Fuel delivery

[datrod]

Just something I made over the weekend. New fuel rail for my Z car.

 

[metalmonkey47]

Very nice. It looks super clean.

[MicroMachinery]

Wow, that's awesome. How much would a 4-cyl version run? :cool:

[jalexquijano]

where did you get these type of hoses? does it stop the fuel percolation? I want to remove the stock fuel rail and install a system as yours.

[datzenmike]

This thread is 4 years old.....

[russaroll]

Happy birthday

[racerx]

very nice!

[datzenmike]

 

This has a return line to the tank which is good. Cool gas is constantly being pumped past the carbs. However that 'fuel rail' would work better if it was over closer to the carbs. This would shorten the lines to the SUs that would have stagnant gas in them absorbing heat.

 

All return lines need a restriction in them. Without this restriction the gas would just return to the tank rather than push into the carbs. The restriction would allow pressure to build on the carb side. About a 1mm hole would do.

[jalexquijano]

well down here in Panama we are still trying to figure out this percolation issue. stuck in traffic, car starts to stumble lowering rpms from 900 to 700 back and forth and when engine heat rises falls to 200 rpm. park the car, open the Hood, pull the plugs and all came out black sooty. Its weird that even after installing heat shield extensions covering the fuel bowls of both SU Carbs i am still having this issue. Its really uncomfortable to drive this way on traffic.

[datzenmike]

Black sooty is over rich. Maybe flooding? Not sure if the SU can flood like a regular carb. There is an over flow fitting on the float chamber usually fitted with a hose traveling down beside the engine so if there is flooding, the excess gas is dumped on the road.

 

 

#5 is the over flow tube. Looks for yours and make sure it's open. Gas boiling in the float chamber may pressurize it if the overflow is closed off and force gas through the jet. Route a hose down beside the engine beside the oil pan and away from the hot exhaust.

[Charlie69]

Install a fuel return line with the return line being a metered orifice to help keep fuel in the carbs.

 

1985 720 Z24 return line.

 

 

 

There is a metered orifice in the return line that helps get fuel to the carb/carbs.

[jalexquijano]

The Airtex 8012s electric fuel pump is pushing 4.3 to 4.5 psi to the SU CARBS! Should i also get a Malpassi King Fuel Filter regulator so i can lower the psi to 3.5??? Could this also be the cause of percolation? or should i leave the pressure as it is!!

[datzenmike]

Fuel boiling isn't caused by pump pressure. 

 

 

One of your problems is over rich causing those sooty plugs so yeah I would definitely drop the pressure to the level recommended for use on SU carbs.

[jalexquijano]

OK! ill need to get a good fuel pressure regulator to lower to 4 psi! Malpassi fuel pressure regulator!!!!