Datsun Roadster Forum-311s.org

Now that I have my 67.5 1600 in my new garage with such amenities as heat and light,



I can start on a critical assessment of what needs to be fixed. Wiring is a mess, and I have made a nice big laminated copy of the 67.5 SPL wiring diagram (tip of the hat to Jim Bain for his excellent colour .pdf)

Starting with the obvious, I'm fixing some interesting things such as fuel line routing, extra springs on the carb throttle linkages, a curious bridging hose between the two intake chambers and various other bits.

Here's the manifold before I did anything:



A few questions come to mind... first, is this the correct 67.5 intake manifold? Here are my observations:



1) It is a 4 bolt flange, the carbs are 2 bolt. Is this correct?

2) there is a capped off vacuum port attached to a piece bolted to the front of the manifold... where should this run to... the dizzy vacuum advance? There is a capped off port on the distrubutor as well.

3) a second vacuum port capped off with a piece of hose and a screw just behind the throttle linkage stop. It has a hex fitting and was threaded into the manifold. It's 1/8" NPT fine gauge threads that the manifold plugs I got from Ross @ Sports Imports fit perfectly into. Which leads me to number...

4) Removed the bridging hose, there were two threaded nipples that I removed. They are 1/4" coarse NPT, much larger than any plug I've seen in a roadster manifold. As mentioned above, the plugs I was sent from Ross were too small to plug these ports, but fit perfectly into the hole behind the throttle stop.

Here is how it is currently with some clean up & new parts:



Close up of the plugs, small one behind the throttle stop and onle of the larger ones:



So, as I've not seen a lot of 67.5 manifolds (that is, this is my first one) are these correct for this manifold? Here is the pic I use for reference (Michael Spreadbury took this of a 66):



Very different setup.

So the answer to my #1 question is yes, they are a 4 bolt setup. However, there are no vacuum ports anywhere and the two plugs on top of each intake chamber are the smaller 1/8" plugs from the look of it.

There is no flange on the carb side for the cylindrical piece with the vacuum port in #2 above. Not sure what that add-on piece is.

This is the correct manifold for the 67.5?

Thanks,

That looks to be a '70 manifold due to the Emission control mounts.

The vacuum advance nipple is usually underneath the rear carb body: -


It has to be a PORTED connection not a simple manifold connection to the distributor vacuum advance motor.

Those look like a 70 carb setup . They have extra ports to plug up plus that extra piece in the middle I removed. I have a set I used for awhile but wenrt back to my other earlier set of carbs.
I don’t really like the fuel hose right over the hot manifold. Not sure if that was stock or not.
Linda

The fuel line routing is original but as you mentioned, not very clever.
In our hot Summer climate that gave me a lot of trouble with fuel vapour lock.
Wrapped them all with Thermotec insulation and problem gone

Thanks for the replies...

Ross called and told me its a 1970 emission manifold. He has several of the correct 67.5 available.

And to Linda, yes, I agree the fuel line routing over the manifold is a bad design, I will be rerouting it away from the manifold as part of my clean up repairs. Nice tip on the insulating wrap, Nissanman... we don't get consistently hot here in the summer in Canuckistan but we have our share of 30+ deg C days.

The early 80's Porsche 944s had a similar fuel routing issue over the exhaust manifold and there were several engine fires. I was running at Spokane Raceway and a guy had to pull in... this was after they got the fire out, he was lucky:

Yeiks hot fire

Running a prone-to-deteriorate-and-split rubber hose filled with an explosive fluid past the spinning stuff in front and over the hottest part on the side, never seemed like a good plan to me.

68DSU wrote: ↑Tue Jan 22, 2019 11:38 am Running a prone-to-deteriorate-and-split rubber hose filled with an explosive fluid past the spinning stuff in front and over the hottest part on the side, never seemed like a good plan to me.

That's why you never got that job at American Motors or the Ford Pinto design team!

I usually buy the fuel injection rated line now, a little thicker and rated for Ethynol.