Vapor lock questions for the hotter climate guys

[jalexquijano]

So how do i solve this issue??? Removing the rail and replacing it with rubber hoses with AN1 fittings? Im just fed up of this heat soak!! Percolation!! whatever!!

Edited October 17, 2016 by jalexquijano

[Mark Maras]

2 minutes ago, jalexquijano said:

So how do i solve this issue??? Removing the rail and replacing it with rubber hoses with AN1 fittings?

 That's what I would do. I think it will have the greatest impact on the problem. Let us know how well it works if you go that route.

[Namerow]

Just make sure that you use fuel-rated hose and mount it so that it won't chafe on a sharp edge. The CZCC members have too much invested in this car to lose it now .

[Stanley]

AN hoses are safer, they won't leak if done right. But they need something threaded at each end to attach to, otherwise they're useless. If you have an old-style mechanical fuel pump on the engine you can unscrew the outlet hose barb and put a (BSPT to NPT) elbow or tee and hook the AN hoses to that with an AN/NPT adapter. Similar if you have an electric fuel pump with threaded outlets in the engine bay. You'll have to replace those stock banjo bolts with (metric) banjo bolts with threaded connections at the inlets. They're available, I forget where. Then you can hook it up to the AN hoses. Kind of a lot of plumbing.

[jalexquijano]

Where do i purchase AN hoses and adapters? Any kit available for our cars?

[zKars]

https://www.anplumbing.com/

[jalexquijano]

well down here in Panama we are still trying to figure out this percolation or vapor lock 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. No mechanic has been able to find a  solution!!!!!

[Mark Maras]

 Maybe an infra-red thermometer would help find the hot spots in the fuel system.

[Zed Head]

On 10/17/2016 at 1:17 PM, jalexquijano said:

So how do i solve this issue??? Removing the rail and replacing it with rubber hoses with AN1 fittings? 

Everyone told you to do this.  Did you do it yet?!  Nothing will change until you change something!

[Stanley]

So, excessive heat in the engine bay causes rich condition fouling the plugs ? Can anyone explain that ? Because I don't get it at all, and I'm trying to learn something here.

Vapor lock plus fouled plugs would make a crappy driving experience, but it's possible to have two or more unrelated problems at the same time.

I remember posting a suggestion to get a synchrometer or unisync and set the mix with it, following the procedure in the FSM exactly. If you did that, at least carb settings can't have anything to do with the problem.

[Zed Head]

The image attached is how Nissan explained it, in their 73-74 Fuel system Modification Plus manual.

 

[Stanley]

I won't argue with the book.

And regarding the AN fittings, I was sort of trying to discourage you from doing that in my previous post. Sorry, but it's more a nice, but time-consuming "finishing touch" kind of project for a Z car, than a solution for the vapor lock problem. A skilled technician with the right tools and experience building AN hose systems wouldn't have a problem (except maybe finding the right banjo bolts to fit the SU's), but it would be quite a project for anyone else. Why not just use good fuel hoses and clamps ? Way easier in my opinion, and just as good for keeping fuel lines away from heat sources. You could actually get the hoses, clamps, tee fitting, etc. installed yourself and be back on the road in a day or two.

If you're too in love with the AN idea (I agree it would look cool) find the banjo bolts first. That will probably take a month. Also look up or measure all the fittings, getting correct hose sizes, lengths, and thread types for your project(another month). Then go to a place that makes hoses (for trucking, industrial, HVAC, race cars, etc.) and have them cut the hoses and install the fittings and adapters (20 minutes). Then install it yourself and you're done.