bjhines
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Posts posted by bjhines
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Ohh... and +4 offset makes the wheels sit closer to the centerline of the car...NOT OUTSIDE....I am sure that anyone running a ZERO offset wheel will have to cut, bash, or pry away even MORE OF THE FENDER LIP to fit 225/50/15s....
as mine sits...I have lowered the car 2"s and the tires fit without ruining the fender lips...just a neat roll up of the upper lip in the REAR ONLY...completely invisible from outside.
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Very Nice stick out of the Kumhos...I have video of my car with my camera mounted in Marks E-30...I passed him and then took it a little easier to keep him behind me the rest of the session....Mark was out turning me when I was running the Azenis tires...but I can easily out turn him with the Victoracers...
In fact the E-30 was constantly over rotating comming out of turns 2 and 4...I never fishtailed during the normal run groups...although i did get it a little out of sorts with trail braking during time trials in turn 5.
Rockingham ate most of the tread life of the new tires in one event. I am a little disappointed that they are going away soo quickly... I spoke with Rex about his experience at Rockingham in ITS a few weeks ago... He said he corded a set of Hoosiers on the front wheels during practice. He corded another set of fronts during the race...15 laps I think. I don't feel soo bad now...Apparently Marty corded a set of Hoosiers this weekend on his Miata too.
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A size that I use on one of my 240Zs with stock spring perches is....
15x7 +4 offset....225/50/15 Victoracers....less than 1/2" clearance to the stock spring perches.....I had to roll the wheel well lips to provide clearance.....fattest tire and wheel combo you can get in there without actually cutting the lips or converting to coilovers.
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A size that I use on one of my 240Zs with stock spring perches is....
15x7 +4 offset....225/50/15 Victoracers....less than 1/2" clearance to the stock spring perches.....I had to roll the wheel well lips to provide clearance.....fattest tire and wheel combo you can get in there without actually cutting the lips or converting to coilovers.
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I have a variety of wheels from stock Z car wheels, slotted 14x7" mags, to 4 sets of performance wheels in 15x7,15x7.5, 15x8, and 15x10.
They have back spacing that are anywhere from 4 1/8" all the way to 5 1/4".
The idea is to keep the center of the wheel the same location as stock...
Most people running 15x10" wheels are using 5"+ backspacing to keep the bearing loads correct. This backspacing will not only require coilovers...but it will also require very short spring perches in the rear to allow the tire to come as close as possible to the strut housing...within 1/2" to the actual TUBE...
Of course...all of this changes if you decide to mount brakes with thicker "hats" than the stock rear drum...as many willwood set ups do. The front disks mount to the rear of the hub so they do not interfere with offset.
I can also assure you that you will have to cut away the upper fender lips and bond on some flares to provide clearance to the outside edge of the tires....
Keep in mind that big slicks require extra camber, caster, and toe in rear ,and toe out in the front. These changes can end up moving the wheels forward in the wheel wells...so be sure you have all the parts set up when you cut the wheel well lips away.
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Hmmmm....check links on some of the Z web pages...I found plenty of distributor options for any year Z-car...I use a relatively good example of my original dist. with a pertronix module installed, hot coil, bypassed resistor, NGK plugs and wires, brass posted dist cap..I never have ignition problems...EVER!
I am not at all sure that the aftermarket dist. are worth the money..I am also very leery of their reliability and repairability.
Rebello may have some recurved factory dist. for sale...
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Motorsport Auto sells an adaptor to fit those carbys....
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For god's sake....Is that a bumble bee on the plate.....Tell me that was not in your filter housing!!!! Mud wasps are skinnier than that bug...but they are a real problem in North Carolina....They will plugg up any hole 1/2" or less with their mud nests...They only way I can store anything in my garage is by oil fogging and bagging every part.
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Timing can be tricky if you have changed harmonic balancers from a different year...Some were marked for scales mounted on the left side of the front cover...others were marked on the right. You can check TDC easily enough with a paperclip in the #1 spark plug hole..... just dont get it jammed against the cylinder wall. You can make a new TDC mark with a file or dremel tool. sometimes the keyways in the end of the crankshaft have been "rebuilt"....they are rarely perfect after such a rebuild.... a partially sheared crank Key...or a damaged balancer can also screw up the marks... I have seen balancers that "tore"...the outer weight could twist around...
The red stuff is bad...soo is the black stuff...You need to have the tank reconditioned...both colors of sludge will pass through fuel filters easily...right into the carbys....If you just can't wait to have the tank done...there is a drain plug...remove it and replace the copper gasket when you reassemble it....The upper vent lines are easy enough to replace....there is one odd sized section of hose that is very hard to find....there is also a line that passes through the right rear subframe into the rear Q-panel area(vapor tank line) ...use a soft string and a shop vac to pull the string through..attach hose to string and pull it through...
As far as fuel return lines go...You should set your system up to use the fuel return system...It maintains constant flow of cooler fuel in the system...the return branch and restrictor should be the last thing in line...after the furthest carby..the individual carby branches should be as short as possible...(less than 6")..to keep the supply of cool refreshed fuel as close to the inlets as possible. You should insulate all of your lines in the engine compartment...feed and return should have fireproof insulation...
You should have a heat shield mounted between the carbys and headers...a good heat shield design would also drain leaked fuel away from hot exhaust pipes....your brakes and clutch cylinders could use heat shielding as well.
the lack of a fuel return system and heat shielding are not gonna keep the car from running...but when it is pushed to its limits.... they help keep it reliable and consistant....
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...hmmm...^^^^ I run my current 240Z at HPDE and TT events once a month...I run autocrosses about once amonth also. I use factory 4 screw Hitachi carbys with no mods... the car puts out 138HP at the wheels..It pulls great all the way to 6500 RPMs...for as long as needed..well over 120MPH...I have absolutely no issues with cut out in corners...Roebling, VIR, CMP, Rockingham...brakes are my biggest issue..not fuel delivery.
I used to guess at mixture settings until some dyno runs with an AF meter showed me that the mixture varied GREATLY under different conditions...I installed dual AF meters with twin displays....this took ALL of the mystery out of tuning my car...It runs reliably,cleanly, and powerfully. I must say that a lot of the "advice" I had received over the years about alternate fuel pressure and float levels was a bunch of BS. If you have everything up to factory spec..and tuned properly you will not have cut out problems under any conditions...with Hitachi or the siamesed/triple carbys....
I just went through this with a fella who had the same high RPM cut out you describe...It turns out that the cut out was not related to RPM as much as it was engine load and duration...it just happened to show up around 5k RPM under most circumstances...The problem was fuel flow rate...the steel lines had rusted around the battery tray area...a small pinhole had allowed rust to penetrate inside the line and apparently plugged the hole behind it...rust built up inside the line and almost closed it off...When I performed a pressure test on the lines the rusty area blew out and the problem became evident...once the steel line was replaced the fuel flow was back to normal and factory settings performed wonderfully....
If you want to do yourself a favor...get some time on a dyno..with a working AF meter in the exhaust....It will tell you exactly what is happening under various loads and RPMs.
A note about air cleaners....The factory air cleaner is fantastic...there is nothing but noise to be gained by removing it and going with "pop" cleaners...or open element filters....I tried several different common filters and found that none of them made more than a 2 HP difference from stock...
The stock filter housing covers and contains the element...it is much less likely to catch fire and burn in that steel box than when it is exposed to the free flowing air in the engine compartment...besides...when the hood is buttoned up and heat builds up...the factory cleaner will draw cooler air in from the front of the car...the "pop" filters just suck hot air off the headers...
Triple carbys obviously cannot use the stock air cleaner...but "TWM" makes an airbox to fit them that uses a single cone filter on the snorkel tube....
Apparently Prieth took my comment about professionals the wrong way....I will not vouch for the average mechanic...HS education with some community college does not count as an experienced mechanic... but the manuals assume you know what you are doing..they are not written to cover all the bases for a home tinkerer.... If you have not done it before...get help from someone who has...there are soo many finer points to doing any job correctly that a newbie cannot hope to get it all right the first time...unfortunately...the fuel system is not very forgiving..and it is very dangerous if you do it wrong.
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ok...engine fires are caused by fuel....fuel needs to get OUTSIDE the carby to get enough air to burn. YOU HAVE A LEAK...or an overflowing carby....
Were the aircleaners soaked with fuel when you had the fire???
This is common and could be the result of sticky floats...overly high fuel pressure, bad inlet needle valves....
If you have "performance" carbys...a common "upgrade" was "Grose jets"...Grose jets HATE gunk and trash in the fuel...They are great...until they see dirt or varnish.
A common newbie mistake is cutting new rubber lines and failing to clean the little bits of rubber off the cut ends...another common mistake is removing and reinstalling hoses on BARBED nipples...the sharp edges of the barbs lift little slivers of rubber off the inside of the fuel lines...when you push the hose back on....the slivers are scraped off and end up sticking the inlet jets open.
Soo many people miss the little things and screw up their cars....
A good mechanic is not just able to follow assembly manuals...he is also an expert at proper handling and assembly of individual parts...there is a lot more to it than the manuals explain...
As far as your car is concerned....A complete fuel system rebuild is MANDITORY!!!!!! You absolutely MUST determine what caused the malfunction. You must also treat the other carbys as if they were exposed or prone to the same problem. Even if you find that the original problem was unique to only one carby....YOU MUST REBUILD ALL OF THE CARBYS NOW that they have been exposed to heat of the fire....All engine parts get hot....but the fire could have heated things far above their failing point.
If you brought the car to me to fix...THE FIRST THING I would do is check fuel pressure...It does not need to be more than 1.5 PSI at any time....to ensure flow through undersized fuel lines you may hear of people running as high as 4 PSI...but this is unnecessary with a well thought out fuel delivery system...raising the fuel pressure will not make MORE POWER....It just makes your car burn.
In any case...Fire is one of the most painful ways to die....It will also completely destroy your car...do not dick around with this problem...take it to someone who knows how to work on performance carbys on older cars...A Ferrari dealership would be the PERFECT place to find folks who know how to properly work on the siamesed sidedraft types.
On occasion.... an improperly set spark advance will cause a backfire into the intake manifold while attempting to start the engine....with the extra fuel pooling/wetting in the manifold at cold startup...a fire can occur.....A carby/manifold fire of this type is easy to extinguish by contiuing to crank over the engine..... It may startle you....but simply continue cranking until it starts....once the engine starts...blip the throttle to draw the flames into the engine...the fire will almost instantly go out... Of course...if your aircleaner is on fire...you better break out the extinguisher...you dont want ashes and bits of paper or foam going into the engine.
A little list for you to check....
1. fuel pressure
2. inlet screens on each carby....functional and in good condition as well.
3. proper handling and assembly of all hoses and fittings....from tank to carbys..This also involves flushing the system into a clear closed container and checking for bits of trash...even one little spec can cause you problems.
4. check condition of fuel filter...look for bits of trash or sludge that may require draining and cleaning the fuel tank.
5. test flow through feed and return lines....a plugged return line can cause overpressure.
6. dissassemble each carby and check condition and operation of float and needle valves...in case you dont know...this involves blowing through a tube attached to the inlet and moving the float until it closes the inlet valve...stopping the flow of your breath though the tube...check float height at the point it actually stops flow...not where it "feels" like it is closed...you must actually test this while blowing air through the inlet....Something like aftermarket "Grose jets" will render the dimensions in the manual useless unless you actually test the jets while blowing air through them.
7. check the condition of the engine mounts and tranny mounts...A bucking engine can literally shake the floats loose in the carbys...although this is more of a problem with off road/all terrain engines.
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I have put a few exhaust on 240Zs.
It is a good idea to replace your engine and tranny mounts BEFORE you add your new exhaust...things may not line up properly when you attempt to replace them later on.
There are a variety of headers out there...some will require custom stud lengths..most will work with the stock studs...some will require a great deal of trimming washers to even the contact between the exhaust and intake manifolds. They are all prone to flex and breakage of the outermost studs.
It is a good idea to add a flex joint right after the 2-1 collector...this will take strain off the studs..but it will require extra support aft of the flex joint.
The factory placement of the resonator just after the collector was done to break up resonance in the long straight run to the rear. I think this is a good idea...It has been suggested that it may add some midrange power when compared to a similar exhaust without it. Whatever you decide to use..it should be a straight through design...and it should be at least 8" long and significantly wider than the rest of the exhaust tubing....similar results could be obtained by placing the resonator at the aft end of the long run( just in front of the differential)...though the forward placement will even out flow through the entire run.
Muffler choices are more personal...A Dynomax is a very popular muffler for Z cars. It has a sound that is similar to the stock Z-car growl...You can keep one factor in mind when making choices...A straight through design will ALWAYS be louder than a baffled chamber design.... I have heard a Z with a NA L28 with 2 straight though mufflers...one in the resonator location and one in the normal rear location...with 2.5" tubing it was LOUD!!...2 does not make it much softer than just one.
When deciding tubing sizes...2.5" is the most popular....3" may not maintain enough gas velocity at low RPMs to scavenge properly...It has been said that Z-cars with 3" tubing sacrifice some off the line pull...I have never compared 3" with smaller sizes on a street car...most 3" systems are on race cars that do not need the low end "street" response.
last item on the list.....A "resonator" exhaust tip can be very effective at damping the sound as it leaves the system...this can slightly reduce the noise.... most systems end with a short section of straight tubing... that can set up a popping resonance that actually increases the noise...
Make sure you beef up the factory hangar points when you replace your exhaust...most of them are held on by 2 small spot welds...they are prone to breakage.
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I would not have gone down without a fight.... then I would recoup any fines and or additional jail time by sueing the **** out of Best BUY. I WILL NOT be wrongly arrested without a major fight. I will beat the **** out of the security guard/cop before I go anywhere under those circumstances.
Citizens of this country should not allow themselves to be arrested for dumass shiat like this....It is worth the battle and the bruises. I have done it before and gotten away scott free.....the officer and I suffered from a few injuries...but I guarantee the officer has more respect for his fellow citizens now. Just dont get your *** shot when his backup arrives.
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I have a few comments here....assuming this is an L-6 and not a V-8 Hybrid.
1. The fuel filter is supposed to be placed BEFORE the mechanical pump. This is a general rule to follow here.
2. There is supposed to be a return line or your fuel pressure may surge. Go get another fuel rail that is functional.
3. You have not mentioned any evidence of contamination in the fuel filters that keep failing... If your tank is full of rust and water...I would not be surprised that you have gone through a whole box of filters in a few minutes run time. Nissan was soo thoughtful to have placed a DRAIN PLUG on the bottom of the fuel tank. Drain it and have a poly liner installed.
4. Go get a Haynes manual....they tell all
You sound like a likely candidate for a FLAMING DEATH... The carby fuel system is as simple as they come... You should not drive it until someone with experience can take a looksee.
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Quick Electrical checklist....for 240Zs
1. Make sure the original fusable link is in place... on the starter +terminal.
2. Any added circuits should be connected to the battery +terminal with a fuse at the battery.
3. Ground the engine block to the chassis with a heavy guage grounding strap...no lightweight body ground crap...we want to see big meaty wire.
4. make sure the battery ground -terminal has a connection to the firewall near the battery.
5. check and/or clean the lighting ground terminals in the rear clip, the dash areas, and the front clip. These are common problem areas...you might get a few more watts of headlamp intensity.
NOTE: Adding circuits that bypass the original harness (attached to battery +)..... will cause the AMP guage to read a high charging condition when using the new circuits.... Just use a volts guage instead.
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I see the o2 bypass circuit...
i can only assume that it is feeding voltage from a thermocouple sens wire back into the o2 sensor wire....as far as the heater element...that is obvious..although I would use a 50 watt resistor and keep it away from flammable materials.
some people seem confused about the operation of these sensors...
The actual sensor outputs voltage to the computer...anywhere from 0.01 volts up to about 1.0 volt....the only difference in wideband and narrowband sensors is the range of measurable air/fuel ratios. the wideband picks up a wider range without spikey voltage swings.....
as far as the sensor just operating on and off modes in a repeating pattern every second...that is your cars computer in closed loop sensor mode doing that.....the sensor will simply track the actual a/f ratio...the computer is alternately forcing the engine to run rich then lean over and over again....all this happens at idle or part throttle....look up closed loop mode in google.
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Ohh....My manual for my 1972 240Z says to use 93 or 95 octane fuel. I imagine the 1970-71 models would require 95 octane...as they had the highest compression of any Z car ever.
High octane fuels have been around since WW2...
Consumer grade gas was lower octane in the 40s and 50s because the average Joe's car had a very unsophisticated motor. Folks who drove high performance cars went to the airport for gas.
High octane consumer gas became more expensive and harder to find after lead was banned...
You can purchase gas at your local airport and pump it directly into your car IF.... you have no restrictor plate in your filler tube.... The rule is...you can only pump avgas into a vehicle that can use the large sized filler tube. No gas cans...no funnels allowed... If your local airport operator says no...just mention that you can actually fit their large sized filler into your antique car...with no funnels or other aids. Be careful when you pump from avgas pumps....they flow about 5 times the rate of a consumer filling station...
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There is a neat program about the history of gasoline....on History channel...I think....
Moridin has the closest correct answer....
Heptane = 0 octane rating
Octane = 100 rating.
This is only the basis for our "octane rating". It has nothing whatsoever to do with the actual compounds in the fuels we call gasoline.
gasoline contains many diffent carbon chains.... In fact current day gasoline may contain varying quantities of compounds anywhere from 6 to 10 carbon chains long.
These compounds have been "cracked" from longer molecules during the refining process using heat and catalysts.... In fact there may have been several cycles of cracking and recombining of these molecules to get the mix we call gasoline.
The cracking process was developed to get more "gasoline" grade fuel out of each barrel of oil. It has been modified to get not only more gas...but better gas for high performance engines.
The actual "octane" rating for these compounds has been further modified by a process that "joins" the loose end of the carbon chains in a RING shaped molecule that turns out to have enormously higher octain ratings than the linear chains.....although it is the same chemical.
Additives like Tetra-Ethyl-Lead further improved octane ratings as the need for detonation resistant fuels increased with high performance aviation engines in WW2. Countless other compounds have been developed since then to replace lead with less hazardous substances.
Other additives help stabilize fuel, clean the engine, and reduce emissions.
Most importantly.... ALL FUEL OF A GIVEN RATING IS THE SAME....NO MATTER WHERE YOU BUY IT IN THE USA. All the distribution companies use the same infrastructure to pipe the same fuel as everyone else.
Ahhh....but you say that Amoco fuel "smells" better....or soandso fuel burns better...Yea Yea Yea...There is a difference at the pump....but the only real difference is in the ADDITIVES that the individual fuel companies put in their alotment of gasoline...that is done locally at the depot where the gas company fills it's trucks....
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I just received a new set for the L24 from Motorsport... They are bagged from nissan and contain a whole laundry list of various lengths and part numbers combined into one set. There are at least 3 different length studs and a few bolts along with all the nuts and washers. It was pretty expensive as I recall.
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Great results are always very satisfying....Goo job!!
I will say that I have been through a number of "upgraded" fuel system components....some are not as good as they seem at first.
I grant that the original intake may not have been flowing enough air for 6000+RPM torque numbers....but the fuel system should have been able to keep up with most of the powerband.
Many times people "upgrade" to a new fuel system when the original system is broken and malfunctioning. Under those circumstances the improvement seems huge...but usually it is not that great.
Keep in mind that many folks have to consider the Inspection Nazis once a year. Original equipment has great value to these people.
About the 4BBL conversion.... It seems capable of flowing more than enough air and mixing in great quantities of fuel. But it can have some drawbacks....
1. poor fuel distribution between cylinders....can cause premature wear of the rings on some cylinders...lean detonation on others. Not that Nissan did this right either....
2. gasoline can pool below the carby and "run" into the engine on hard corners...Auto crossing on a hot day can make this a nightmare.
3. you wont pass inspection in most cities
4. I dont like the feel of the primary/secondary downdraft carbys with these motors.
That is subjective...but a good set of S.U.s with tight shafts have a WONDERFUL linear "feel"....very predictable when feathering the throttle in sweepers...or getting power on quickly and smoothly comming out of a turn.
I have a set of dual Weber DGV carbys, twin Cannon manifolds, with the jet kits, 2 rebuild kits, and a spare carby brand new in the box. I ran this set up because my SUs were worn out and this seemed like an improvement. This is all sitting on a shelf now.
3 years later I got a fresh set of 4 screw SUs and removed the stupid Weber downdrafts. I spent at least $1500.00 and COUNTLESS man hours trying to make those carbys do what the SUs just do naturally and better.
Good luck with the 4BBL conversion...I am interested in how they hold up for you in the long term.
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LOL...that assumes your significant other isn't already restrictive enough.
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I hate these people who hawk useless junk that can only hurt performance or do nothing at all.....
Give me a break....It creates turbulence in the fuel line....and this is supposed to have some chemical effect down the line after the fuel has passed though any number of other turbulent restrictions...including the spray nozzels of the injectors... I bet I can get the same results by driving real fast and "shaking" my fuel tank. As far as the "photo" proof they provide....how about a frame of reference...they can just as well make that claim of soot reduction and really only mean that "we cleaned the paint when we installed the device...and then we took this photo".... The bus pic does not mention that the engine was in too high a gear in the smokey picture...and the clean picture has it in neutral.
You can stick one on the end of your Penis to enhance your sperm too.
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ummmm....evidently you guys are not looking at the same pics....
The linky shows me 1970-71 round top, 4 screw Hitachi/SU carbys.
with the air cleaner....those things are worth $300 if they are indeed in good shape. If he had the N46 manifold they would be worth more.
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hard vs soft mounts....hmmmmmmm......
You guys should really keep in mind that cast iron is a lot stiffer than sheet metal.....
sheet metal is quite flexible. the whole damn car is made of sheet metal....
If you mount the front of the diff solidly it will simply flex the sheet metal....
I can gaurantee that the car will "tear" before the diff case or the solid mount breaks.
If you want to test this I will be happy to hook a cable up to your solidly mounted diff from my 1 ton 4x4. I bet if I floor it the diff will come out with the mount and moustache bar still in one piece.
as far as noise is concerned.......You are now flexing the sheet metal in the floor of the car...you can think of your car as a speaker cone...the voice coil is the is the differential and its mount...hard mounts will transfer not only more energy...but also a MUCH wider range of sounds.....Also the rubber in the mount acted as both an insulator AND a dampener....you could add your own damping materials to the inside of the car to reduce noise. A heavy but flexible weight attached to either side of the tunnel would do wonders for noise.... also try putting your original 50lb spare tire back in the well..my 1972 spare fits in with the rubber pressed against the perimeter of the bottom of the well....it is very heavy and flexible so it cuts the noise wayyyy down...it can better balance your car as well.
fattest road race tire and wheels combo for stock spring perches
in Brakes, Wheels, Suspension and Chassis
Posted
Pop N Wood.....
is your car lowered?
have you added caster, camber, toe to front and rear tires....all of these things will change the way the tires sit in the wheel wells....
It is interesting to me that soo many people have different experiences with fitment of tires.....Obviously suspension changes will affect clearance....but I think part of this is due to the fact that our little metric tire size system sucks major butt....You look at 10 different 225/50/15 tires and you will find 10 completely different sized tires.........even on the same size rim.