We're bringin' back the Flat Tops!

[Captain Obvious]

Jayhawk, That's a beautiful flat top pic. Is that yours some many years ago? I looked it over pretty closely, and the only fault I can find is the failed insulation on the throttle opener and EGR solenoids. That's the only little nit-picking issue I could come up with!    

1 hour ago, 240260280 said:

I thought it was the extra pollution stuff on the 73 manifold that caused the complexity and problems which painted the flat tops with the same brush.

I think it's a whole bunch of things. The extra pollution controls, the more complex throttle opener system, the more complex idle mixture adjustments, the power valve, the water running through the carb bodies. All the extra plumbing associated with all that stuff. A whole host of things.

Capped off by the fact that you can't compensate for faults elsewhere by adjusting the nozzle depth like you could on the round tops. You have to get things right... You can't just cover them up like you could with the round tops.

[jayhawk]

The pic is of a '73 that I saw in Portland OR a few years ago.  The owner had 3 1973 Zs all restored like that.  I don't plan on polishing/chrome the valve cover like that one.

I agree that the extra pollution controls and other complexity (plus the early vapor lock issues) were the real cause of the problems ascribed to the flat tops.  To me the complexity is a learning curve issue from the features of the flattops like the power circuit and idle adjustments that (in theory) allow the carbs to be tuned for both power and idle.  

I wonder if anyone has ever run a dyno test on a single Z using both the round tops and the flat tops.  With everything else as equal as possible and the carbs mounted on the same intake, with the same pollution equipment (if possible), etc.  Might be fun to do that and see what the differences are that are just due to the carbs.

 

[Captain Obvious]

Yeah, I'm not a fan of the polishing either, but I couldn't rightly flag that as a "flaw" since it's a style choice. Valve cover, oil fill cap, carb bodies, backfire valve polished...  I personally don't care for any of that.

I'd love to participate in that dyno test to compare round tops to flat tops, so if you hear of something like that brewing, let me know!   

It's not necessarily going to show anything though since the dyno test is just running full bore output at WOT. Under those conditions, you're not using many of the technological improvements of the flat tops and both sets of carbs should easily be able to be tuned to produce the same results. It's kind of a "static" test.

In theory, the flat tops should shine in other areas like idle cleanliness, mixture consistency under varying operating conditions, gas mileage, and transition power on pedal stab. None of that would show up on a dyno test.

[Patcon]

@Captain Obvious

You could include some O2 datalogging to pick up those qualities

[hls3073z]

On 7/2/2018 at 7:33 PM, jayhawk said:

Hi, I’m the “gentleman” (Rich may be a little too generous ?) that is the original owner of the ‘73 Z of this thread.  I’m happy I managed to hang on to my Z this long and yet ashamed I have let it sit so long.  I bought it new from Gubrud Valley Datsun in Mt Vernon Washington shortly after returning from an 11 month deployment with my US Navy A6 Intruder squadron aboard the USS Kitty Hawk.  ( which was a great way for a young ensign to save his pay to buy a Z!).

I’ll post more info about the history of this car when I get back home after the 4th.

 

Hello Jayhawk,

we are about  in  the same position except no one ever called me a "gentleman".  I've got a '73 I bought in '76.  I was lusting for one ever since the RT article in 70?  Anyway, I had to graduate with an EE degree and get a job before I could buy mine.  I kept mine garaged until 2000 when the garage got filled with inherited stuff which eventually got pitched.  Sadly my Z suffered for it with the rust.  It sat the last 3 years with a broken clutch  and the wife threatened to haul it off I didn't move it.  So I said no problem, decided to change the broken pressure plate, of course exhaust studs broke off, long story short.  The engine is now pulled out and I"m going to paint at least the engine bay so I can get it running again.  Its a sin for someone like me to abuse a perfectly good car like I did.  Good thing I'm retired.  btw, I've got round tops.

[Captain Obvious]

9 hours ago, Patcon said:

You could include some O2 datalogging to pick up those qualities

True, but the only thing most people would care about is peak HP. Maybe you could convince them that the power stab transition is important, but other than that?

[Patcon]

17 minutes ago, Captain Obvious said:

True, but the only thing most people would care about is peak HP. Maybe you could convince them that the power stab transition is important, but other than that?

Maybe, but an engine that runs closer to stoich requires a lot less maintenance and responds better to fuel inputs

[Captain Obvious]

Haha! Well if someone wants to set something up, I'd be happy to participate! Not sure I'm qualified, but I can twiddle some knobs and stuff!    

[hls3073z]

Looking at your photos I see what must be a universal problem regarding these restorations, that battery platform.  Mine is also rusty.  I can clean out the visible part but I am wondering what it looks like on the reverse side (the part you can't see)  of the battery platform and what to do about it.  Is the paint ok there if the rust did not eat thru?  Do you clean that reverse surface and repaint it?  fwiw, mine is simply rusty no holes thru it.  So I'm not sure what to do about it.

[Patcon]

39 minutes ago, hls3073z said:

Looking at your photos I see what must be a universal problem regarding these restorations, that battery platform.  Mine is also rusty.  I can clean out the visible part but I am wondering what it looks like on the reverse side (the part you can't see)  of the battery platform and what to do about it.  Is the paint ok there if the rust did not eat thru?  Do you clean that reverse surface and repaint it?  fwiw, mine is simply rusty no holes thru it.  So I'm not sure what to do about it.

It is very difficult to deal with the underside of the battery tray and an OEM type replacement panel is unavailable. I believe the factory assembled the car and sprayed it the same way we try to do it today. After having done this, I can tell you it is almost impossible to get paint up in there. Even treating the underside of the tray is difficult

[CHL240Z]

@motorman7 great to see that you are taking on another restoration.  Looks like this one will take my spot at the shop soon.

 

Clay

[motorman7]

Got a lot of stuff removed last Thursday and today.  Got the Fuel tank, fuel pump, hoses, diff, half-shafts, trans tunnel fuel and brake lines, seats and steering column removed, among other things.  Took some good pics of the fuel pump since that is unique to the '73 (as opposed to the '70-72).  Also took some good pics of the steering column wires because, as we know, the green wire connects to the white wire.  Now  I just have to remove the dash, front and rear glass and interior vinyl and that will be it for the part removal.  I will clean things up and get most of the grease and dirt off before I  transport the body to Miguel.  I am hoping I can get this to the paint shop this Thursday.  The underside was pretty dirty with caked oil, so that may take a bit of time.  

It's interesting to follow all the Flat Top 'banter'.  It will make the final results all the more exciting once it is complete.

@CHL240Z, Yes,  I am keeping Miguel busy.  My white Z is down there already.  Now it will have company.