inline6

Attention grabbing for me for my restoration. Some number of fasteners is missing - I need to find and add. I will clean it up a bit as I progress on it. 🙂

I have been working on documenting the fasteners on the car. When I finish all of the documentation of the hardware, I will upload a worksheet to the resources section. In the meantime, anyone with a google account can access what I have so far by going to the link: Datsun 240z hardware - 6/1971

I see it has been a long time since I posted an update. I am still working on fasteners. I suspect that I am putting too much time into them, but I have no experience with getting hardware replated. So, I feel I can't leave it up to chance. I will probably send some "test" hardware along with it in various stages of prep or lack thereof. It will be interesting to see how the test hardware compares to my fully prepped hardware. I have a few observations to share, but not much of an update. First, the u bolt that holds the steering rack from twisting on the front crossmember - I happen to have two. There is a white blot of paint from the factory. I noted that under the white blot, the part was silver. So, this part seems to have received zinc plating (clear) from the factory. The clips that secure a rubber weather strip to the unibody under the top of the fender, here in their as removed condition. Amazing that they don't even have rust on their entire surface: The battery inspection panels have these metal clips. I find it interesting that they received a black coating originally that is not paint. This is actually consistent with other black plated parts I have found on the car. Black parts are, nearly without exception, springs or springy. The bushing in the bracket that bolts to the engine compartment firewall, which supports the back of the main throttle rod, is always rotten on any 240z. It is a two piece bushing, with a plastic inner barrel and a rubber outer grommet. The rubber part broke when I pried it out of the bracket. Here it is temporarily put back together: First pic has half of grommet removed. Middle pic is of the plastic barrel by itself. I will be trying to source a similar bushing from McMaster Carr. And lastly for today, I find it interesting that the hatch hinges were bolted into the car when it was painted at the factory. The odd part about that is that the rubber enclosure was in place also. My car had shims on the right side hinge only, and you can see by the original paint that they were in place when the car was painted. This, and the fact that the taper head bolts that hold the hatch to the hinges were not originally painted, tells me that the hinges and hatch were bolted to the car for fitment, and then the hatch was removed (the four taper head screws only were removed) for the original paint application at the factory. Also, hinge assemblies and shims were clear zinc, and backing plates were yellow chromate/cad. I think I am nearing the end of the great fastener round up and restoration of 2020/2021. I ordered some new ones a couple of days ago to fill in for the small number of originals that went missing at some point. I am digging through my boxes of old Datsun hardware to find suitable replacements also. I am having some success there, finding matching hardware with 4's and 7's and 9's on the heads of bolts - proper style and length. Yeah... I am more than a bit OCD I think.

Thanks for that. I see differences in the brackets. I will work on mine more and make it look like that one.

Different somewhat, probably because it is a series 1 car, but this one looks really good (and likely original) to me compared to many I see on previous BAT (Bring a Trailer) cars. https://bringatrailer.com/listing/1970-datsun-240z-65/ (around pics 62-67)

I added clay to replace the material that was removed from the bores for eye-browing the block. I then put the head gasket on, lightly bolted the head on, and ran the engine through revolutions to check for valve interference. When I took the head off, there was none that I could perceive - there were no marks in the clay. Of course, this engine is bored over a bit, so there was that chance before mocking it all up that they would not hit. 🙂 After checking that, I pulled all of the clay off and combined it into one piece which measured out to less than 1 cubic centimeter. So, compression ratio is not significantly reduced. Some pics - Cylinders 1-6 in order: Additionally, my fuel line assembly was pretty bent up, so I put it on the engine in a mock up fashion and worked on straightening it for an hour or more with a crow bar, vice grips (with wood stirring sticks used for protection from marks), and a hammer. It looks ok now, but I wonder about the brackets, if they are near original in appearance, or if they are quite bent still. The parallel aspect of the two lines seems pretty good to me. The brackets dictate the height of the lines along their lengths without much variance. I want to be sure the shape of the lines in the assembly is all sorted out before I send it off for re-plating.

I am getting close to satisfied with the block eye brow and combustion chamber mods. I have a few areas I see in the pics that need attention. I actually can see them better in the pics because I can zoom in on them and compare from one cylinder to another. So this is helpful to document them in this way. Cylinder 1-3 and 4-6: Cyl. 1 exhaust (front of bore - also note ring location by rust stain), Cyl. 2 exhaust (back of bore), Cyl. 3 exhaust (back of bore): Cyl. 4 exhaust (front of bore), Cyl. 5 exhaust (front of bore), Cyl. 6 exhaust (back of bore: Cyl. 1 intake (back of bore - also note ring location by rust stain), Cyl. 2 intake (front of bore), Cyl. 3 intake (front of bore): Cyl. 4 intake (back of bore), Cyl. 5 intake (back of bore), Cyl. 6 intake (front of bore): I think I have those all labeled correctly. Of course, I also still need to assemble everything in mock fashion to check clearances.

I created a spreadsheet many years ago that is nice for exploring transmission options. Here are a couple of screenshots: In the rows below the screenshot above, I have the speeds in gears return in formulas for each 1000 rpm This sheet is nice because it accurately (I think) takes into consideration the tire size as well as the rear ratio and the gears. You only change a few parameters... and, it allows you to plot speeds in gears and look at a graphical representation: I used it recently to investigate using a 240SX transmission. If you want to use it, I can upload it somewhere for you. Let me know.

Chambers 1 to 6 in order from left to right after very little ground away, only nearest the valve and to the fire ring: I put the entire head inside a plastic bag and taped off everything so I didn't get any grinding dust anywhere in the head or valves, etc. I will check valve to block clearances next. Before the head goes back on for good, I will address any sharp edges that remain.

Thanks for your comments! Yeah, is hard to explain. Basically, if you look at each of the pics of chambers 1 through 6, and look at the 3 o'clock and 9 o'clock positions specifically for each, only chambers 1 and 2 have edges that match up with the fire rings... and further, for the #1 chamber, it is only the exhaust valve side that matches up (3 o'clock position in the pic), and for the #2 chamber, only the intake valve side matches up (also the 3 o'clock position in the pic). All of the other combustion chamber edges (at 9 o'clock for all chambers, and at 3 o'clock for chambers 3 through 6) are not yet cut as far as the edge of the fire ring. So, I am saying it seems like I need to open the chambers at those positions for each chamber so that they all align with the edge of the fire rings in the gasket. Understood. I have to provide clearance for the valves, so trying to do that, and I am assuming that breathing benefits that come from what I have outlined will be worth more than compression lost from the mods. I have no idea though - so if there is an expert who chimes in, that will be great! Yep, it is oval. It is wider at 3 and 9. And I'm not touching anything at 6 and 12... or 5 and 11, or 7 and 1 for that matter. I probably went a bit far north and south with the eye brows I already cut in the block at the 3 and 9 positions. The rest of my mods to the block will be more central to the 3 and 9 positions, generally. Agreed. And yes, the gasket has been compressed once. But I will leave a small amount of material there so I am not precisely at the fire ring with the edges of the chamber. The two edges mentioned above that are already matching up are REALLY close.

Thanks. I appreciate the positive reinforcement! I have been studying it and the cylinder head for a few minutes each of the past couple of days. I want my next steps to be right ones. Checking the gasket against work that has been done so far on the head (valves are marked with cylinder number): The work already done to open up the breathing on the exhaust for #1 and intake for #2 puts the edge of the combustion chamber at the gasket edge, but only for these two edges: It seems desirable to do further work on the other sides of each of these chambers to align the chamber edge to the fire ring also... and to do the same for the areas where the chamber wall is close to the valve heads in the other chambers as well. That said, the tops of the bores are not as wide as the chambers in the matching areas, even after eye-browing. So, the question is should I open them outwards to match? And, should this be done for both the intake and exhaust valve sides of the cylinders (safely above the number 1 piston rings of course)?

Alright then. I took the head off today. The head gasket didn't stick to the block or the head, so I think it is reusable. After I got the head off, I went to work on modifying the gasket. I used a washer with a 1/4" hole to guide the drill bit. With the gasket modified, I turned my efforts on eye-browing the block. Hopefully, I have not royally screwed up here. I removed the timing chain, rotated the crank to get the pistons below deck, and then covered the block with a plastic bag, and cut out the top of it so I could access the tops of the bores. piston 1 - pic taken from passenger side - front of piston is toward the top of the pic: piston 2 - pic taken from passenger side - front of piston is toward the top of the pic:: piston 3 - pic taken from passenger side - front of piston is toward the top of the pic: piston 4 - pic taken from passenger side - front of piston is toward the top of the pic: piston 5 - pic taken from passenger side - front of piston is toward the top of the pic: piston 6 - pic taken from passenger side - front of piston is toward the top of the pic: piston 1 - pic taken from driver side - back of piston is toward the top of the pic: piston 2 - pic taken from driver side - back of piston is toward the top of the pic: piston 3 - pic taken from driver side - back of piston is toward the top of the pic: piston 4 - pic taken from driver side - back of piston is toward the top of the pic: piston 5 - pic taken from driver side - back of piston is toward the top of the pic: piston 6 - pic taken from driver side - back of piston is toward the top of the pic: A few more pics: I did this with a die grinder and oval cutter. Tape and bag is still in place. I think I will switch over to a tapered roll and try to look for inconsistencies to address... as well as smooth the eye brows to final finish. I am well above the top ring land currently, and inside the fire ring on the head gasket as well. I was being cautious (I hope!). I will check clearances and continue - before I bolt the head on.

A comparison of RPMs and speeds in gears between the US spec 4 speed, 3.36 and stock tire size vs. a 240SX 5 speed, 4.11 and 196/55-16 which will go on my car. This tire size is a bit small perhaps. But, I made a slight miscalculation before I bought them, and I am trying to keep the tire from rubbing at all on my stock sheet metal (and the car will have aftermarket springs which will lower it also). Besides the high RPM of the 4 speed for interstate travel, another thing I do not like about the 4 speed is the gap between 2nd and 3rd. Performance is decent in first and second, but then a noticeable lull when then shifted to third.

Well, thanks @Racer X for getting me to look at this closer. I continued looking at pics and reading through some old posts and I see a problem that I did not before. Coolant holes in the gasket are not to my liking. My head gasket: My block and head: A Nissan Comp MLS gasket: So, at this point, I don't feel good at all about the gasket I used. I should have checked the coolant holes. It seems best to pull my cyl. head off at this point. I still have the issue of pistons above the deck by .025" and all the thoughts shared earlier in that regard. So, will have to see about how best to proceed. First step is to take the head off.

Hmmmmmm. I chose not to do that for this engine. Prompted by your question, I did some researching of eyebrow notching the L24. I found that some people's L24's had valve to block contact. I became a bit concerned that I missed a required modification to keep the larger exhaust valve (or the intake) from hitting. I found a couple of relevant threads: It looks like I should have checked mine out specifically for clearance issues. The head has been bolted and torqued with a new Nissan gasket at this point. I don't know if it can come back apart without replacing the gasket. Kind of a pain... So, my block is bored .030" over which is more than the .5mm Carl mentions. From a valve clearance standpoint, I am probably ok. That said (and I will attempt to verify as best I can without removing the head), is it highly beneficial to do?

😖 UNACCEPTABLE Rebel!

Hahahahaha! Oh man, there are better things to do than that for sure! Welp, it seems with our little sample of three, that there were... "variations" 😜 In case anyone cares, here is what Nissan has in stock - the part number changed again by the way:

That is a job very well done. Couple of questions if you don't mind? What is the 24271-2P010? Does that part number correspond to the dark piece of thin foam? Did you reuse the original vinyl on the flap door? The hardware... is original and re-plated? Did you lose any when you had them re-plated? I am concerned about losing smaller stuff like those sheet metal screws when I send mine off to get re-plated. When I took my heater core assembly apart, I saw evidence of some foam which was originally glued to the sides of the heater core. It was only about half as tall as my replacements in these pics, but you might want to add that to block off the air gap between the core and the sides of the box, if you didn't already do that.

Can anyone confirm that these are the correct valve cover bolts for a 1971 240z? The ones that came with my car were not original. These came from a slightly later engine - I believe they are from a N42 block/N42 head L-28 (which is probably from 1975 or 1976).

Dude... Have you ever done a roof replacement on a car fitted with a sunroof? That is a lot of time and effort. Four speed vs. 5 speed does pale in comparison to that, for sure. Regarding rust... I am so glad to be restoring an original AZ car that then sat in a Colorado garage for 28 years as my starting point. I couldn't agree more regarding 2, 3, 4, 6, 7, 9, and 11.

Too funny - hahahaha! I just don't want to rebuild my 4 speed transmission. Seems like a waste of time and money to me. I have decided to put a 240sx 5 speed transmission and 4.11 Quaife lsd diff in the car for now. I will keep the original 4 speed and differential stored out of the way on a shelf in the garage. 🙂

I have the original driveshaft from my 6/1971 car. A quick search seems to indicate that the diff didn't get moved back until the 1972 model year cars. I'd have to look at my suspension pieces to confirm that the change wasn't made yet in the production.

My memory fails me I think. I recall getting a custom driveshaft made for my 12/70 car to get the 83 280ZX box to work with the rear end after correcting for driveshaft angularity by moving the diff back more in the car. Was a custom driveshaft not necessary? Is it not necessary for the same transmission added to later 240z's? I am also about to put a 240SX 5 speed in the car I am restoring. I'm not sure if a custom driveshaft is necessary for that application, but will determine soon enough. I realize that is a different 5 speed entirely and not part of the point I was attempting to make. Thanks for your comment.

The English differential carrier for my Japanese car has arrived! The 4.11 differential has been dis-assembled: My plan at the moment is to strip, prime, and paint all of the gloss black enamel parts of the car that haven't yet been painted... in one day! That will require suitable planning and space. I am thinking I will wait until I am 100% done with the car body work and have carted it off to the paint shop. That will free up a lot of room in the garage. The list of items is extensive: front crossmember front control arms front compression rods front strut housings front strut springs (both stock and aftermarket) front strut upper spring seat front strut upper mounts front ball joints anti-roll bar anti-roll bar mounting reinforcement plates anti-roll bar mounting brackets steering knuckles steering arms outer (already painted) steering rack housing steering rack mounting brackets steering rack u-bolt brace steering shaft with u-joint front wheel hubs front differential crossmember - diff and front suspension mount differential limiting strap brackets differential rubber isolator mount - front differential rear mount - mustache bar differential rear mount - mustache bar washers with bonded rubber differential case differential front flange to driveshaft driveshaft (already painted) rear suspension crossmember - rear suspension mount rear suspension vertical supports rear suspension brackets - control arms to vertical supports rear suspension control arms rear axle shafts rear axle shaft - inner flange to differential rear axle shaft - outer flange to axle/hub rear wheel hubs rear brake backing plates rear strut housings rear strut springs (both stock and aftermarket) rear strut upper spring seat rear strut upper mounts engine oil pan engine mounting brackets engine mounting isolators transmission mount transmission mounting isolator clutch slave cylinder handbrake handle assembly (partial) radiator gas tank driveshaft (already painted) seat frames lower seat backs upper pedal box (already painted) clutch pedal (already painted) brake pedal (already painted) gas pedal brake booster one way valve mounting bracket brake booster mud guards inside front fenders hood tension rods front tow hooks rear tow hooks battery upper frame Then again, maybe I will do a couple of batches - it might be easier in the long run!

I went on another quest to find hardware that I have not run through the prep process yet and it led me to my seats. The seats had been recovered at one point, but thankfully, whoever did that work didn't disturb much of the original construction. So, I was able to take pics and document how things were done at the factory, which I hope to replicate accurately. Some disassembly pics: A piece of material was glued in place over top of the straps. I found that interesting as the material is just a canvas type cloth was not inherently flexible. So, I don't think there was much give in it compared to the straps which were elastic. The "U" shaped wires that hold the straps to the frame were some of the hardware I was after for re-plating. The "elastic" straps were stretched and hard as concrete. This should be considered a mandatory replacement item for "original" 240z's with this type of seat construction for sure. Bare metal in the seat frame that hasn't even surface rusted. Original foam application from the factory included a thin sheet glued to the back of the seat with edges wrapped around head rest foam and then covered by a super thin clear "bag" of plastic I disassembled both seats, and collected the hardware I needed to get plated. Both of my seat back adjustment knobs are cracked, so I will look for some that are not. The design is not very good on those - they are not very sturdy. It would be nice if there were some one piece billet ones available, but that is not likely to happen. I saved all of the seat foam - in case. I plan on buying new foam which is available from online sources. I have black seat upholstery that was made by Distinctive Industries, and understand that I have to pair that up with the correct foam version (there are a couple of options available currently) for proper fit. For now, the hardware from the seats will be cataloged and bead blasted, tumbled, etc. I am running out of hardware to track down... I think! I am looking forward to moving on from the hardware stage of the restoration.