1.6 Monty Carb in Maestro

[SimonR]

As part of the engine replacement of F153 I intend to change the original Maestro 1.6 carb (HIF44Ea, Carb Spec no: FZX1463) for a later-spec Montego 1.6 version (HIF 44e, MAC 10013). The advantage is that there is no over-run fuel cut-off valve or vacuum switch to worry about and as a result I've heard that these carbs are a better bet.

I've taken a look in the Burlen Fuel Systems catalogue and it seems that the only difference between the two carbs is the needle - the Monty carb has standard needle NZX8100BHC whereas the Maestro carb has standard needle NZX 8060BFM.

The question is: When I buy the rebuild kit, should I use the Maestro Needle or the Monty needle?

I'm thinking that the problems I'm currently experiencing with the car not idling/starting when cold is a carb problem and a complete rebuild will solve the problem. Furthermore eliminating the vacuum switch and ORFCO is a good step to take if I can.

Note that the car in question has a later-type unleaded Maestro S-Series 1.6 engine.

Has anyone got any thoughts?

Thanks :)

[E_T_V]

Hmm a very interesting dilemma there. Not one I have an answer to but here are my thoughts.

You could re-use your maestro carb and disconnect the fuel shutoff, however you are still left with the vacuum switch.

The monty carb was designed around the monty needle
If the inlet tract are identical on the monty and the maesty which I think they are, then I'd be tempted to use the monty needle all other things being equal.

My first thought was that perhaps the later needle was for unleaded fuel but I'm fairly sure that No 1.6's were ever designed to run on unleaded. The same needle wouldn't happen to be used from 92 ish onwards would it as it might be that the same needle/carb was used on a car that was subjected to the unleaded change? Well just a thought.

[MGTurbo]

I suspect very minor calibration changes between models of all ages and for all intents and purposes work the same so use whatever you can get hold of.

[Simon]

The Montego carb was designed for the 16HE54 spec engine which, from Oct 1988 onwards is meant to take unleaded fuel and works with the later ERIC engine combined fuel and programmed ignition ECU. No ORFCO valve or vac switch was deemed necessary. The needle etc setup was specified for unleaded fuel presumably and therefore would more than likely suit your later engine, with the necessary fuel (AUU1275) and programmed ignition ECU's (NNN 10009). I, and some other owners, have already disconnected the ORFCO valve without any noticeable effects on running. The issue here is whether the old setup can work effectively without a vacuum switch fitted. If it can, update to the later carb and save the aggro of these oftemn troublesome peripheral components.

[SimonR]

Thanks for your replies Folks :)

I guess I'll get the Monty needle in that case - I wondered which was more important - The correct needle for the Maestro or the correct needle for unleaded.

Originally posted by Simon
The issue here is whether the old setup can work effectively without a vacuum switch fitted. If it can, update to the later carb and save the aggro of these oftemn troublesome peripheral components.

That is indeed the issue! What does anyone think?

TBH I've no idea how the vacuum switch works or even what it does!

Do you reckon I can use the later carb without a vacuum switch, connecting the vacuum pipe from the ECU to the back of the carb?

[J199 HHG]

Use any old needle, it'll work sufficiently well that you won't be able to tell the difference!

I use 3.5litre needles in my 4.6litre V8 (as there aren't any listed for the 4.6), and it runs just fine.

Chris.

[Simon]

Study how the vacuum is arranged on an ERIC 1.6 Montego for clues. My guess is that you are right, the vac switch just uses an extra branch off the vac line from ECU to carb.

To throw an extra spanner in the works, there was a manual transmission 1.6 Maestro, unleaded spec from 88 to 92 using the old 2 ECU setup and not ERIC, using the original BFM needle. Refer to Legacy EPC and the Burlen fuel systems website. Carbs come out at about £157 + VAT IIRC.

In a moment of weakness I thought about converting my unleaded Maestro 1.6 to ERIC being as there was a new one on ebay, but it would have been a hassle to wire it up properly for my usual kind of "invisible mend".

[G Force]

I personally would have no worries over fitting the later carb to your maestro, The pro's definately outweigh the cons. The worst thing that can happen is the possibilty of slight hesitation at some point during warm-up under acceleration. The reason I say this is because on the later carb the extra acceleration whilst on choke is provided by the eric ecu applying additional stepper motor steps. The vacuum switch does this job on the early carb. The vacuum switch has no effect on fueling once the engine is up to temp. ;)

As for the fuel cut off valve, this was just an additional economy device, meant to equal approx 1 - 2mpg urban cycle when working, but due to its troublesome reliability it often made mpg matters worse.

The needle issue could go either way as there is not going to be much in it. You are in a good position to see which one best suits your driving style, and fuel economy. Try both, I suspect the maestro one might give a slightly better result. :)

The plumbing is easy one pipe carb to ecu.

Cheers Gary :)

[SimonR]

Once again, many thanks to all for your answers.

What I think I'll do is order a rebuild kit for the Monty carb but also order a Maestro needle as well so that I can try it with both. Then I can use the Monty carb with either needle and see what works best.

I'll also take a few photos in case rebuilding the SU would be an interesting article for Monstro. I guess you die-harders would be able to have it to bits and together again in a coupe of hours but it may make good reading for the layman such as myself.

On a related note, how can you tell if a stepper motor is good or not? The one currently fitted to F153 I suspect is broken because you can turn the brass barrel with your fingers even when the ignition is switched on (obviously I tried it before fitting it o the car); it does turn as expected though. The original one didn't allow this but also refused to move at all. I suspect I may be suffering from broken stepper motors as well as a few other things.

[MGTurbo]

Originally posted by F153JUE


On a related note, how can you tell if a stepper motor is good or not? The one currently fitted to F153 I suspect is broken because you can turn the brass barrel with your fingers even when the ignition is switched on (obviously I tried it before fitting it o the car); it does turn as expected though. The original one didn't allow this but also refused to move at all. I suspect I may be suffering from broken stepper motors as well as a few other things.

The outer of the stepper motor shaft should stay fixed, the emulsion tube inside should turn normally if the motor is removed or actuated electrically.