pkz

A little while back I wrote code for calculating stress and retention force for press fits. If you know the nominal outer diameter of the valve seat I could do a quick calculation to find a suitable range of interference fits, then use that to determine hole/seat sizes. Also, a quick calculation indicates that about .00065" interference is lost when the head expands. I assumed a valve seat outer diameter of 1". CTE Chromoly (4130) 7.6*10^-6 in/in degree F CTE Aluminum (6061) 13*10^-6 in/in degree F T1 (room temperature) = 69 degrees F T2 (High Safe Operating Temperature) = 190 degrees F ValveSeatDiameter=1" Change in interference=(CTE Aluminum - CTE Chromoly)*(T2-T1)*ValveSeatDiameter What hole diameter tolerance are they hitting when they post machine the heads? What about on the valve seats themselves? EDIT: Also, you mentioned that any time you press something in you are shaving metal. My understanding is that unless the yield strength of one of the materials is exceeded, the press fit does not remove material or permanently deform either the seat or the head (at least not a significant amount). I would argue that using a press fit probably isn't bad practice unless there were other errors in the process as well.

What material are your valve seats made of? And what interference did you spec?

NW240z I'm interested! I just need the driver's side (no pigtails) after taking a closer look. My passenger side one is in better shape than I thought. Pictures would be great.

gogriz, my Z is a 73.

http://i45.photobucket.com/albums/f59/trygon21/IMG_3882.jpg http://i45.photobucket.com/albums/f59/trygon21/IMG_3885.jpg http://i45.photobucket.com/albums/f59/trygon21/IMG_3887.jpg http://i45.photobucket.com/albums/f59/trygon21/IMG_3886.jpg Willing to trade for that driver's side tail light if you've got one that's uncracked

I've got one from a 73. Has all heater control switches too if you're interested. Missing the knob for the fan. PM me with an offer?

Looking for a set of 240z tail lights. Would also be interested in purchasing just the driver's side tail light if you only have the one. Located in San Luis Obispo California.

I accidentally started a welding fire in my garage in January when welding on a bracket which was going to hold the existing Z throttle shaft in place. I learned the hard way just how important it is to have your fire extinguishers checked- mine didn't work and left me scrambling. I put the fire out with a hose in my backyard, but not before it roasted my fender and alot of my engine wiring. The old flattop carbs went back on the car for a while in an effort to get the car back on the road as soon as I could. Since I had the six carbs off the car I decided to spend some time to clean up the setup. I bought a spectre throttle cable which I'll run directly to the throttle arm. I also made the slide throttle positions relative to one another- Originally I had the single throttle shaft tapped and screwed in the individual slide mechanisms, so the mechanism wasn't adjustable (couldn't think of a surefire way to make it adjustable at the time). Now I've used set screws to hold the slide mechanism to the throttle shaft. In order to adjust them, I have to loosen the set screw, then retighten when they're set correctly. Not quite as easy as with triple webers or stock carbs, but overall not too difficult. I decided to repaint the intake as well. After using a grinder wheel to clean up some of the rough edges from before, I taped off the area where the carburetors mount to the upper plate, then used a few passes with vht paint from oreilly. I'm really happy with the results.

I would be willing if the opportunity arose- however, most members here advised me to go with a male mold so I don't know whether I'd have alot of interest in the female one I printed many months ago. Progress has resumed however- just more sanding.

Looking for replacement fenders, headlight buckets, and hood for my 240z. I'm located in the San Luis Obispo area (93410).

The mold's been sitting in my room for the past few months- I spend an hour or two sanding on it when I can, but haven't made alot of progress (mold prep takes ages on something like this). It doesn't help that I've got a couple other projects going on as well- tail lights on my 240z just went out, been working on some custom engine stuff as well. All that and school has really put this on the backburner. I'll keep updating this once I make a little more progress. Hard to prioritize it over school and the mystery of my taillights though.

I have a broken clock I'd be willing to part with. I've also got fuel and oil/temperature gauges I'd be willing to part with (considering replacing all of them with aftermarket). Send me a PM

I'm looking to buy 2 used four point racing harnesses. I don't need them to be FIA certified, and they can be past their expiration year for track racing. I like takatas, racecraft, and schroth in particular, but I'm working on a tight budget so anything will work. Also, I would strongly prefer centerlocking harnesses. Let me know what you've got. Thanks for your time Z community EDIT: I previously stated that I would consider 6 point harnesses or unmatching sets but I decided I'd like to run a matching set of four point harnesses. Email at mv.pkragen@gmail.com or respond here. Located in San Luis Obispo Area (93410), central California. Could also accept shipments to 94507 (East San Francisco bay area).

Email sent- Info would still be appreciated as I'm working on a tight timeline and limited budget.

Hey everyone, I've got a favor to ask. I have a 1973 240z and I'm looking to remove the brake fluid switch. My existing one was damaged in a fire which destroyed the internal components of the switch, allowing the two brake circuits to mix- so in the case of a leak in just one of the brake circuits, my entire brake system will fail. After some searching I have found that brake switches are very difficult to source and also very expensive when they do come around. I'll be searching parts cars for one in the long term, but I'd like to get my car back on the road in the meantime. Here's a link to the part I'm talking about in case there is any confusion. http://www.zcarsource.com/brake-fluid-switch-240z-260z-280z-70-75-used_8_77812_65000.html Since I'm having such a hard time finding one of these, my plan is to remove the switch entirely and replace it with a brake tee for the front brake system and then run the brake line for the front brakes to the tee, then run the rear brake line directly to the brake proportioning valve. What I need then is to find the length of rear brake line I need to run straight from the mc to the proportioning valve (the red line in the drawing below). Unfortunately, I'm currently a student in San Luis Obispo and my car is up in the bay area, so I can't measure out the length of brake line I need. My plan is to do the repair next weekend, but I need to pick up the brake lines before I head up to the bay on Friday. So, the favor I'm asking you- Z community, is for someone with a 240z to measure the length of line required to run from the front of the mc to the brake proportioning valve (again, it's the red line in the picture)- you could mock it up using a coat hangar or whatever method you think works best. If you could also measure the length of the stock line running from MC to the brake fluid switch (green) that would be very helpful, as mine has a hole in it, but if not I may be able to find that by searching around. The length doesn't need to be exact as I'll be purchasing pre-flared lines from O'reilly- I just don't want to buy a 3 foot length if i only need 2, etc. (Rear brake line- Red, Front Brake line- Green, Brake Tee Fitting- yellow) Thanks for your help everyone! PKZ

Have someone inside the car press the gas pedal to the floor, while you watch the throttle movement at the carbs. Then compare it to the amount it moved when you blipped the throttle manually. If it moves less (or not at all) then there's something wrong with the throttle linkage. If it moves the same, then you can move on to engine settings like timing, etc. Given your situation it doesn't make sense to start messing with the tune until you've confirmed the throttle linkage is functioning properly. Just my thought

[sharedmedia=videos:videos:286] Got the video up! Sorry it took me so long. The wideband sensor goes in tomorrow.

I set the initial advance to 10 degrees today and the engine idled really well. Started tightening the distributor clocking bolt and my distributor support snapped. It wasn't a clean break- definitely fatigue, so I guess I'm lucky it didn't fail while I was driving. I flipped around the plate and drilled a hole in the other side of the distributor support so I could hold the distributor in place- until the replacement comes. I spent some time setting up the throttle linkage today- I kept as much as the existing linkage as I could, without drilling or cutting it at all. Just in case this setup isn't drivable within the next couple weeks I want to have the dual flattops (and their throttle linkage) usable so I can drive daily. Not planning on it coming to that though. I ordered a wideband O2 sensor which should be here in a few days. Then I'll be able to dial in the tuning much more efficiently. Throttle response right now is pretty sluggish. PS- video coming in the next couple days

After grinding down the T- fittings I don't have any fuel leaks (the stock O rings seal really well) and since the carbs are all pretty secure and the T-fittings are squeezed between two adjacent carbs, so they are very secure. Without jb weld the T's are free to swivel, which makes installing fuel lines much easier. I welded on some extra material to the head-mounting flange, so the header washers hold the flange down nicely. Thanks for the advice gareth, it worked great. My engine idles decently now. I'm going to install a vacuum fitting for the brake booster on the rear manifold tube. I'd like to set up ignition timing advance- like most webers, the mikuni tm40s don't have vacuum ports, so I'll have to come up with an alternate solution. From some searching the archives I have a few options: 1- set up a vacuum log on my intake manifold. Ideally for this to work I'd need to use at least 3 tubes to prevent vacuum pulsing. 2- Run an electronic distrubutor (123 ignition etc). This would be the way to go but they're pricy, and maybe not completely necessary for a N/A setup. To my understanding, these run about 400$ for a standalone ignition setup. 3- Change the mechanical advance curve (new springs). I might not be able to achieve the level of control that the vacuum advance offers, but this would be pretty simple and may be a good "close enough" option. 4- Run the existing system with no vacuum advance and adjust the timing accordingly. Drivability under 3K rpm will suffer, as well as gas mileage. Given that this is a street car, My first choice (unless there are other ideas) is to change the mechanical advance. My current distributor has a crane cams xr700 optical pickup but it otherwise stock (I'll do some more reading and figure out what year). EDIT: Still weighing my options on ignition advance. Read this post about vacuum advance on the Zcar forum. http://www.zcar.com/forum/10-70-83-tech-discussion-forum/286774-pure-mechanical-timing-2.html . Mechanical advance will probably result in something less streetable than I'd hope for.

Got the car to start yesterday- wouldn't rev under a few thousand RPM without sputtering out and dying though. I'm going to weld on extra material for the manifold washers to compress to the head today- then try again. I also reconsidered using permatex sealer on the fuel fittings. I think I'll be better off grinding down the diameter of the plastic T fittings so that the original O-rings fit back on. From what I've heard, anything that relies on a permatex sealer alone (ie not in addition to a threaded connection) to seal will eventually fail.

Drilled and tapped the throttle shaft today. Tested out the throttle mechanism using a pair of pliers- everything lined up pretty well. Then I cut out the holes where the header interfered and was able to set everything in place- only to realize I drilled the head-mounting holes in the wrong location. I used the exhaust-intake manifold gasket as a template to mark the holes, and accidentally used the exhaust holes. Fortunately it wasn't anything that wasn't fixable. Drilled new holes, and the old ones aren't in the way of anything- I'll probably cut them off later once I get to making everything look nice. Gareth- how did you secure the bottom half of the head-mounting flange? There are no holes for the original manifold- the original manifolds are .5" thick and are held in using a thick washer that also holds the header/exhaust manifold in place. Right now my carbs are only held in by the top few bolts, which I'm sure is just asking for a vacuum leak down the road. And finally, some pics: Tried starting it this evening- ended up setting the carbs on fire with starter fluid- scared the heck outta me. it was freezing in my driveway... Tomorrow I'll take another look once it's light out. I suspect I have fuel leaking from somewhere, but it's impossible to see in the dark. I can already tell I'm going to have to rework the T-fittings to accept the fuel lines better- they keep falling off way too easily.

Today I set the throttle shaft in place and set the rest of the carbs in place. Side view of the carbs: I used a cutoff wheel to grind down the plastic T-fittings so they would fit with the reduced carburetor spacing, then removed the O-rings and sealed the fittings using silicone- I didn't have room to place fuel elbows in between the carbs.

More progress. Cut all the tubes and mocked everything up... My mig welding could use some work... Flange/carburetor adapters came in. Bought 6 for under 50$ on amazon, had to shop around to find them cheap enough. Took a risk on some generic ones but they fit great. Two of the adapters installed: First two carbs mocked up. Matched up well considering all my measurements were marked with a sharpie and a ruler. Side View. Tomorrow I'm going to set up the remaining carbs and set the single throttle shaft in place. Then I'll get to work shaping the carb mounting flange (right now it looks like it belongs in a Mad Max car).

I finally made some real progress today. I cut the intake manifold flanges to size and drilled all the holes. Pretty simple compared to some of the stuff I've seen on this forum but it felt good to get back in the shop. The last few days I also had a bit of free time and made an actual 3D model to verify hole spacing/clearances. I spent alot of time double and triple checking my measurements, and made some tube cutting templates as well. Tomorrow I'll be back in the shop to cut tubes and start welding. I hope to have something resembling this by the end of the weekend. Classes are finally over, so I'll have some time to spend in the shop.

The black plastic pieces at the bottom of the carbs are the fuel T fittings. So far I haven't found anything for different carb spacings, but I think it might be worth checking a local auto parts store to see if they have anything (especially since they'll probably let me test fit it against the carbs. If nothing fits then I'll be a little stuck, because simply flipping the carb pairs around won't fix anything in my case (I'll still end up with two fuel inlet ports right next to each other because I have multiple carb pairs). I think regardless I'll try and find a brass fitting and toss the old O-rings, in my mind they're just a leak waiting to happen. Also, does anyone know the spacing center-to-center of triple weber carbs offhand? I know the spacing between carbs in the same set is different between two carbs from different sets- if anyone knows either or could take a measurement for me that would be great. I'll use the total spacing as a reference for my setup. Tony, Gareth- the TM40s are very similar to the HS40s- HS40s are the smoothbore configuration of the same carb, as was mentioned. You are both right- they don't have power valves but they do have accelerator pumps- needless to say setting these properly is pretty crucial to prevent off-idle lag. Tony, what's your reasoning behind the 2X piston size for a 4 stroke vs 2 stroke? 2 stroke will have the valve open twice as often vs an equivalent four stroke (ie the frequency is double), but where does doubling the piston size come into play, out of curiosity? Is there a functional difference between doubling piston size and doubling the overall displacement by some combination of bore/stroke? Sorry to get off topic- but I'm very curious as to why this is. Thanks.