zenith Auxiliary Enrichment removal procedure help

earlyaircooled · 03-12-2013, 08:29 PM

I want to remove the auxiliary enrichment parts from 2.2t zeniths. Can someone give me a step by step procedure, what needs to be done? Thank you

VFR750 · 03-13-2013, 02:01 AM

WIll answer later in more detail Basically remove the system and plug the holes.

earlyaircooled · 03-13-2013, 07:38 AM

I know I need to plug the three pipes coming out at the bottom of the car. How do I plug the hole in the middle of the car when I take the main unit part off?

Thanks

1QuickS · 02:04 PM

I drill and partially tap holes to receive threaded aluminum plugs or standard setscrews. The aluminum plug just below the accelerator pump cover is required since that bore is now 46mm and the previous casting feature would become a hole if not plugged first. Screw the slotted metering screw at the middle cylinder shut. There is a supply jet inside one of the fuel bowls and it can be plugged with a M4 setscrew or left as is.

VFR750 · 03-13-2013, 02:05 PM

Just tap the big hole for a M8 thread.

McMaster Carr sells brass bolts and Aluminum washers. Just buy some bolts and cut them shorter as required.

The mixture screw just gets screwed in as far as it goes.

The other holes for the screws can be left alone.

VFR750 · 03-13-2013, 02:07 PM

Paul,

Beautiful work, as usual.

Nostril Cheese · 03-13-2013, 02:08 PM

A lot of people dog the Zeniths, but they are good carbs WITHOUT the aux. enrichment. I just pull the connectors for the solenoids, cap off the vacuum ports and screw in the mixture screw fully. Agreed, the above pics are VERY nice work.

James Brown · James Brown's Garage

yep you can just screw in the mixture screw and they look stock, put a dab of silicone in the vacuum lines and your done

earlyaircooled · 03-13-2013, 02:22 PM

Since the carbs are already built I dont think I want to drill and tap anything. I'll do the plug vacume lines method, thanks to all that responded. This may be silly question, I have the stock vacume advance distributor, what line does it use for vacume, in other words what do I hook it up to?

Thanks again

Nostril Cheese · 03-13-2013, 02:30 PM

Correct me if I'm wrong here, but a 2.2T should have a mechanical advance setup. Marelli as well.

earlyaircooled · 03-13-2013, 02:48 PM

It does have Marelli and that's right it is mechanical advance, I kinda forgot that....thanks again all. And Thanks Nostril Cheese for PMing me and sending me your number I'll give you a call!

Fastdog911 · 03-13-2013, 02:49 PM

what is the main advantage of doing this? Is this common practice?

James Brown · James Brown's Garage

the aux enrichment was a bandaid to reduce pollution at cold temps. best to remove it as it doesn't work well

PropellerHead · PropellerHead's Garage

Actually this circuit is to deal with closed throttle overrun emissions. Not cold weather emissions. it does reduce decel exhaust pop but isnt bad without it either.
Cars equipped with Zeniths may have Bosch or Marelli distributors, it wasn't universal even within a given model year which came with Zeniths.
It does not affect on-throttle performance or idle (below the cut off RPM) where the system is disabled. But it offers the 'opportunity' for vacuum leaks, etc.
I disabled mine during a rebuild using lead shot to close off the passages. I then used vacuum caps on the ports which has another side benefit, I can use individual port vacuum gauges for throttle synching. I have a motorcycle 4 gauge set up which I connect to all three on one bank and one port on the other bank for easy real time synch of the idle bypass screws. Works great and far more sensitive and accurate than a uni-syn!

James Brown · James Brown's Garage

learn something new every day, anyway, get rid if them

yundar · yundar's Garage

Hi all!

I am running a set of Zenith 40 TIN's on a 2.7L. I have received a lot of tuning help from James and Paul. Thanks guys! The motor is a 74 CIS that is stock aside from the carb conversion and an MSD 6AL ignition. I am using 32mm venturies made by PMO and designed for a Weber. I realize this is not the optimal set up (sorry Paul) but I have not been able to find venturies specifically for the Zeniths. I am using 135 main jets and 50 idle jets. The car idles a little fast at 1200rpm. I have a set of 55 idle jets to try and see if that makes a difference. The carbs sit on 40mm PMO manifolds. I used the rubber isolators and longer studs going into the heads.
I removed the auxiliary enrichment system. I put rubber caps on the lower vacuum ports and a pressed in plastic cap on the upper center port. The first time I did this I siliconed the plugs in but it sucked little chunks of silicone into the carbs. Not good! The upper center mixture screw was screwed down until it bottomed out. I am not running any vacuum to the distributor as I believe it is a vacuum retard model and not necessary. Correct me if I am wrong on this! I plugged the vacuum port on the dizzy with a plastic cap.
The car runs good with plenty of pep now that I have the jets sorted out. I ordered a few sizes up and down on the jets but have not had a chance to play with them. The only issue is the high idle and now that I am reading this to myself I wonder if I just have a vacuum leak around my makeshift plugs? Duh! I will make some of the threaded kind! I don't know what I did with the port by the accelerator pump? I will have to go back and check that too.
Over all I am pleased with the Zeniths. Good luck with yours and thanks again to all who helped. Andy.