datsun 510 w/ L20b dual weber. having problems tuning.

[DatsunSwag22]

so i just rebuilt my l20b motor 280z pistons n new head n i can't figure out the jetting on the carbs. one min over n the next under. dual weber 40 doc.

i dont kno wat to do. please help. 

[hobbes_the_cat]

There are some good basic tuning guides pinned on this site.

I have found that a Wideband o2 gauge is a valuable tool when dialing in twin carbs. It tells you exactly what your A/F ratio is rather than trying to guess by reading the plugs.

[flatcat19]

UniSyn. Brilliant.

 

 

Or a long piece of small diameter rubber hose.

Turn till you barely hear a hiss out of each port.

[LenRobertson]

I searched YouTube for "Weber DCOE tuning" and found a bunch of vids. I have no idea if they will help you, but maybe worth looking at. A couple of links to Ratsun pages if you haven't found them:

 

http://community.ratsun.net/topic/27094-weber-dcoe-stock-jetting-information/

 

 

http://community.ratsun.net/topic/6117-weber-tuning-guide/

 

 

Len

[DatsunSwag22]

do u guys kno wat jets i need?

[TENDRIL]

wtf is a dco.?  DCOE?  DCOM?

[TENDRIL]

jets can get expensive real quick.

 

so are you tuning for street or track ?

 

whats your dizzy setup?

 

cheap o2 sensor can save you some monies/

[EricJB]

1 Ignition timing must be set properly.

2 Fuel pressure regulator set at 3psi.

3 No vacuum leaks.

 

 Find out what size venturies you have.

 

Venturi size x4 = main jet

Main jet +40 = air correction jet

That should get you close.