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Fuel Pump Pressure - NDIX Carb

Posted: Tue Apr 30, 2019 8:15 am
by Garrycol
Can someone tell me what fuel pressure and fuel flow the NDIX Carb requires.

Thanks

Garry

Re: Fuel Pump Pressure - NDIX Carb

Posted: Wed May 01, 2019 7:39 pm
by Garrycol
No one knows? I have heard 2.5psi but do not know what flow rate.

Cheers

Garry

Re: Fuel Pump Pressure - NDIX Carb

Posted: Thu May 02, 2019 8:55 am
by one2many
For the 36 NDIX I've also read that 2.5 psi is a good fuel pump pressure but also that anywhere between 2.5 and 4.5psi should work well. Flow rates for the ndix32 and 36 carbs is a good question However my Pinz and Haffy repair manuals do shed some light...well I think they do, also Jims "Goatwerx" website has some really good carb info.

Here is a relevant quote from the Pinz repair manual so 36ndix
"If fuel pump should be defective check diaphragms, suction-pressure valve and the return stop valve. The minimum feed at 4000 rpm amounts to 24 liters of fuel, the feed pressure to 0.3 bar". ....that's approx 4.3psi!
I guess it should read "24 litres of fuel per minute."

Here's one from my Haflinger manual (dated July 1962). Sorry but I realised the below comment applies to the Weber 32 ICS only after I typed it...thought I'd just leave it.
"......In case of trouble check the diaphragm and the dise valves and springs. It will be useful to check also the pump pressure by means of a pressure gauge. The pressure should correspond to 3.28-4.92 ft (1-1.5m) of column water". It also goes on to say a bit about plunger pressure. " The pressure should correspond to 4.27-5.9 ft (1.3-1.8m) column of water.".

Don't know If that will be of much help but there you go.

Re: Fuel Pump Pressure - NDIX Carb

Posted: Thu May 02, 2019 9:13 am
by one2many
Also I just remembered posting this thread ages ago, it was titled "zenith carb info pages" and the links in it have by far the best ndix carb information I've found...well worth a look at them if your about work on your ndix zenith.

Old thread.
I found the pages in the link below to be so informative that I thought it deserved a place somewhere on the board....perhaps "Tech Sessions" (??? Vince) Be sure to have a good look around the site...the "tech tips" link has a heap of different articles that are must reads for anyone interested in working on the Zenith 32/36/38 ndix series carbs. My favourite article is the one about "Jet Setting" ....how to check the true size of our jets and accurately resize them.

http://www.sparkingplugs.com/5.html

https://porsche356registry.org/article/46
Another thing he said somewhere in the link that others might find of interest...."Rule of thumb...6% reduction in MAIN JET size for every 1000 metre rise in sea level."

Re: Fuel Pump Pressure - NDIX Carb

Posted: Thu May 02, 2019 8:26 pm
by Garrycol
Thanks so much for that information - great stuff.

I have an electric fuel pump on my Haflinger 32 NDIX and I think the pressure is a bit high - I have now spotted a couple of 2-3 and 3-4 PSI on ebay so i might give a 2-3PSI pump a go.

Thanks for your response

Garry

Re: Fuel Pump Pressure - NDIX Carb

Posted: Fri May 03, 2019 12:55 am
by one2many
No worries, also a great idea IMO

https://www.demon-tweeks.com/au/malpass ... er-243259/

I'd never heard of the "Filter King" pressure regulator/filter before I saw the one on my Volvo tgb1314 (fitted to all tgb's as OEM fuel filter) and I reckon they are a great idea, I've been meaning to fit one to my Pinz for the very same reason you mentioned above. Note there are a few different variations in the Filter King "catalogue", the one fitted to the TGB series has a glass bowl not aluminium but otherwise appears to be the same.
Cheers

Re: Fuel Pump Pressure - NDIX Carb

Posted: Fri May 03, 2019 3:01 am
by Garrycol
Thanks for that - bookmarked those links for future reference and if the pump I get does not perform I will look at them - I like that last link with the combined filter/regulator - most regs are 0-140psi and 2.5 psi is just a blip on the scale.

Cheers

Garry