Starting Carb Conversion: Flat Tops to Paltechs

[Dadsun]

I bought this Z (1973 240z, white/red, build date 10/1972) in April from the original owner, and have been working on restoring. (Will post some interior pics soon, hopefully.)  As some of you know, like @Captain Obvious and others, the original flat tops were neglected and this car has been driven about 5K at most, in the last 20+ years.

So, after some input from the board, and looking around, I settled on the Paltech round top SU carbs.  They are beautiful.  In fact, I'll have to clean/polish/replace the rest of the engine compartment elements to keep them from looking crappy by comparison.

I an not a mechanic, but consider myself handy.  I need some help on where to start.  See pics.

Q1:  I know where several of these Paltech hookups map to on my ''73, but not all of them.

Q2: I'm assuming the whole EGR crap can go away now - i.e., the wiring, coming from the distributor to the EGR mechanisms. Any tricks/concerns in the process?

Q3: I've read on the forum that certain '72 models have water ports on the mounting between the carbs and the manifold. I have not taken mine off yet, but I'm assuming it will be obvious.

Q4: Any other gotches, must-do's, don't forgets greatly appreciated!

 

[SteveJ]

1&6 fuel in

2&7 float vents to air cleaner

3&5 coolant lines

4 vacuum line to brake booster

8 positive crankcase ventilation

Edited October 24, 2020 by SteveJ
fixed a goof

[Captain Obvious]

Wow. Shiny.

Yes, all the EGR stuff can go away. Not that it matters to the discussion, but the control for the EGR doesn't actually come from the distributor. It comes from a relay mounted to the front right engine compartment, under the coil (I think). But whatever.  Haha!

You don't currently have any water passages between the carbs and the manifolds. And you still won't after you put the new stuff on. They're four screw round tops and there are no water passages through the carb faces.

I'm sure there will be some small gotchas along the way, but let's deal with them as they come up.

[Dadsun]

Thanks, guys. I believe, as an aside, I could also do away with the ugly heat wrap on the fuel rail now that I'm going to the round tops with the heat shield, carb/manifold spacers blocks, etc?

I've seen posts about going to piano wire for the choke cables, but for now I'm going to keep these and keep applying cable lubricant. Seems to be helping. 

Edited October 25, 2020 by Dadsun

[Captain Obvious]

Forgot. Your mention of the choke cables reminds me...

Unless they are loose in the box somewhere, you don't have the clamps that fasten the ends of the choke cables on the round tops. The flat top clamps are different and won't transfer over.

Edit - Found a pic. They look like this:

Edited October 25, 2020 by Captain Obvious

[Patcon]

That why heat wrap is asbestos!!

Proceed with caution...

[DatsunZGuy]

Maybe it's the angle or the gasket...but the carburetor spacer look like it's sagging a little in the middle.  Hopefully it isn't cracked.

 

[Captain Obvious]

I've seen many spacers with that sag. Probably just a shrinkage phenomenon from the molding process.

[CanTechZ]

That sag is on all four sides of four screw carb isolators.  I believe it was intentional as the sag looks the same on all four. Three screw carb isolators are flat on three sides and a different shape on the bottom for the water passage.

[jfa.series1]

13 hours ago, Dadsun said:

Thanks, guys. I believe, as an aside, I could also do away with the ugly heat wrap on the fuel rail now that I'm going to the round tops with the heat shield, carb/manifold spacers blocks, etc?

First, let me comment that those carbs and manifolds are true automotive jewelry - absolutely stunning!

Your mention of the fuel rail caught my attention so here are a few observations. The supply nozzle positions for the flat-tops are substantially different than for round-tops so I recommend you get a fuel rail from a '70-72 model car - the pic is a Series 2 style from the later '71's and 72's. The rail is longer and correctly positions the nozzles for the feed to the floats. As @Patcon mentioned, the asbestos wrap is a big caution. They put it on the '72's and later, carbed and injected. It has an adhesive that will have melted around everything, expect to find significant corrosion under it. Also, the wrap contributes to deterioration of the nylon insulators for the mounting tangs. I've restored quite a few of these rails and faced all of these issues.

Jim

[jfa.series1]

Restored '73 flat-top rail for comparison.

[Dadsun]

I'd like to move to a round top fuel rail at some point. Sounds like it's not on the critical path at the moment, but would be ideal.  I've already taken off my flat top rails once and re-wrapped them with new heat shield foil wrap when I was restoring the gas tank and cleaning all of the fuel lines.  I didn't realize the old dilapidated wrap was asbestos. Ugh.

I've texted the Paltech guy to see if he has choke cable brackets.  They were not in the box. 😞