4a Resto: Fitting twin HIF6 SUs.

[Mimosa1974]

Hi guys.
Has anyone ever fitted the twin HIF6 carb set up (from Rover 2200 TC and Princess 2200) to a 4a and can provide advice / pictures, of the cars’ final set-up. I have the carbs, which have been refurbished, and I have a reasonable idea of the connections needed to link the two together but one of you helpful folk might have done this already and can advise what was needed to complete the ensemble, i.e. use some specific items (brackets, cables, connectors, etc, from a Rover, MGC, MGB, etc, or that you had to make yourself). I’ll get there but hoping to greatly reduce the inevitable guess work and frustrations along the way. Advice appreciated.
Cheers, David Ansell (Clyde Valley group).

[BlueTR3A-5EKT]

What needles do you expect to use?

HIF run exclusively bias or spring loaded needles.   TR needles are fixed.   The attachment of the needle into the piston will be one of your challenges or finding a suitable bias type profiled needle.

I too have a pair of HIF carbs that I have not fitted to my TR.

There is someone on here that has fitted twin HIF to a TR2.

Edited February 10 by BlueTR3A-5EKT

[Mimosa1974]

Good questions Peter (bias vs spring loaded needles) and I don’t have the answers. The carbs were refurbished by the very helpful Andrew Turner, so I’ll need to ask him. I have also spoken to Burlen’s tech desk and they will look through their library of pictures so see if they have examples of the non-standard fitting of twin-HIF6s. Fingers crossed. 

[BlueTR3A-5EKT]

It can be done.

You need to extract the bias needle from its top hat holder that is pressed on.  Then fit the top hat to a TR needle, SM or TW for standard.    I would expect a rolling road tune would be the best way to get the mixture correct using those carbs.

[stuart]

Do they clear the column on a right hand drive car? Ive got a feeling they dont.

Stuart.

[Lebro]

10 minutes ago, BlueTR3A-5EKT said:

It can be done.

You need to extract the bias needle from its top hat holder that is pressed on.  Then fit the top hat to a TR needle, SM or TW for standard.    I would expect a rolling road tune would be the best way to get the mixture correct using those carbs.

I would be very surprised if there wasn't an equivalent baised needle to the usual TR range. A session on minty lamb should find one (or two)

Bob

[david ferry]

I'll have to check, but I may have a set of rebuilt HS6 carbs - standard for a TR4a, if you get bored of the HIF6s

David

[Mimosa1974]

Thanks to those who responded to my query - although didn’t actually answer my question 🤣.  However, you certainly gave me additional food for thought about the appropriateness of the HIF’s biased needle configuration for use on a TR4a, so I wrote to the very helpful Andrew Tuner who confirmed that my HIF6 carbs were rebuilt using BDM profiled biased needles, which he has found suit the TR4 / TR4A engine, and which confirmed Lebro’s suggestion of an equivalent biased needle for the TR range. I can’t wait to try them out. I’ll follow up in a few months with pictures and a running report. Cheers, David

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[BlueTR3A-5EKT]

This could be a red herring.

The HS carbs fitted to Spitfire 1500 and Triumph 2500 saloons had a thermal control on the base of the main jets.   This was a continual problem item as it leaned the mixture when the engine was hot which caused very lumpy tick over.   Solution was to remove tge thermal device and fit regular uncontrolled jets.

HIF incorporate a thermal bimetallic strip inside the carb which is intended to lean the mixture slightly when it all gets hot under the bonnet.   That might give you lumpy tick over when stuck in traffic.

I’d consult the very late MGB owners who had this type of carb fitted as standard.    Do they have any problems?
The simple addition of an heat shield between exhaust and carbs could be the easiest and quicker solution if you do suffer with hot engine lumpy tick over 

[Mimosa1974]

Thanks again Peter. Good points.
I did contact the MGOC technical department for advice before going down this route* and they suggested a heat shield too but otherwise no routine problems (that’s not to say there aren’t individuals with troublesome HIFs so I will post the question about running performance in slow or stationary traffic). I will also fit an electric fan, as I have done for my PI 6, with remote switch which should go a long way (together with the shield) in preventing problems before they start. 
Much appreciated. 
David 

*. Imagine that; a classic car club with a dedicated technical help desk! There was even a real person too, who picked up the phone after two rings, and was friendly, knowledgeable and helpful. I also find that the MGOC have an incredibly well-stocked shop and dedicated repair facilities. Just imagine that kind of far-sighted investment in the support of club members. Oh, and reasonable subscription rates too. Certainly a good business model that others could learn from - or not. 

 

 

[Mimosa1974]

PS. Forgot to add that whilst researching HIF carbs, I found that both Rolls-Royce, but more so Volvo, used the HIF6 in vast numbers for stationary engine situations (generators) so must check how they overcame any heat issues, or maybe they didn’t have any? I’ll try to find out. 
 

[BlueTR3A-5EKT]

6 hours ago, Mimosa1974 said:

Thanks again Peter. Good points.
I did contact the MGOC technical department for advice before going down this route* and they suggested a heat shield too but otherwise no routine problems (that’s not to say there aren’t individuals with troublesome HIFs so I will post the question about running performance in slow or stationary traffic). I will also fit an electric fan, as I have done for my PI 6, with remote switch which should go a long way (together with the shield) in preventing problems before they start. 
Much appreciated. 
David 

*. Imagine that; a classic car club with a dedicated technical help desk! There was even a real person too, who picked up the phone after two rings, and was friendly, knowledgeable and helpful. I also find that the MGOC have an incredibly well-stocked shop and dedicated repair facilities. Just imagine that kind of far-sighted investment in the support of club members. Oh, and reasonable subscription rates too. Certainly a good business model that others could learn from - or not. 

 

 

You are missing the crucial part here.  

It is a commercial spares company, like Rimmers, using the word CLUB in its name.  
Search MGOCLtd.  https://find-and-update.company-information.service.gov.uk/company/01204646