Quick and dirty SU Tuning

[Mark Maras]

 It's possible he has Gros Jet needle valves if there's a steel ball bearing in one end of the needle. The standard needles have a rounded end that contacts the float tab and a cone shaped end that is the fuel sealing surface. The cone shaped end is either rubber? or brass.

[dat260]

17 hours ago, 240260280 said:

You can make paper gaskets.  Scan the bottom of you bowl lid or use the template below. 

Scale to correct size using regular paper and a printer. When you have the scaling right, put thicker paper or gasket paper in the printer then print to it and cut out with scissors or Xacto knife.

 

Thanks 240/260/280

 

[dat260]

10 hours ago, Mark Maras said:

 It's possible he has Gros Jet needle valves if there's a steel ball bearing in one end of the needle. The standard needles have a rounded end that contacts the float tab and a cone shaped end that is the fuel sealing surface. The cone shaped end is either rubber? or brass.

That's correct Mark

 

[jalexquijano]

I am having a heck of time trying to adjust the jet adjustment/ fuel mixture knobs to get the browish tanned color spark plug. Is there any better tool than the Gunson Colortune i bought on ebay? Im at 4 turns at each of the carbs on my 72 240z!

[Mark Maras]

On 6/20/2017 at 10:16 PM, dat260 said:

Thanks guys, I will tackle this issue my next day off. I found out my carbs are from 70/71 series. The float specs are different for those years.

 

Stanley, my needle valve does not have a rubber tip and the tip is rounded. I also cleaned them last time they were out, needles and banjo fitting, they were dirty. The problem Iam facing now is that Iam running out of bowl gaskets. Everytime I open the lid the gaskets warps. It took two weeks to get them from ztherapy. Can I install the lids without gaskets?

I appreciate your input

 

 Which direction are the Gros Jet needle valves installed? The rounded end (not the ball) is the contact point to the float tab (tang).They were supposed to be a better design (better mouse trap) but they too leaked at times undoubtedly from foreign matter in the valve. Could some more crud be in them? I've not installed the lids without gaskets before. I don't see why it couldn't be done temporarily. The float will be a little lower (the thickness of the gasket) but I doubt that will affect anything. I doubt that most floats are set exact.

[Mark Maras]

1 hour ago, jalexquijano said:

I am having a heck of time trying to adjust the jet adjustment/ fuel mixture knobs to get the browish tanned color spark plug. Is there any better tool than the Gunson Colortune i bought on ebay? Im at 4 turns at each of the carbs on my 72 240z!

 What color are the plugs at 4 turns down?

[7tooZ]

I have always thought the color of plugs should be checked after driving the car, not just reving up the engine. So I have always driven on the freeway near a rest stop and coasting in from speed with the engine off. Then pull the plugs to examine. Must be the backyard mechanic method ??????


Don's iPhone using Classic Zcar Club mobile

[Patcon]

Checking plugs after revving is useless! Check them after being driven like suggested

Adding turns is just gonna put more fuel down the exhaust for more popping. Get a wideband sensor!!!!

[jalexquijano]

Which sensor do you recommend? Ive seen several in amazon. Including one bosch brand bundle

[Patcon]

http://www.ebay.com/itm/INNOVATE-MTX-L-DIGITAL-WIDEBAND-UEGO-AFR-GAUGE-KIT-Marine-Powersport-3845-/182173494001?epid=1017782213&hash=item2a6a62eaf1:g:OVwAAOSwSdZWg~ri&vxp=mtr

or one of the the other Innovate kits

[jalexquijano]

It looks better than this one:

https://www.amazon.com/gp/product/B01F46VJ4U?ref_=sr_1_2&qid=1497022242&sr=8-2&keywords=wideband o2 sensor kit&pldnSite=1

Do you concur??

[Patcon]

They will probably both work for what you need. Jegs sells the AEM too