Revington Throttle Linkage for CR version

[Mimosatr6]

I have purchased a Revington overhead throttle linkage system. This is great as it makes the butterfly’s open together but n the CR the butterfly’s are held shut by a high vacuum so suddenly snap open when you press the accelerator. In order  to get a smooth throttle opening I need to fit the original Triumph cam back on the help with this. There is an additional Revington kit for this however the kit is now missing an essential part as the main rod is no longer available and they cannot remanufacture it.

 

So I have to either buy a second hand unit for the rod or manufacture one myself. If I have to manufacture one I need some decent photographs of how this links to the overhead bar and if possible get dimensions too. Unfortunately even in the instruction manual the photographs leave a lot to be desired and do not show how the rod connects to the overhead bar nor do they contain any dimensions.

 

So the question is does anyone on the forum have the overhead Revington Linkage on their TR6 CR? If so can they please photograph it in detail how it is set up for me so I can try to remanufacture the missing rod.

 

Better still if someone has an old one they are not using and can sell me the rod I would be grateful. Below is the only photograph I can get.

[boogie]

Is this the part you're looking for?

https://fredmillturnparts.com/my-manifolds/cr-tr6-and-2-5pi-mk2-saloons-and-estates/

[Mimosatr6]

Unfortunately no. To fully explain, I am now using an aftermarket solution manufactured by Revington TR. Their solution provides an overhead linkage offering individual adjustment of the butterfly's and overcomes the problem of worn linkages on early cars and with later CR TR6 models whereby the original linkage had limited adjustments making it hard to balance the butterfly's. The current aftermarket solution works with an overhead linkage as shown below and provides significantly improved adjustment of the butterfly’s providing a much smoother idle and low speed running for CR’s with a worn linkage and a more accessible adjustment for earlier CP models.

 

However the down side is that, as can be seen in the photo below, the throttle cable connects directly to the linkage. This arrangement doesn’t give CP drivers any problems but it is a bit of an issue for drivers of CR models. On CR models this direct arrangement doesn't provide enough throttle control. I was informed this is a symptom of the CR engines design, the different cam on CR engines gives these models a higher vacuum in the throttle bodies over previous the CP cars (14 as opposed to 9 on earlier models) this effectively holds the butterfly’s closed requiring more pressure on the accelerator to break the seal. So when I try to pull away from a standstill the butterfly’s suddenly pop open causing a sudden rush of power rather than the progressive power required to pull away smoothly. Triumph solved this by fitting a cam mechanism to the accelerator mechanism of later cars so I need to refit the original cam mechanism to solve this.

 

 

Unfortunately this requires a supplementary modification kit Revington used to sell for fitting to CR versions however that kit is now out of stock and they currently they cannot manufacture it. So I am searching for anyone who has a CR model with the full Revington modification who can supply a photo so I can copy it.

Edited September 2, 2019 by Mimosatr6

[Andy Moltu]

On 8/30/2019 at 8:56 PM, Mimosatr6 said:

I have purchased a Revington overhead throttle linkage system. This is great as it makes the butterfly’s open together but n the CR the butterfly’s are held shut by a high vacuum so suddenly snap open when you press the accelerator. In order  to get a smooth throttle opening I need to fit the original Triumph cam back on the help with this.

 

Not quite sure how the vacuum would hold the butterflies shut? The butterflies pivot around their centre so the vacuum should be applying an equal force to the top and bottom of the butterflies -sucking the lower half closed whilst an equal force sucks the upper half open (or vice versa). I can't see why this should result in snap opening  - perhaps something else is sticking or there is a slight imbalance between  the throttles which can give a jerky feel when opening the throttle

[stuart]

6 minutes ago, Andy Moltu said:

Not quite sure how the vacuum would hold the butterflies shut? The butterflies pivot around their centre so the vacuum should be applying an equal force to the top and bottom of the butterflies -sucking the lower half closed whilst an equal force sucks the upper half open (or vice versa). I can't see why this should result in snap opening  - perhaps something else is sticking or there is a slight imbalance between  the throttles which can give a jerky feel when opening the throttle

Thats taken from Revingtons site stating about the high vacuum, not entirely true but flogs you an expensive bit of kit, I have just had to get a CR set up properly after it had been butchered by an incompetent garage and it did involve having to get the shafts built up to compensate for wear and the links remade to take up wear and butterfly plates properly centralised. (Also throttle pedal re-bushed which a lot of people over look) Car would then happily tickover right down to about 450rpm if required and full throttle opening restored.

Stuart.

[Mimosatr6]

As you may be able to see my throttle bodies have been completely rebuilt and re-bushed this final step of adding the new linkage was an attempt to improve the butterfly adjustment. I must admit if I drive it like a racing car the issue isn’t a problem and the car accelerates better than ever but for more sedate driving I would like to get increased pedal control. Andy raises a good point regarding the vacuum but I am assured this is the explanation for the snatchy response. Cables are free and the linkage seems to move freely.

[Andy Moltu]

Snatchy response can be down to minor imbalance of the throttles which affects things in 2 ways - some cylinders are fed air and fuel before others and the vacuum applied to the metering unit may be messed up by this. The CR throttles had two balance pipes between them (The CPs had one) to try and even the vacuum to the metering unit but even so at small throttle openings the relative airflow between the different pairs of inlets can be relatively significant if the throttles are not perfectly balanced and the fuel required by each cylinder may not reflect that which is delivered by the injectors). At wide throttle openings things are much more even.

[Mimosatr6]

Hi Andy, I did experience exactly what you describe pre the rebuild but the throttle bodies are much better now. Especially at low speed, 30MPH, where the issue you describe caused a horrible kangaroo effect not as bad as a true Kangaroo start but you could feel some cylinders were pushing and others not at 30 MPH giving a horribly jerky ride. Now at 30MPH the revs are smooth and even so consequently the ride is much more comfortable plus now even a small push on the accelerator and the engine willingly pulls from low revs. This issue is only evident when pulling away under load and the engine has been idling. It’s more like turbo suddenly coming on stream than the lumpy response from imbalance between the throttle bodies.

 

However how would you recommend I check for balance apart from visually checking the butterfly’s all close properly and open simultaneously? Is there a trick to ensuring this aspect is correctly set up?

[stuart]

21 minutes ago, Mimosatr6 said:

Hi Andy, I did experience exactly what you describe pre the rebuild but the throttle bodies are much better now. Especially at low speed, 30MPH, where the issue you describe caused a horrible kangaroo effect not as bad as a true Kangaroo start but you could feel some cylinders were pushing and others not at 30 MPH giving a horribly jerky ride. Now at 30MPH the revs are smooth and even so consequently the ride is much more comfortable plus now even a small push on the accelerator and the engine willingly pulls from low revs. This issue is only evident when pulling away under load and the engine has been idling. It’s more like turbo suddenly coming on stream than the lumpy response from imbalance between the throttle bodies.

 

However how would you recommend I check for balance apart from visually checking the butterfly’s all close properly and open simultaneously? Is there a trick to ensuring this aspect is correctly set up?

You need an air flow meter to get it right like this https://www.ebay.co.uk/itm/Synchrometer-Carburettor-Carb-Balancer-DCOE-DHLA-Dellorto-40-45-48-Models/371167530307?hash=item566b4f0d43:g:PSYAAOSwvjtcptQl

Stuart.

[PodOne]

Shame they are so expensive otherwise I'd consider six of them all calibrated to read the same and go from there. Or maybe a cheaper more accurate digital solution to give real time information across all six pots which would make the balancing spot on.

Andy

[astontr6]

On 8/30/2019 at 8:56 PM, Mimosatr6 said:

I have purchased a Revington overhead throttle linkage system. This is great as it makes the butterfly’s open together but n the CR the butterfly’s are held shut by a high vacuum so suddenly snap open when you press the accelerator. In order  to get a smooth throttle opening I need to fit the original Triumph cam back on the help with this. There is an additional Revington kit for this however the kit is now missing an essential part as the main rod is no longer available and they cannot remanufacture it.

 

So I have to either buy a second hand unit for the rod or manufacture one myself. If I have to manufacture one I need some decent photographs of how this links to the overhead bar and if possible get dimensions too. Unfortunately even in the instruction manual the photographs leave a lot to be desired and do not show how the rod connects to the overhead bar nor do they contain any dimensions.

 

So the question is does anyone on the forum have the overhead Revington Linkage on their TR6 CR? If so can they please photograph it in detail how it is set up for me so I can try to remanufacture the missing rod.

 

Better still if someone has an old one they are not using and can sell me the rod I would be grateful. Below is the only photograph I can get.

 

On 8/30/2019 at 8:56 PM, Mimosatr6 said:

I have purchased a Revington overhead throttle linkage system. This is great as it makes the butterfly’s open together but n the CR the butterfly’s are held shut by a high vacuum so suddenly snap open when you press the accelerator. In order  to get a smooth throttle opening I need to fit the original Triumph cam back on the help with this. There is an additional Revington kit for this however the kit is now missing an essential part as the main rod is no longer available and they cannot remanufacture it.

 

So I have to either buy a second hand unit for the rod or manufacture one myself. If I have to manufacture one I need some decent photographs of how this links to the overhead bar and if possible get dimensions too. Unfortunately even in the instruction manual the photographs leave a lot to be desired and do not show how the rod connects to the overhead bar nor do they contain any dimensions.

 

So the question is does anyone on the forum have the overhead Revington Linkage on their TR6 CR? If so can they please photograph it in detail how it is set up for me so I can try to remanufacture the missing rod.

 

Better still if someone has an old one they are not using and can sell me the rod I would be grateful. Below is the only photograph I can get.

Hi Mimosa! Yes I do have a Revington Over head linkage on my 1973 TR6. It is over 20 years old  and I have not had any problems with it. I am not certain that the construction of it is exactly the same as your picture as my air box is in the way for a full view. I will look for the instructions in my file. I have always set the balance up using a Crypton  carb balancer, which gives very 

accurate results. I am not certain  how your vacuum holds the butterflies shut as my system has individual adjusting rods per butterfly pair. I have never had any kangaroo problems!

Bruce

[super6al]

On 9/2/2019 at 10:45 AM, stuart said:

Thats taken from Revingtons site stating about the high vacuum, not entirely true but flogs you an expensive bit of kit, I have just had to get a CR set up properly after it had been butchered by an incompetent garage and it did involve having to get the shafts built up to compensate for wear and the links remade to take up wear and butterfly plates properly centralised. (Also throttle pedal re-bushed which a lot of people over look) Car would then happily tickover right down to about 450rpm if required and full throttle opening restored.

Stuart.

My car has worn spindles & linkages. I have managed to improve take up by rebushing the pedal & balancing the throttles to a point by compromising between idle & part open throttle, but feel performance is not optimised.

 I'm interested in how the spindles can be built up. I've seen writes up about soldering the spindles or rebushing the bodies. Is it something that can be done DIY? 

Alan

[colin3511]

Alan,

You can machine them and fit a small bearing in there. Only room on CP bodies as the spindle diameter is smaller. Difficult to see on attached photo but they have bearings on each body. No play and very smooth.

You need to be able to machine a counterbore on the same centre line as the spindles. If you are careful, you could do it on a pillar drill.

Colin

[stuart]

On 9/3/2019 at 3:04 PM, super6al said:

My car has worn spindles & linkages. I have managed to improve take up by rebushing the pedal & balancing the throttles to a point by compromising between idle & part open throttle, but feel performance is not optimised.

 I'm interested in how the spindles can be built up. I've seen writes up about soldering the spindles or rebushing the bodies. Is it something that can be done DIY? 

Alan

I had them built up with braze then machined back to correct size.

Stuart.

[super6al]

Thanks Gents - didn't mention in the post but mine is also a CR version. Looks like its not a DIY job then.

[Mimosatr6]

On 9/3/2019 at 9:35 AM, astontr6 said:

 

Hi Mimosa! Yes I do have a Revington Over head linkage on my 1973 TR6. It is over 20 years old  and I have not had any problems with it. I am not certain that the construction of it is exactly the same as your picture as my air box is in the way for a full view. I will look for the instructions in my file. I have always set the balance up using a Crypton  carb balancer, which gives very 

accurate results. I am not certain  how your vacuum holds the butterflies shut as my system has individual adjusting rods per butterfly pair. I have never had any kangaroo problems!

Bruce

Bruce, Apoliges for the slow response I have been abroad.However if you can help with instructions or photo I would be very grateful. It is the top of the linkage that I cannot figure out, how to fix the bar to the rod that runs accross the top of all the throttle bodies? Going to try and make a linkage so any photos would help:)