Throttle body rebuild and butterfly adjustment

[super6al]

On 12/17/2023 at 1:15 PM, Jonny TR6 said:

Hi Alan - happy to pop my tin of Molykote in the post when I’ve finished with it if you want to use it. I can’t imagine too many situations where I’ll need it again and happy to help out a forum member.

They’re 400ml tins, so doubt I’d use more than 50ml and it can then be passed on to others who are doing the same.

Thanks that very kind of you - obviously I'll cover the postage. Please let the forum know how it goes. Just wondering if it can be applied to the spindles to lubricate & seal? I did a quick bodge/repair to spindles 1&2 and 3&4 back in 2021 by using plumbers solder to fill in the worn areas. Its still appears to be holding up but I'm going to strip them down to check in the next couple of weeks. I'm currently doing spindle 5&6 as I noticed some movement in this one and it was not fully returning when warmed up. I heard people say its weak return springs but I think its wear on the shaft causing the butterfly to stick slightly. Don't know if the CP spindles are the same but on the CR when the linkage operates there's a tendency for it to try & push the spindle upwards & across creating a wear pattern on half of the spindle. Unfortunately new spindles don't seem to be available unless as part of a complete refurbished set.  

[Ransomes256]

1 hour ago, super6al said:

Thanks that very kind of you - obviously I'll cover the postage. Please let the forum know how it goes. Just wondering if it can be applied to the spindles to lubricate & seal? I did a quick bodge/repair to spindles 1&2 and 3&4 back in 2021 by using plumbers solder to fill in the worn areas. Its still appears to be holding up but I'm going to strip them down to check in the next couple of weeks. I'm currently doing spindle 5&6 as I noticed some movement in this one and it was not fully returning when warmed up. I heard people say its weak return springs but I think its wear on the shaft causing the butterfly to stick slightly. Don't know if the CP spindles are the same but on the CR when the linkage operates there's a tendency for it to try & push the spindle upwards & across creating a wear pattern on half of the spindle. Unfortunately new spindles don't seem to be available unless as part of a complete refurbished set.  

This is where sealed bearings improve throttle control and seal against air ingress but do require the bodies to be  accurately machined. Did this on a friends car when he converted standard throttle bodies to EFI.

Neil

 

[Jonny TR6]

Just now, Ransomes256 said:

This is where sealed bearings improve throttle control and seal against air ingress but do require the bodies to be  accurately machined. Did this on a friends car when he converted standard throttle bodies to EFI.

Neil

 

Would be great to have sealed bearings and can only imagine how smooth it would be, however, the thought of machining accurately enough fills me with dread ! 

Al - wondering if you have a slightly bent spindle ? The screws can take some force to undo, which requires a good old push down to ensure the screwdriver tip fully engages. Even a slight warping could cause an over exaggeration when the spindle warms up. 

You could try swapping spindles into different throttle bodies, then seeing if the sticking occurs. Pop them in the oven to replicate them heating up on-car.

As for sealing the spindle to body hole, I do think the Molykote will help a lot. If the spindle is straight there should be a miniscule air gap once sprayed up.

If your spindle is a bit dicky try trzzz on ebay. He should have a spindle or two knocking about and you can save a bit of money by cleaning them up yourself.

[PodOne]

3 hours ago, Jonny TR6 said:

Would be great to have sealed bearings and can only imagine how smooth it would be, however, the thought of machining accurately enough fills me with dread ! 

Al - wondering if you have a slightly bent spindle ? The screws can take some force to undo, which requires a good old push down to ensure the screwdriver tip fully engages. Even a slight warping could cause an over exaggeration when the spindle warms up. 

You could try swapping spindles into different throttle bodies, then seeing if the sticking occurs. Pop them in the oven to replicate them heating up on-car.

As for sealing the spindle to body hole, I do think the Molykote will help a lot. If the spindle is straight there should be a miniscule air gap once sprayed up.

If your spindle is a bit dicky try trzzz on ebay. He should have a spindle or two knocking about and you can save a bit of money by cleaning them up yourself.

If you fancy it have a look here https://www.fredmillturnparts.com/throttle-bodies being impressed Martins other bits of kit. 

[Jonny TR6]

12 hours ago, PodOne said:

If you fancy it have a look here https://www.fredmillturnparts.com/throttle-bodies being impressed Martins other bits of kit. 

Very nice Andy - in an ideal world it would be worth doing, although in my case I have low leakage on the spindles and butterflies, so looking forward to seeing how they all balance up.

[super6al]

On 12/18/2023 at 4:35 PM, Jonny TR6 said:

Would be great to have sealed bearings and can only imagine how smooth it would be, however, the thought of machining accurately enough fills me with dread ! 

Al - wondering if you have a slightly bent spindle ? The screws can take some force to undo, which requires a good old push down to ensure the screwdriver tip fully engages. Even a slight warping could cause an over exaggeration when the spindle warms up. 

You could try swapping spindles into different throttle bodies, then seeing if the sticking occurs. Pop them in the oven to replicate them heating up on-car.

As for sealing the spindle to body hole, I do think the Molykote will help a lot. If the spindle is straight there should be a miniscule air gap once sprayed up.

If your spindle is a bit dicky try trzzz on ebay. He should have a spindle or two knocking about and you can save a bit of money by cleaning them up yourself.

Thanks for the tip about Trzzz I messaged Carl to day & has a new 5&6 spindle & is going to have a look for any decent 1&2 3&4 spindles. Unfortunately on the CR series each of the spindles are unique (throttle bodies are the same). Bit irrelevant now but In the mean time I've soldered this spindle up & it seems to be a lot smoother & is closing up nicely. 

I have used Martin at Fredmillturnparts in the past & the new linkage I bought was a quality item. I would love to have a set of his refurbished bodies with the bearings installed but just have other priorities with the funds I have at the minute.

Alan 

[roy53]

As an owner for over 40 years the main thing that we were always told is to never remove any carbon soot buildup in the bodies and butterflies.

Roy

[Jonny TR6]

18 hours ago, roy53 said:

As an owner for over 40 years the main thing that we were always told is to never remove any carbon soot buildup in the bodies and butterflies.

Roy

And for your average driver/owner that was probably good advice from Triumph. I’m sure they understood even back then that “pure” air and fuel in the combustion chamber was the best combination to maximise fuel efficiency and power output. Trouble is everything back then was a compromise and we now have a better understanding of how to adapt and improve, thanks to new products (Molykote etc), cars becoming a hobby rather than a daily driver and owners being prepared to spend money on improving their hobby.

 

Edited December 20, 2023 by Jonny TR6

[marting]

On 12/19/2023 at 5:04 PM, super6al said:

Thanks for the tip about Trzzz I messaged Carl to day & has a new 5&6 spindle & is going to have a look for any decent 1&2 3&4 spindles. Unfortunately on the CR series each of the spindles are unique (throttle bodies are the same). Bit irrelevant now but In the mean time I've soldered this spindle up & it seems to be a lot smoother & is closing up nicely. 

I have used Martin at Fredmillturnparts in the past & the new linkage I bought was a quality item. I would love to have a set of his refurbished bodies with the bearings installed but just have other priorities with the funds I have at the minute.

Alan 

Hi Alan, I have been meaning to make some stock of resale spindles for CR cars, but I have been too busy with other work. Let me know if Carl cannot sort you out and I can supply whatever CR spindles you need. 
kind regards 

Martin AKA Fred Millturn 

IMG_1220.webp

[super6al]

Hi Martin

Thanks for the message - looks like I'm sorted for now. I will get in touch sometime in the future as I will probably go for a full rebuild as per your spec with sealed bearings.

Alan 

[Jonny TR6]

PM me your details Al - there's a can of Moly waiting to find a new home. Used a bit more than I anticipated, but still plenty for you.

Throttle bodies re-installed and just looking for the missing manifold nut....

Cheers

Jonny

Edited December 23, 2023 by Jonny TR6

[BlueTR3A-5EKT]

Which manifold nut.     Manifolds To the head or exhaust to down pipe. .?    Richard Crewe Read.https://www.tr-register.co.uk/forums/index.php?/profile/10723-rcreweread/

  has silicon bronze down pipe nuts in 3/8 unc from memory at a demon price.  The ones that do not go soft or bell out when tightened, unlike brass.

Edited December 23, 2023 by BlueTR3A-5EKT

[Trumpy]

Finding this all very interesting . 
I recently bought a set of recon cp throttle bodies and replaced my old worn set . The car runs much more smoothly now but even after much fiddling and adjusting I still have to have the air bleed screw virtually shut to get tick over down . 
Molykote sounds like the answer .

[Jonny TR6]

Thanks Peter - it’s the manifold to head nut, one that holds the throttle body diamond shape thingies on. I think it’s fallen down into the vipers nest of the 6 branch manifold, or somewhere around there….

[super6al]

1 hour ago, Trumpy said:

Finding this all very interesting . 
I recently bought a set of recon cp throttle bodies and replaced my old worn set . The car runs much more smoothly now but even after much fiddling and adjusting I still have to have the air bleed screw virtually shut to get tick over down . 
Molykote sounds like the answer .

Could be but I would also check everywhere for leaks (hoses & manifold to gasket) & then ensure the throttles are balanced.

Alan

[Trumpy]

Good point , I’ve checked all obvious leak points and balanced them as much as possible . The engine rpm drops right down when the tbs are blocked off so I’m fairly sure it is the butterflies leaking air . They looked good holding them up to light before fitting . 
car runs sweetly now , certainly an improvement , just struggling with tick over .  

52 minutes ago, super6al said:

Could be but I would also check everywhere for leaks (hoses & manifold to gasket) & then ensure the throttles are balanced.

Alan

 

[Jonny TR6]

Found the missing manifold nut after jacking the car up (I hate that job !) and having a fiddle around in the exhaust manifold. Wouldn’t have seen it from above.

Bolted up the underslung throttle linkage and now have to set that up. If it’s just a case of ensuring the link rods have the butterflies just at full close, when at rest, I’m sure I can handle that, but if anyone has any tips they’d be appreciated.

A couple of days off now for festivities, so happy Christmas all and many thanks for all the help and advice as ever !

[Jonny TR6]

Got everything bolted up and the car running today. Those throttle linkages I have (ball jointed) are a pain in the ass to adjust. Couldn’t get my butterflies to close fully with them at full adjustment and having an underslung throttle linkage, I managed to get a couple of minor burns from the manifold.

Hopefully Martin (Fred Millturn) can help me out with my existing setup and his link rods.

He was also very helpful in informing me that the Molykote being a dry lubricant and alcohol based, is likely to potentially get washed off the throttle body bores. None of the articles/videos I’d seen mentioned that, but really interesting to know, especially if my tickover goes up after a few 100 miles. I’ll then know the reason.

With the link rods disconnected, the car idled at around 850rpm for the first time ever. Using my tachymeter I measured the vacuum at each throttle bore and had the following readings front to back - 2.5, 2.5, 1.2, 1.2, 2.9, 2.2. Was quite surprised to see such a vacuum, however thinking on it, with the link rods disconnected, there’s nothing to stop the cylinder vacuum pulling  the butterflies open, as the return springs aren’t super strong.

I’d be interested to hear thoughts on the range of readings from each throttle bank, could be different spring strengths, but not about to take everything off (just yet) and swap them over to test !

Edited January 1 by Jonny TR6

[PodOne]

Molykote may well get washed off from the injector side of the throttle bodies but on the outside where its only generally applied it will take a lot longer. It's a temporary fix until the carbon/crud has built up where the seal is less than perfect.

[JohnC]

On 1/2/2024 at 2:41 AM, Jonny TR6 said:

Was quite surprised to see such a vacuum, however thinking on it, with the link rods disconnected, there’s nothing to stop the cylinder vacuum pulling  the butterflies open, as the return springs aren’t super strong.

More likely simply leakage around the burretflies. It’s unlikely the cylinder vacuum will do anything as it (and the upstream air pressure) act equally on both the upper and lower semicircles of the butterflies. So that means your butterflies are not providing an equally good (or poor) seal when closed. If you’re looking for the best response when going from fully closed to open throttle, then your goal is to get those numbers as equal as possible. It’s very hard to balance butterflies *within* a pair but you may have some luck with a tiny adjustment to 3/4 to bring them closer to 1/2 and 5/6. I found that to balance within a pair I needed to use the technique Andy (I think) mentioned - snap shut when the screws are slightly loosened - and to twist the shaft slightly. But the latter was guesswork and the result may have been wishful thinking!

Hope that helps,
JC

[Jonny TR6]

Thanks JC - I'd used the snapping technique quite a bit when re-assembling to make sure they were as closed as possible. Also used the patented "pretend your looking through binoculars at a bright light" method, so think they're as close to perfect alignment with the bore as possible. It's re-assuring to know that the butterflies are equal on 3&4 and 5&6, which makes me think that I've got the butterfly alignment as close as possible.

The new linkage with ball bearings drives at some point today, so will report back with new readings once all set up and re-do the synchrometer test with the new linkage rods in place and holding the butterflies closed.

[super6al]

Hi Jonny

There will also be an amount of leakage where the butterfly fits into the slot of the spindle & the width of the butterfly is smaller than the bore of the throttle so it can fit and rotate. I'm assuming you are measuring flow not vacuum? If so I'm not sure if this amount would be enough to see unto 2.9 on your flow meter but depends on the meter scale (mine is measured in kg/h). As JC says if you can get 3/4 closer to the others I would be happy.

Alan 

Edited January 4 by super6al

[Jonny TR6]

Good points Alan re the leakage areas. I thought I was measuring vacuum with the Synchrometer ? It's the snail jobby. I'd have thought a lower reading was good if that were the case - meaning the butterflies are sealing as effectively as possible.

Mind you, this is all to achieve as good an idle as possible. I should be able to balance out the differences by opening up 3&4 once the new linkage is installed.

 

[PodOne]

Prohibitive cost but a shame you can't use 6 Synchrometer's and see instantly the effects of adjusting one pair on the other two as I suspect it would allow better results?

Andy

[Jonny TR6]

Back in the day a garage I used had a manometer tube thingy with lots of rubber pipes hanging off it.

My have a look on eBay for a laugh.