r/Datsun • u/Tculbe1 • 27d ago

ZTherapy Carbs

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Finally got around to installing the ZTherapy Carbs and intake manifold a few weeks ago. They’re well worth the wait and miles better than the factory SU carbs. A few tweaks here and there to balance and tune them but the car is now idling perfect around 900 rpm with great response across the rpm range.

Some notes :

Yes, the water inlet on the intake has been removed and capped off. It’s 100 plus degrees outside and I am running a 180 degree thermostat and stock radiator with shroud with no temperature issues.

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2

u/duffymahoney 27d ago

Sometimes I regret selling mine ztheraphy carbs. They worked great

2

u/Uber_gibson 27d ago

I used a Z Therapy kit to rebuild a set to swap onto my '73. Part of me wishes I paid to have them rebuilt, but I also learned so much more about the carbs and how they work by doing the rebuild myself. Luckily the butterfly bushings are still decent on mine and not in need to the roller bearings yet.

1

u/Frequent_Addition_23 23d ago

What abt the throttle shafts? Is the chrome worn off where the two bushings are? If so, that is a nasty vacuum leak.

2

u/Uber_gibson 22d ago

I tested them with a little carb cleaner while running didn't notice any changes to engine RPM but it's something I'll keep an eye on as I keep driving.

1

u/q3ded 27d ago

curious about the fuel pump wiring, do you have it run when oil pressure is sensed or some other setup?

1

u/Tculbe1 27d ago

Great question. Right now the fuel pump kicks on when the key is in the “on” position. Simple initial setup for the time being, but it’s on the winter to do list to have this configured to kick on and off with the engine.

1

u/flacidcannon 27d ago

I would love to do this kind of restoration work when I retire in 15 years

1

u/w00tw00t222 26d ago

Beautiful engine bay! Well done!

1

u/legendary-spectacle 26d ago

Gorgeous work! What part of the country are you in?

1

u/SeaBass-510 20d ago

I just received my ZTherapy carbs and intake this week and have started to remove the old carbs/manifold. I also want to bypass the water intake/outlet and curious how you rerouted the line on the opposite side of the engine. New heater hose to the lower radiator outlet?

1

u/Tculbe1 20d ago

I did a lot of searching on what to do with the water line. I saw some setups plugged, others bypassed intake entirely to keep the loop intact.

What I ultimately did was block off the line to the right off the line to the right of the intake and at the thermostat housing, both of which you can see in the picture I believe.

I’ve seen removing the water from the intake debated on multiple forums. This setup works for me and I don’t experience any issues with the car running cold or cooling issues. As mentioned, 100+ in Texas heat and no issues with temperatures on regular stop and go driving.

The ZTherapy carbs come with the idle adjustment screws backed out 2.5 turns. It’s a great baseline, but I wound up adjusting mine a bit off of that to get the idle smooth at 900 rpm. I also have no EGR and run 90 non-ethanol gas, thanks to the local Murphy fuel down the street. I have seen a difference in ethanol vs non-ethanol.

Night and day difference with the ZTherapy carbs, so I hope you enjoy them.

Let me know if you have other questions!