heavy85

I think this has been hi-jacked by 2.5" vs 3" debate so to continue that .... let me start by saying I have no first hand experience with turbo Z's but from what I've seen from CFD (computer analysis that models fluid flow) of air systems in general, the MAJORITY of pressure drop occurs at the bends so the larger the bend raduis and lower bend angle the better. From a whole system perspective little of the pressure drop occurs in the straight sections unless it's virtually all straight or the straight is relatively very long. Angle was mentioned above but not bend radius which might even be more important than the actual angle. I'll guess that a swooping 2.5" section would be better than a tight 3" section but you would probably still want the 3" from then on because of the relatively long straight section to the back. Main point I guess is to consider bend radius not just angle and minimize the bends rather than maximize size. Again this is all theoretical so take it for what it's worth as it applies to 1/4 mile times. Cameron

Jeff - I think I understand but do you have any pics of what you are describing? If I understand right you are actually removing the outer rocker and putting in a new piece behind it (the piece that's sandwhiched between the inner and out - I've seen the three layers of metal in the squashed lip on my car) then putting on a new rocker? Since mine aren't rusted out I was not wanting to replace the whole rockers but I can't see a better way around it. For me its really just that the lips (all three) are squashed. I wonder how much rigidity your fix would add to the rockers and thus the chassis in general especially if you were to extend this piece back instead of just under the door post .... hmmm Thanks Cameron

As many cars have been, mine has been subjected to countless errant jackings. Although there is virtually no rust the entire underbody - virtually every square inch by the looks of it has at one time or another been used as a jacking point. The floors / frame rails can be relaced (thinking along the lines of subframe connectors anyway) and that's pretty obvious what to do, but what about the seam where the floor / inner / outer rockers meet. What I'm referring to is the very bottom of the rocker where the three panels come together and for a lip - mine is squashed down in several spots. I'm afraid if I try to bend the lip(s) back out they will crack (at least did on my old GTI when I tried it) and it's just one of those things that altough not structural it just bugs me and I can't see an easy solution. Any ideas? Thanks Cameron

My daily driver SVT Focus (Z is only a toy - still need something to get to work and through the snow) has factory 17 x 7 with 215/45's and I really like them but still have a hard time getting over how little sidewall there is - like a big wheel wrapped in a rubber band. Never had problems with them and we have bad roads being in the midwest. Cameron

I had something similar happen when I put my first Z engine back together about 15 years ago but mine was a carburated (sp?) 260. Basically it would run fine for about a block then die and not start, wait a while and it would run fine for another block then die ....... you get the picture. Ended up being the fuel pump - same as the ECM thing mentioned above would work great for a while then overheat and once cool would work fine again. Hope that helps. Cameron

I'm with TimZ on this one as I've never bought into the slower water transfers heat better. In developing cooling systems for large off-highway machines I'm pretty sure this is not a consideration ... but I'll check. Preventing cavitation sounds more reasonable to me. If you have an airflow restriction problem then I doubt water flow would really help since that's not the limiting factor - no matter how optimal the water flow is if you dont have the airflow it really wont matter. The counter intuitive thing about centrifugal pumps - flow is proportional to the power of pressure (squared ... cubic ... dont remember) so adding restriction will raise pressure and in the process lower flow much more (again raised to a power). Net result is you reduce the power the pump is drawing (power = pressure * flow) despite raising the pressure! This is an issue on for example electrically driven fuel pumps where if the pressure gets too low the flow skyrockets and consequently you overload and burn up the motor.

Thanks - it makes sense (spel?) that those would be vents for the floats I just wasn't sure exactly what they were for. In that case then definitely they should be vented to the airbox. Now that I know what they are I need to add a couple extra holes to the baseplate otherwise those vents will be blocked Cameron

I'm in the process of building an airbox for my tripple Mikuni's and wonder if what looks like an opening just above the throat is really anything or not. Can I just bolt the airbox on and cover these up or do they need fresh air for some reason? If I remember it seems that when I rebuilt them I could fill this cavity with carb cleaner and it would run out somewhere else like it was suppose to bring in air for the choke or maybe vent the float chamber or something? Thanks Cameron

I am in the process of freshening up my F54 / P79 L28 (cam, shaved head, tripple mikunis, MSD, etc) but was just given an l24 with an 80's turbo set-up on it and am wondering if I should build it instead. I know the torbo engine has been sitting on the garage floor for at least 12-15 years and it originally came out of a 240Z because the car was wrecked. It's got a Rajay turbo (compressor looks perfect, turbine is oily with a lot of carbon build-up) on a pull through single SU - the SU bolts directly to the turbo inlet. Long term down the road I would really like a turbo set-up but was going to be content with my existing engine for a while ..... but before I send my l28 in for a valva job is there any value in trying to get this turbo set-up going? Thanks Cameron

I posted this on the 6 cyl board since it's for an L6 but didn't get a response. It seems like there are some knowledgeable people over here and I dont think it's specific to Datsun engines so I'll try here. Here it is: I just got done porting my P79 head (well just gasket match and smoothed out the casting marks) and am starting in on the valves. I've searched but not come up with any specifics other than 'polish valves' so what should be the surface finish on the stem, the top (port) side and the bottom (chamber) side - I'm thinking there may be a difference but dont know? I found I can get a mirror finish by stepping through several grits of sandpaper and ending with metal polish but where should I stop? Also, there is a chevy bow tie-ish mark cast onto the bottom side of the valves -should I grind this off to make is completely smooth or just leave it? The reason I started in on the head was from the carbon build-up on the valves in the first place so I'm mostly trying to reduce that in the future but any performance gains would also be nice. The head had already been shaved and it's got a Schneider cam (I think), tripple Mikuni's, MSD, header, etc ... Thanks Cameron

I just got done porting my P79 head (well just gasket match and smoothed out the casting marks) and am starting in on the valves. I've searched but not come up with any specifics other than 'polish valves' so what should be the surface finish on the stem, the top (port) side and the bottom (chamber) side - I'm thinking there may be a difference but dont know? I found I can get a mirror finish by stepping through several grits of sandpaper and ending with metal polish but where should I stop? Also, there is a chevy bow tie-ish mark cast onto the bottom side of the valves -should I grind this off to make is completely smooth or just leave it? The reason I started in on the head was from the carbon build-up on the valves in the first place so I'm mostly trying to reduce that in the future but any performance gains would also be nice. The head had already been shaved and it's got a Schneider cam (I think), tripple Mikuni's, MSD, header, etc ... Thanks Cameron

I'm confused - I always thought that Z's were nose heavy a bit so it was a good idea to move the battery to behind the passenger seat to help even things out (at least from a static weight perspective but maybe not from a moment of inertia perspective). By the weights given above if anything moving the battery would hurt weight distribution? Can anyone clear this up? Thanks Cameron

Yeah I started to make one like that but then couldn't get to the bolts to tighten them when I added a gusset. I just bent a piece of aluminum but thought it really needed some support. Maybe I just need to offset it further down then maybe the gusset will fit? Thanks Cameron

I need to build a heat shield to place between the headers and the tripple Mikuni's but can't find a good place to attach them. Anyone have pictures or an explanation of how they made theirs. Thanks Cameron

It's in a P79 head from L28 and I was told it's a 'mild cam' when I bought the car. It has a maltese cross on the end with a fancy script S with what appears to be a part # 26119 (this part number is not on the Schneider web site but they do use a maltese cross in their logo). Also stamped on the end is 270.80F with an R and an M stamped on either side of the dowel pin. I'm thinking this means 270 deg / 280 deg but that's just speculation. Not sure what the letter mean though. Lift (measured difference between max height and the base circle) is between .292" and .302" which at first I thought was low but multiply by rocker ratio of ~1.5 and the lift would be between .438" and .453" at the valve. Anyone know if I'm on the right path here? Is it a 270 / 280 deg .450 lift Schneider cam? Thanks Cameron

I read on an old post that Norm resurfaced his rocker arms on his 12 second Z ..... and I dont want to spend the $$ for new ones ..... but I want a new cam ..... got me thinking I should just resurface the one's I've got. Any advice on this - I was kind of thinking to sand down the surface to get rid of the old wear marks then move to progressively finer paper untill it was real shiny. Does this sound reasonable? Cameron

Is that what those barbed fittings on the bottom are for? There is one on either side of the bottom of the carbs but the only thing they would cool is the back side of the accel pump diaphram if memory serves. Also, I dont have a return line but am thinking it would be a good idea to add one. Wouldn't that require a different pressure regulator - one that's a relief valve instead of a reducing valve? BTW - Anyone out there have details or pictures on their heat shield for Mikuni's? Thanks Cameron

I have very thick - maybe 10mm - spacers (insulators) but I do not have a heat shield between the headers and the carbs. I've been thinking about adding one but haven't yet figure out a good place to attach one to. I do know they get hot though because you can't even hold onto the carb linkage! Cameron

Thanks for the suggestions John but it ended up apparently there needs to be a thick washer between the bearing and the nut otherwise the nut bottoms out on the threads before it actually clamps the bearing (yet another half-done previous owner blunder). I simply added a washer and now the nut actually clamps the strut in place and no more noise. Cameron

Hey Tekira - your host site cardomain installed adware (spyware) on my computer when I visited it. I just now got my computer back working halfway OK after reformatting my harddrive! Anyway, since I just rebuilt all the carbs I know they are not dirty. Fuel pressure is OK, the floats are set to Mikuni specs, what else could it be? Does it have to be in the floats - maybe the seats are bad? Thanks Cameron

Yes, I set them up exactly per the Mikuni manual. Adjusted float level and accelerator pump travel to 12 mm and 7.5 mm respectively.

I've got pump-regulator-pressure gauge-carbs-NO return line and the fuel pressure guage reads about 3 PSI at idle. This was all set-up by the previous owner I just rebuild the carbs and am trying to get it all working well. Same deal as you when I park it it just reeks of gas. There is a real strong exhaust smell which is another issue I think and may be partially attributed to some carbon build-up on the valves. The smell I am trying to fix here is a raw fuel smell coming from the carbs. I haven't yet tried to fix the exhaust smell and I know there is a lot of history I need to look up on that. Thanks Cameron

Not from the exhaust but from the engine itself (well the exhause reeks too but that's not my question here). I have an L28 w/ tripple 44 Mikuni's in my 240 and it reeks of raw fuel around the carbs. There are no leaks and the carbs have all been rebuild but it still smells like raw fuel in the engine compartment. The smell seems to be coming from the carbs - all of them. I am only running stacks with no filters but I still would not expect this. Is this normal and any ideas how to stop it? I cant even park the stupid thing inside the garage because it stinks up the house. Thanks Cameron

DaleMX - how much did it cost to ship from Cali to Ga? Thanks Cameron

Clicking on the thumbnails just makes it one grainy page instead of all together but once I clicked on the thumbnails a nice little box appears on the bottom right hand corner of the screen which I previously missed. If I hit this 'expand' button it zooms in to where it's readable. Thanks Cameron