inline6

I bled the brakes and clutch again today. Brakes function, but the booster is not boosting 😉. This 7" kit is available from Zcardepot: https://zcardepot.com/products/power-brake-booster-rebuild-kit-7-inch-240z It looks like the right one to me. Anyone buy and install one of these? My booster looks like to be the rebuildable type that they mention (note red circled area): They are in Missouri, so stuff from them usually shows up where I am in Georgia within a few days.

Not finding needle valves readily available was probably a good thing. I probably would have ordered them, however, I went out to the garage and took the float cover off again and inspected everything again. This time I used about 10 psi of compressed air and checked to sealing. The float was turning quite a bit angled in order to get it to seal. That doesn't make sense to me. I don't get why the floats aren't more level at the point where the needle seals against the seat. In this case, the bottom edge of the float appeared to be crossing over where the side of the float bowl would be (if the cover was on the bowl). Perhaps the side of the float was interfering with the side of the float bowl and not able to rise more to seal the needle against the seat. Though I used the clear tube method to set float levels previously, I repeated that process tonight with this carburetor bowl, and again set the float level so gas came up to a mark I set at 20 mm from the bottom edge of the float cover. Is 20 mm from the bottom of the lid is correct? The needle and seat is working properly again now. I took the car for a another brief 3/4 mile drive. It was not fully warmed up, but it ran a bit better than before at 2.5 turns out on the mixture screws. Assuming I don't run into another issue, I will get it up to temp and try another brief road test tomorrow to see if I will be able to get the mixture close by backing out the mixture nuts a bit more. Perhaps I will need to switch to different needles. I don't know.

Unscrewed the mixture screws one half a turn and fired the car up tonight. Backing out of the garage, I notice liquid on the ground. It was fuel coming from the rear carburetor. Float seems operative. My rear carb needle and seat appear to no longer be sealing. I took it out and blew compressed air to clean everything out. I examined the needle rubber tip and the seat with a magnifying glass. They look new, but when I put everything back together and fired it up again - same thing. Fuel overflowed out of the vent in the top of the chamber. Looking online... and I am not finding needle valves available.

I put 20 weight in. I think I used to run just 10W-30 in the Su's on the track car. This time, I paid attention to the factory workshop manual.

Ok. Front and rear carburetor nozzles are properly aligned. Both carb pistons pass the drop test. Carbs sync'd again. Initial timing adjusted to 17 degrees before top dead center (euro distributor) at 750 RPM. Idle is staying exactly in one place. I drove a couple of blocks again. I haven't hit more than 20 miles an hour. However, the driveline seems quiet. No noises coming from the transmission or the differential. At two turns out on the mixture adjustment screws, it is lean. It idles nicely, but try to give it some gas and it is like you popped up a sail catching a headwind - the engine doesn't want to put out 🙂. When I pull the starter circuit a bit, the power kicks in. So, it appears that my engine mods may have altered the fuel needs a bit from stock. I ran my track car on SU's for a couple of decades... That engine had "some porting", 1 mm bigger intake valves and a header and dual 2" exhaust. If I recall correctly, the SM needles didn't work as well as the original N27 stock needles when I finally got everything dialed in. This engine has similar mods but a "stage 1" Isky cam. It is really quite mild, just has bit more lift. I guess I will play with unscrewing the mixture nuts a bit to experiment with determining what the engine wants. The manual calls for 2.2 turns out. I have them out exactly 2 right now.

Took another look at the carburetors tonight. Neither piston was dropping to a "clunk" in the carb bodies. The needles were touching the nozzles, and that was keeping the pistons from going to their correct locations when doing the "piston drop" test. I was wondering why my idle speed kept moving around! I loosened the nut holding jet bridge and centered it properly on the rear carburetor. Firing it up briefly, the idle is MUCH improved. I will do the same for the front carb and give it another little test drive.

So... I ran into the same thing with the clutch master cylinder tonight. This cylinder was a used part also. It looked to me like it was replaced by the previous owner as part of the fresh work he did to the car. Hmmm - actually, I think that was 28 (plus 6 years in my possession) ago! Anyway, the little valve was stuck in this one also. For any used cylinder, that valve should be checked and lubricated with a bit of rubber grease before installing the cylinder. I was able to get the clutch operational, and the brakes barely so. I need another person to assist to bleed them properly. And it is quite possible that the brake booster is not functional. Anyway, I took it for a brief drive in the neighborhood. It has been about 9 years now since I drove a Z. It's tiny! Turning around to back up, I was struck by how narrow, and also, how little there is of "car" behind me! I was reminded again of how awful the throttle linkage is. It has a lot of initial resistance, so you press a little harder, and then a little more, and then it "let's go", causing more acceleration than intended. As I recall, I will be able to sort that out by adjusting the linkage and bending the gas pedal arm as necessary. Oh, and that exhaust stink. Hahaha! Even when you get them running well, if you spend much time behind the tail pipe, you stink like you've been running a 2 cycle leaf blower. While it starts up easily and has good throttle response, it doesn't sound or feel like it is tuned. When I give it enough throttle to go past 2500 rpm, it acts like it is lean - it doesn't want to rev. I will need to check timing again (static and dynamic), and check set/mixture screws again, carb sync again, etc. Anyway, it runs!

Thanks for that info! So, when I took the cap off, I found that the valve was stuck in an open position (makes sense if that is resting position, as the cylinder likely sat for a very long time and got gummed up/stuck in that position). The spring couldn't close it. In fact, there is a hole in the end of the cap, and pressing a flat punch against the valve, it did not move - it was stuck tight. Stuck in the open position, fluid just moved freely in both directions. The rear circuit didn't build any pressure. I just got back from the garage - I am done for the night. This time I was able to bleed the MC rear circuit with no issue. Then, I was able to bleed all four corners. I seem to have a solid brake pedal at this point. Hurrah - I got something done today after all. Now, I have the clutch circuit to bleed. And then, I'll try to fire it up and drive it around the neighborhood a bit.

Today, I was excited to do some brake and clutch bleeding and then drive the car around in my neighborhood a bit. It was a beautiful, sunny day, and I was looking forward to it. However, it was not to be! I spent 8 hours trying to bleed the brakes instead. The rear circuit would not move any fluid. I experienced this once before with a "nearly new" Honda S2000 brake cylinder. Each circuit has a little valve that operates. I am not exactly sure how it works, but basically, there are conditions where the fluid will move one way but not back. That valve got "stuck" with the S2000 master cylinder. And I recall it taking me forever to figure it out. That experience was fresh in my mind as I attempted to bleed the brakes and the fluid was not moving either direction for the rear circuit. Though I knew I had a problem, I could not figure out what was going on. For my 8 hours of frustration, at least I can share what I finally found out to be the problem. This is the piston assembly for the rear circuit. Unless you are lucky enough to find a new old stock Tokico master cylinder (and pay big bucks for it), then you will likely want to do what I have done hear to ensure that you will not have the same problem. Here is my rear piston assembly. As you can see, I have removed the "cap" to the far right in the picture. For quite a while today, I tried spraying lubricants and blowing compressed air in the holes of this cap. But that did nothing. Eventually, I became frustrated enough that I put it in my vise (with flat metal plates instead of the serrated teeth) and clamped down on the sides of this cap (with the piston assembly sticking up vertically). I grabbed the piston assembly and wiggled it one way and then the other, unsure what would happen. Luckily, the cap is a light press fit to the end of the piston assembly. And yanking one way and then the other, I was able to pull the piston assembly from the cap. As soon as it came off, I knew I would be able to solve my issue. As you can see, there is a spring... and a little rod with a rubber seal on it (the piece with rust on it, second from the left). Some #0000 steel wool cleaned off the rust from that piece. And a brass "pipe cleaner" type brush cleaned the rust from the hole in the piston assembly: From there, I dabbed a bit of brake grease on these parts and reassembled them. I fitted the spring and tapped the cap back on with a small hammer. Now, this little valve works at it should. Determined to not have wasted some much time today, I am going to go out to the garage and bleed the brakes now like I originally intended to do today.

I didn't realize this difference for the 70-71 cars - the valve cover utilizes an O-ring to seal against the oil cap. I was able to get one (had to buy 100!) that fits very nicely! Later Z cars have a rubber gasket on the oil cap instead.

I was able to get one seat finished today! It was difficult to get the seat back upholstery stretched enough. Putting the seat back in the sun and working the material down the frame, as well as from back to front around the side bolsters, I was able to get the front flap on all the hooks. I also was able to run a piece of wire inside the bottom loop on the back side. The hooks now hold onto that wire which runs the length of the rear vinyl piece. Everything is nice and tight! When bending down the hooks, one of them was fatigued and broke. I ground away a spot weld and removed the old hook. I made another from scratch and drilled a hole in it so I could attach it to the frame with a rosette weld. It was tricky welding this with the upholstery on. I used a wet rag to protect from splatter. Thankfully, all came out well in the end - the hook I made is the last one here in the second picture. I also finished the seat brackets today. I had painted them gloss black when I sprayed a large number of parts a while back. To finish them properly, I scuffed them with green Scotch Brite pad, and then used the same SEM texture paint I used on the center console. I shot this at a distance of about 2 feet. And again, sprayed a satin coating on top of the texture, as it has to be top coated. I have never sat so high in a Z! I may have to remove the two plastic spacers under each seat - we'll see. I think I will try to get the car moving under its own power tomorrow - pretty exciting! All I have to do is check the hard line fitting for the clutch and brake system, add fluid and bleed those two systems. Oh, and torque the lug nuts to spec!

I'd like to have the dimensions. I had a NOS one until I sold it a few years ago. Now, I need to fab one. What part number did you use for the round rubber replacements? McMaster Carr?

Some pictures from where I left off last Sunday: It was a battle to get the front edge of the upholstery down far enough to engage the hooks on the frame. As you can see, there is a stitch seam that the hooks are catching. If that stitching wasn't there, the vinyl would simply tear all the way through. The hooks were originally hammered down towards the front surface of the seat back. In order for me to progress this far, I had to bend the hooks to point out from the frame at 90 degrees. When the hooks get bent back down finally, they will again point towards the front surface. If I did that right now, the vinyl I have holding on the hooks would simply slip off. So, it is important to note that the only thing that holds this front vinyl from slipping off the hooks when you tap them down to their final position, is the back vinyl part of the seat back upholstery. When the back vinyl portion gets pulled down over the hooks, and they are tapped down toward the seat front, the back will not be able to slip off. The only reason the front won't slip off will be due to the front vinyl being put on first, and thus it will be trapped under the back part... with the back vinyl portion unable to work loose from the hooks. What I also notice is that the back vinyl does not have any cord, or wire running through the part where the hooks will go through. Because of the high amount of tension, and the fact that "the back has to hold the front also", I am going to run some wire through the back, bottom edge. It is stitched there, so I will be able to run wire through the loop that has been created when the bottom edge was folded over and stitched. With the hooks engaging the wire, the full length of the vinyl material will be holding the seat upholstery to the frame, not just the tiny portions of vinyl which are in engaged by each of the hooks. To get the back upholstery to where it is now, I had to use the sun to warm it up. While I was doing that, I put the seat bottom in the sun last Sunday also, and it really helped improve the look and fit of the vinyl upholstery on there as well. I still only have zip ties holding the seat bottom upholstery down to the frame but they are pulled all the way tight, and I am satisfied with the final look here. So, I will put on the hog rings and remove those, and tap down the metal hooks on the frame to finish out the bottom upholstery installation. Trimming the excess "bar" off of the foam front of the seat bottom was the right call: Hopefully, it will get warm enough today (sun is out) for me to continue.

I still think the replacement seal (#1 in your parts book picture) I bought from Banzai may be thinner than the original. Unsure if that is part of my issue.

Actually, the earlier back plate is the one with the choke cable bracket. So, the car your recently bought has the correct back plate and housing.

Excellent! However, I do believe your orange back plate should be paired with your purple cover. And purple backplate with your orange cover.

Possibly... but I don't see any evidence yet that there was a difference in the back plates from inception until 6/1972. However... I also only see one part number for the cover, and we know there were different versions of that from inception, but before the 73 models: So, perhaps there are differences in the back plates also (before the 73 models).

I picked back up on one of the seat backs on Sunday. First, I used some spray can adhesive to put this 1/8" grey foam sheet on the seat back: I used this plastic wrap around the seat back to aid with sliding the upholstery on: The I made another listing rod for the back upholstery. If you are needing to do this yourself, you will want the seat upholstery to be installed on the head rest like shown before you attach the listing rod to the wire on the seat frame (second pic). At this position, you can put on zip ties: Next, I installed about 6 hog rings, cut away the zip ties, and unfolded the rest of the material: As you can see by looking at the last picture above, the seat upholstery is "short". This is where it got interesting (read very difficult). As I yanked, tugged, pulled, massaged the upholstery from the head rest area downward, it fought back mightily. The foam seems to be a tad bid oversize to me. Anyway, I decided to put the seat back in the sun for a while and let it bake. I put the bottom seat cushion out there as well. After an hour, I gave the wrestling match another go (while I also was out in the sun). With what I'd call extreme effort, I was able to get the flap on the front of the seat back upholstery onto a couple of the hooks. But, it was super tight and quite a bit stretched. I brought it into the garage again to get out of the sun and again tried to convince the upholstery to find a lower position on the metal seat back. After getting the material on about 2/3rds of the hooks, I had to leave for a soccer game. That is all I have of pictures for now, but I will pick this back up again soon.

Interesting. Any idea what they are called?

On your first observation, know that the picture you are referencing was a picture supplied by @CanTechZ Something to point out is that I am unaware of differences in the back plates for the "earlier" cars. The parts book shows the same part number until June of 1972. I think it is the camera angles... and possibly that these back plates are relatively easy to "damage" by bending. The front of mine is (was) bent as can be seen if you look closely here (compare at two blue arrow locations: That said, I worked on the filter back plate a bit yesterday in my hydraulic press. I corrected what was obvious to me, but the filter doesn't really fit much better, maybe a little bit at the front. So, I don't know. I do know that the car came to me with two air filter housings. Out of the two back plates and covers, I selected the best ones and restored them. I don't seem to have to other pieces. I think I sold them with a batch of parts some time ago.

The seals inside are original. They are made of a type of rubber that I don't think ever compressed much. I am beginning to think that my problem is the back plate. I suspect that somehow it the outer edge has been bent back... If you envision it mounted to the carburetors, then I think the outer portion of the plate has been bent towards the engine. I took my back plate off the engine last night and set it on a work bench. I examined everything very carefully. At the front of the filter housing, the gap (to the cover) is a bit larger than at the rear. Though it is hard to see, upon close examination, I see that this circled area of my filter back plate is pushed in a bit. With this surface pushed in, the outer part of the housing moves away from the housing cover. I found this picture of a back plate on eBay - note the "plane" of this surface: And here is mine: While I think this is part of the issue, I am not sure it is all of the issue. At the back carburetor location on my filter housing back plate, I don't see evidence that it is bent like the front. And the filter cover doesn't contact the seal there either. I'd say the distance at the back is about 1/8". While at the front, the gap is about 1/4". I am going to try getting creative with my hydraulic press to attempt to address this. I have in mind putting the front air horn down face first, and then using some plates or boards to bridge across the backside of the plate, and then use the hydraulic pressure to push on the plate on the curled edges. Effectively, the area where the horn is should move "up" (horn will be face down in the press) and the back plate will move "down". I will try to protect the paint with soft rags placed in suitable locations. If anyone can do some examination (to see if bent) and measuring of their back plate (if not bent), that would be helpful.

AAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHH! Jeez! Sorry that happened Charles!

Today I set the car down on blocks under the tires to load its suspension so I could torque all of the suspension fasteners to factory specifications. Then I pulled the rocker cover to have a look at the cam and valve train. I was pleased to see that all looks good. Then I switched back to attempting to put on the seat upholstery. I worked with one seat bottom for quite a while. First, I made the decision to trim down the funky lip of foam at the front. I used as scroll saw to remove a portion of it from across the front of the seat cushion. Then I used some 36 grit sand paper to smooth out where I had cut it. I loosened the zip ties that are holding the upholstery to the seat frame. I still do not have any hog rings installed. Then I very carefully started working the upholstery onto the metal points/blades which are on the seat frame. I started at the front of the frame. I worked point by point from the front, around both sides. When I had the upholstery on all of the front and side points, I pulled on the cord that is inside the piping and this cinched the corners of the upholstery nicely. I tied this cord, (there is one each side) and tied them together. Then I installed a piece of wire in the piping of the back seat flap, and folded that flap onto the points which are on the back of the seat frame. I did not hammer the points down yet. So, I can still take the upholstery off and redo things. Finally, I pulled the zip ties so they are fully tight. Here is how it currently looks. I think it was the right call to trim the front of the seat cushion. I no longer have that odd bulge at the top front. But, pulling the zip ties all the way down, which I believe will be equivalent to when I install the hog rings, I still have the wrinkles in the top side panels. I don't care for them. I may experiment with adding some foam in this top side panel area. I started on one of the seat backs as well. From the factory, there were some vinyl pieces glued to the seat back on the edges: I checked location in my reference pics, and then made and glued some new ones in place. I believe the very thin sheet of foam that was on the backs of my seats was original. The new seat back upholstery from Distinctive Industries only has a pieced of reinforced vinyl for the back (of the seat back). So, I plan to install a thin layer (about 1/8") of the grey foam you see in the pic above to the metal seat back. And then install the upholstery over top of that. I have heard that it can be difficult to the install the upholstery on the seat back. I see that there was some very thin plastic originally as well. I may wrap the seat back (with 1/8" foam glued in place) in thin plastic also. I think the plastic will allow the upholstery to slide on easier.

Yes! I took a few more measurements today. Outer filter case is not quite 2 7/8" from front surface to curled lip. With the filter sitting inside the outer cover, laying against the seal, there is only about 5/16" left of "depth" to the edge of the curled lip on the back. Filter is against seal on the back plate. So, again, when the cover goes on, seals are seating on both sides of the filter element, and leaving about an 1/8" inch gap between the seal and the curled lip of the cover. Is this the correct back plate?

It's debatable if this raw video footage is more interesting than watching paint dry, but I was able to get the engine started and running for more than 1 min finally. The temp gauge was working its way well past normal, so I shut it down. I did grab my laser pointer and it was saying all was well - temp gauge was not. The needle was partly in the P like this: So, I decided to run it again and restart it to break in the cam at 2000 rpm for 20 min.