Is it worth replacing old hitachi SU carbs with remanufactured ones?

[jalexquijano]

I am having some kind of stalling problems with my 1972 240z. As mentioned before my car has a Far 311 Race Cam with 2 stock rebuilt SU Hitachi carbs

The car tends to stall on intersections and traffic lights. Due to the race cam the mechanic increased the RPM to 1100 but sometimes in such situations it lowers to 700 rpm. Should i consider replacing my carbs with these remanufactured ones?

Datsun 240Z Carbs Rebuilt Polished Twin Round Top Su Carburetors | eBay

Any honest opinions? This carbs are not cheap!!

[John Coffey]

Why don't you just tune the carbs you have?

[240260280z]

I agree. There is enough info on this site to tune them as well as how to inspect to ensure they are working properly and not binding.

SU's are fairly simple.... a throttle valve (like on any car) and a fuel metering part (a needle and a hole)

The key points are:

0. Fuel pressure is ~ 3.5 to 4psi

1. Mechanical linkage from pedal to throttle valves works smoothly

2. Each carb's throtle valve rests on its stop screw at idle

3. Air flow at idle is balanced by adjusting stop screws

4. Pistons move up and down easily and carbs are clean

5. Needles protrude equally from each piston.

6. Chokes move freely and jets don't bind when they move up and down (you can probably disconnect choke cables in Panama

7. No air leaks in intake plenum

8. Jets are ~ 2.5 turns down and holes are not ovaled

9. Needles are the same, are straight and are not worn

10. Air flows the same into each carb at 3000 rpm

11. Front 3 plugs look the same (front carb output check)

12. Back 3 plugs look the same (back carb output check)

13. All 6 plugs look the same (engine balance)

14. The car runs equally as poor when you lift the front carb piston (running on back carb) as when you lift the rear carb piston (running on front carb)

15. Fuel bowl levels are the same and ~19mm down from rim.

Ensure timing, valves, gaskets are in good form. I wish I could have met you when I was in Panama in Dec. it would have been fun to tune your car.

Edited May 13, 2014 by Blue

[PastorMike]

My opinion: Do not purchase the carbs

listed on eBay; too much risk. The seller

listed as remanufactured, however, the

description says rebuilt. Big difference!

Invest in some truly remanufactured carbs

from Z-Therapy and you will have a great

working pair.

[ajmcforester]

I like to work with the problem I have and not get new ones. Just clean them up and tune them.