure if that is a technical term)? But the question is as the air flows into the plenum would you have negative things happen to the air as it flows over the first, second, thrid intake runners and so on as it travels to the sixth runner. The original SU air cleaner put little side skirts on each side of the intake horns, I am assuming to prevent this...maybe it was just to hold the air cleaner in place? So with that said would their be any logical reason to experiemnt with an air horn that was round on the trailing edge and square on the leading edge? Just building off the ideas TimZ shared. The intake shown looks too long to me to be a Cannon and the intakes are curved, were as the Cannon I have is straight. Origiannly it looked to me that a stocker was cut up and the runners were re-organized as 1-4-5-2-3-6...than some fancy welding to make the standard side draft mounting surface either by cutting off the flanges on a stock Cannon (or other brand) or having some mounting surfaces fabed up as blanks like the headers were and welding them on. It is an interesting quiry. Either way it looks cool and original.

Hey Monzter that intake looks real good, almost like you cut up a stock intake...He, he. Their must be a lot of time spend on that project. Thanks for the pics. I noticed that the second injector ports 1 and 2 have the sleeves removed. Are they a weld in design? Again not a turbo guy but is their any gain to be had with a header style intake (like that posted) vs. a design like the stocker turbo Z had? Tony D., The "long rant" comment wasn't directed at you freind. I was simply trying to clarify on the original issue and not turn this into "if you want maximum output" discussion. Like it has been stated over and over, you can get more performance but at a cost (both $ and trade offs) and that was where I was headed here...or not trying to head. And yes being that turbo's use exhaust output on forced induction it is really a debate of cost, time, etc. vs. output. That system shown here looks farily costly and time consuming. For someone wanting max. output I would recommend to be prepaired to pay or spend time developing. I'm sure Monzter has done both. Personally I am not that concerned with max. output on a daily driver or hobby car...I would re'con most feel the same. I would gather they want the most perfromance to be had for least cost. If I were more sensitive I guess I would take offence to the "knuckle-dragging" comment. The spare tire comment was really a comparison that your gains would be about the same as removing the spare tire...or I would assume. Compairing weight to lost performance. I don't understand the ZC.C comment you might need to clarify that in a PM or something. Ya know, I thought this was a site of shared ideas...I even read the information posted by Superdan concerning the site rule and mission statement to make sure we were on the same page... So back to business, what is a 'bar and plate' I/C's you mention? I see the pics here posted by Monzter of the air to air cooler that I have seen in the past on other turbo systems and what not.

Long rants aside, and going back to the origianl quesiton; I guess what your really saying is that neither design is best. A radiused inlet like the example given from TWM would be the best or better than the two in question. So what plant in Fairfield, Jelly Belly or Bud? And what is a 'bar and plate' I/C's you mention?

I agree with what you have stated JohnC but do you think the two presented air horns you would have any real world difference between the two? In theory yes, and I agree that more turbulance=less perfromance. As far as I can tell this ideology hasn't filtered into other areas of turbo design, the stock turbo set up has some fairly sharpe twist and turns. I would gather that a air to air cooler would also be an area where you develop a lot of turbulance. Again not a turbo guy so I haven't followed up on any improvements sence like the 80's. My origianl comment I was speaking in general that if you not running at WOT you really should not see a "seat of the pants" difference in normal daily driving. I haven't followed MONZTER's build up or intended use for the engine so I was speaking more generally, not all out performance. Personally I wouldn't send the time to develop an air horn for the prospect of potential gain...unless you needed it for space limitations or something like that. Simply remove the spare tire and I think that would produce more performance gains over any air horn design. I could be wrong here but...

OK, I think we both agree that the conical shape would be best for any application but in forced induciton when you are producing more pressure than needed (a large pressure differential accross the throttle blade) would it make a difference in efficiency? How different is the pressure differential across the throttle blades in a turbo induction vs. a naturally asperated set up?

On forced induciton, I would gather that their would be no difference. After all you are building pressure in front of the throttle blade, that is at less than WOT. You should have less pressure behind the throttle blade than infront of it for most driving applications. I would also assume that the round shape would flow more evenly from any direction into the throte of the TB as aposed to the square one. I'm not Turbo guy for sure but it would seen logical to me.

A mini meet would be a good idea, but no Z from me I am a left coaster guy.