Leaderboard

Not on the S30-series Z's firewall. 'Dot Engraving' displaces metal rather than removing it. In the case of the letters and numbers we are discussing, the dots are so close together that in close-up they look like one continuous form. The deformation is visible in the reverse side of the panel. The firewall sheetmetal on the S30 is thin enough gauge that some deformation of the surrounding metal occurs (noticeably more on some letters and numbers than on others) so it is all too easy to imagine this is the result of physical - 'one blow' - stamping. It isn't. Here's a bare metal example of a Nissan S30's firewall '3' number, showing front and rear. This is classic close-form Dot Engraving:

The process involved aligning a fixture to the firewall of the unpainted bodyshell (other Nissan vehicles had the identity elsewhere - for example my KPGC10 Skyline GT-R has it on the LH door sill) into which the full combination of chassis prefix and body serial number was dialled-in by the operator, and then the machine did its thing. We have seen examples of mistakes (operator error...) which have been 'corrected' by the same process and then authenticated with a Nissan 'hamburger' cipher. We can play terminology tennis between 'stamping' and 'engraving' to our heart's content but the process used was - I believe - more correctly described as 'Dot Engraving', where a punching point deformed the metal into the desired letters and numbers in the distinctive Nissan font of the period. This method - although in a much more developed and computer-controlled form - is still in use today. Here's a modern version of the machine (on the dreaded Ali Express, no less...) with a playable video: https://www.aliexpress.com/item/1005007340921417.html?dp=CjwKCAjwp_LDBhBCEiwAK7FnkgNg_pgoKEwp2vl_LmTjbAZXtPHK3lxpnCZE8Rsz8cmrvpF30NaRhxoCKVwQAvD_BwE@254613&isdl=y&aff_fsk=_okqVOWy&src=delupeUK2025&aff_platform=aff_feeds&aff_short_key=_okqVOWy&pdp_npi=4%40dis%21GBP%21616.83%21585.99%21%21%21%21%21%40%2112000040338251243%21afff%21%21%21&cn=254613&cv=466926&af= I would imagine that the somewhat laconic and haphazard nature of the late 60s Nissan Shatai results was symptomatic of the machinery being used. I wouldn't rule out the possibility that it was - along with Nissan's distinctive font - intentionally difficult to tamper with/replicate/forge. Anyway, the big point here is that when people talk about 'firewall stamping' and 'VIN stamping' it calls to mind old-fashioned letter and number stamps that would be whacked with a hammer to make their mark. Doing that on an unsupported firewall (the other side is in the cowl well...) would be pretty difficult without big deformation, and if supported it would require some other kind of fixture on the other side. In my KPGC10'S case it would be impossible on the (blind) door sill. I'd like to see a machine that could physically 'stamp' a firewall VIN on an S30 in one go (I'm imagining it to be steam-powered...) but the whole thing sounds far too impractical. The dot engraving machine seems to have been a lasting solution. This is actually a subject which we have discussed previously here on the forum. @kats even came up with a photo of the same fixture still being used on late 1980s and early 1990s Nissan Silvias (S13/S14?) but - of course - I'll be damned if I can find the thread and the image. Don't know why this place is so hard to search for something I know is here. S30 chief engineer Hitoshi Uemura gave me a copy of a period Nissan document which showed the positioning instructions for the chassis number fixture, but I was asked not to publish it (and I'll honour his request).

What’s the matter with Cliff??😂

is killing me.

I'm having corective surgery. 2.4 to 2.8 stroker🤣

Did you happen to check for voltage on the black/white wire on the ballast resistor with the key in ON? What is the resistance between the engine block and battery negative? If you run the hot wire to the coil, measure voltage to ground on coil to negative while someone else is cranking the engine. You should see it at 12VDC+ and periodically drop when the ignition system connects it to ground. Also I can't remember, are you using points or an electronic ignition?

Exactly that. The engraving fixture hooked onto the firewall in a fixed position (one for RHD, one for LHD) and the operator did his stuff. 99.999% of the time he got it right. The rest of the time stuff like this happened:

Incidentally, you might be interested to hear that the Japanese market FSMs use the term 打刻 ('Dakoku') in relation to the individual vehicle ID on the firewall. It translates as 'Stamping' in English. They use the same term for the engine number and the engine bay tag, when they are clearly performed with different processes to that on the firewall. Again, I would not take it literally. It is similar to saying that something is 'written' on a page when it is printed, and vice-versa.

I got curious so I looked in the GI pages of the FSM's. 1972 seems to be the first time they describe the stamping of the identification number on the firewall (cowl). 1970 and 71 don't mention it, that I can find. 1970

Be patient. Good advice. Too busy yesterday but got back to it this morning. BTW I did get the pics from Harbor Freight. They worked great. Kept working them gently around where the filler hose meets the gas tank using WD 40 with it's straw for a lubricant. As soon as I let the tank down a bit further and pushed it to the side it popped loose from the filler hose. Now lets see, reassembly is just reversing what you did to take it apart, right? Great video on tank cleaning by the way. Lol. Thanks for all the help and suggestions everyone. I'll probably start a new thread soon on my reassembly efforts with the new gas tank.

@siteunseen Thanks Cliff. I didn't see it in those search results. Part of the problem is figuring out what the OP called that chrome squeegee strip... On another note. I'm all legal now! :)

So I don't know that I've made any progress yet this weekend. I went to test fire the car. It will crank but acts like it has no spark. I checked voltage at the coil in the run position and it doesn't have any voltage there. I ran a jumper wire from the battery to the hot terminal of the coil and when she turned the key on you could here what sounded like the starter solenoid getting pulled in. I still couldn't get it to fire up. The only upside is it is pumping fuel from the tank. Although a portion is all over the shop floor now... oh and I do have headlights until the one burned out but no high beam indicator Super frustrating