Stock A12 fuel pump has enough capacity (flow) to supply up to about twice the stock HP, and to supply two carburetors or more

For twin Mikuni 40s on a stock engine (A12, A14 or A15), this jetting works well:
* NOTE: jetting depends on venturi size
With 32mm venturis: 128 main jets and 180 air jets
With 29mm venturis: 116 main jets 165 air jets

Anybody has jeting table, a program or yours car jeting?

hI!

I thought the stock fuel pump doesnt have the capacity to fEED fuel to twin 40 solex Type t carbs

First i need find the problem - lack oil of on rocker arms and i will follow your advices
I read this on the forum

Distinguishing Features
Any A-series cylinder head can be bolted onto any A-series engine block. However, compression ratio, port size (oval port, and round port), and manifold stud pattern need to be taken into consideration. Naturally, it is best to match port type, and size (e.g round port manifold, and round port cylinder head).
The most critical difference, is the rocker shaft oil passage. It was relocated in 1974, as part of the A-series engine redesign.

The rocker arms are interchangeble before and after 1974???
Or i set up an incorrect A12 Cylinder Head Gasket i will buy now this one

http://www.ebay.com/itm/NEW-GENUINE-C ... :uJcAAOSwIQdZMKFU&vxp=mtr


Secondi have another thing which makes me worries The carbs that i bought originally had Mainjet 160 airjet 210 and i changed them to Mainjet 120 and airjet 190
The car start well keeps a good idle, the engine has a good reponse to the acelarator but on street looses power on some rpm ranges and sometimes goes down and makes bad explosions.

I think this malfunction can be caused by the lack oil on rocker arms that causes wear on it, and all intake/exhaust valves gains clearances from 0,50mm to 1,00mm and the engines runs bad, and looses power and dont speed correct, or can be consequence of my bad jetting?

Thanks

lUIS

One of those eBay listings is incorrect:
* Low flow: 1.3 liters/ 1 minute
* High flow: 1.3L/ minute
That is the same flow spec, so it is not low flow vs high flow. Generally speaking a Nissan part number incremented by one is usually a minor variation

Regarding your question yesterday ... I would use the stock fuel pump. It flows more fuel than enough for twin carbs, and it has enough pressure. Mikuni say 2.8 psi, yet 2.6 works fine with Mikuni as many can attest to (that's what I ran for years with my Mikuni 40s). As for pressure, all it needs is enough pressure to move the fuel seat

I have twin Mikuni 40phh carbs, and Mikuni recommended fuel pressure is 2.84 - 4.98 psi, stock fuel pump have 2.6 psi pressure so i will need buy an electrical pump.

I saw one ebayNismo Electric Fuel Pump DATSUN 1200, but there are two manafacturer part numbers:

Manufacturer Part Number: low folow volume fuel
17010-A7600
MAX Delivery: 1.3 liters/ 1 mimute.
MAX Pressure: 0.45 kilograms/ centimeter2.
Low pressure specification for the sport carburetor.

Manufacturer Part Number: high flow volume fuel
17010-A7601
NISMO High Flow Volume Fuel Pump for Carburetor

SPECIFICATION:
Output Volume : 1.3L/min (at P=29kPa, 0.3kg/cm2)
Outside Diameter : 60mm
Length : 140mm
Intake Design : Outer Diameter 8mm
Outlet Design : Outer Diameter 8mm
Voltage : 7.0A


The first reference or second reference, according datsun 1200 com is the first one, but there are a big diference?


Thanks

Luis