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harrogateTR6

Setting up throttle butterflies TR6 Pi CP

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I know there have been a few threads about this, but guys Im desperate!

 

I have a 1973 car which was brought back from the USA in the 90's and was converted to PI with a donor engine from a 1971 CP car. Ive owned it for the last 17 years, with hardly any issues- superb tick over, good responsive acceleration.

 

Last year it was beginning to run a bit lumpy bottom end on acceleration, so I took it to a rolling road. All was going well, until the mechanic started playing with the throttles, and sprayed carb cleaner on the butterflies. Then he commented that he couldnt adjust one of the sets of butterflies as the slotted end of the throttle rod was damaged. Anyway at the end of it I had a once perfectly ticking over car, ticking over at 1300rpm. I wasnt happy, but he said it would calm down with use. It didnt.

 

I realised having read on here that cleaning them is a big mistake.

 

I also realised that the broken throttle rod needed replacing. I then realised that the exact replacement of the original was not available from Rimmer or Moss.

 

I did some research and ended up buying some ball jointed type rods from Revington TR, these seemed like the sensible option. I bought myself a syncrometer and fitted the rods. I did manage to get the butterflies reasonably synced, but as soon as the car got really hot, the throttle would start to stick. Many calls to revington (who were super helpful) but nothing seemed to sort the sticking throttle. As soon as the rods got hot- just too much friction! I even tried beefier springs on the throttle return, but it spoiled the control and still wouldnt stop the sticking issue. I also noticed that with the the ball and socket design the whole linkage could move laterally- not good.

 

Ive ditched those and found some exact copies of the originals supplied by TR GB. These have instantly cured the sticking throttle, but I just cannot get the butterflies syncing.

 

With the butterflies fully closed the car is ticking over with the airbleed screw fully closed. The hoses are all new and snug.

 

If i use the cigarette paper method to set the butterfly gap, starting on cylinders 5/6 then working to 3/4 the 1/2 the car ticks over at 2000rpm and they dont seem very well synced. I notice that the design of this thing is flawed, because as soon as you get one right, then move on to the next, by adjusting the next it throws out the first. They dont work that independently- its a bloody nightmare!

 

Ive used the synchrometer/ weber tool method too and have managed to get cylinders 6, 3 and 1 (as per the manual) all giving the same reading at 1500 rpm, but when I drop the revs down, the thing is practically stalling when increase the throttle, horrible throttle response. It makes no sense at all.

 

I have noticed that each set is giving slightly different readings on the syncrometer, most noticeable on 3/4 where at the lowest readings im getting 11/2 on cylinder 3 and 3 on cylinder 4. These discrepancies cant be helping!

 

The other thing Im noticing is that if I build the revs slowly and then back off the throttle completely, its taking a long time for the revs to come down, unless I blip the throttle.

 

Im getting very frustrated with this and im unsure what to do next. Am i doing something blatantly wrong, or do all my throttle bodies need rebuilding??

 

The workshop manual procedure is about tweaking an existing set up, but when you are putting in new rods its like starting from scratch.

 

I know the whole thing is flawed, so maybe an overhead linkage might be the best option and it will get those rods away from the searing heat of the exhaust?

 

if anyone can help, I would be sooooo grateful.

 

Thanks in advance.

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Sounds like your mechanic friend may have bent the throttle spindles being overly ham-fisted.

The ball-socket after market fittings are more than an improvement over the originals so any sticking would probably be associated with the radial arc movement being off centre of the spindle arms causing the ball-socket to bind. With the other TB's disconnected does each spindle snap shut cleanly and without sticking? If they do then look at the up/down side/side of the arm and the rod as it should not move side to side (hope that description makes sense)

For my money..either a new set of spindles or reconditioned bodies sounds like the go. I'd also use the ball ends over the originals as eventually the originals will wear the hole in the spindle arm oval making the balancing virtually impossible.

Other than that..you are doing what I would do..set the idle to ~1200-1500 rpm and using the sync snail, set all to the same flow rates (do this with the air bleed closed as well). Once set, adjust till just off stalling then crack the air bleed to give the idle speed you want.

 

Oh and I would check ALL the butterflies not just 1,3 &6 as you can twist the spindle if you are overly forceful with them (they are softish brass) causing one to butterfly to seat whilst the other is way off.

 

Hope it helps

 

Andrew

Edited by AndrewP

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Sounds like something is out of line, causing binding.

 

As Andrew says the ball jointed links are excellent, i fitted them last year as i too had a broken original and the difference is marked.

 

There is a 'special tool' for aligning the three sets of throttle bodies, someone in your local group may have one to lend?

 

Steve

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I started my adjustments with one of these http://www.ebay.co.uk/itm/Triumph-2-5PI-TR5-6-Lucas-Injection-Throttle-Body-Alignment-Tool-NEW-/132239081301?hash=item1eca103f55:g:37cAAOSwIjJZT8KRthat gave me a fixed alignment position to start from, and return to before starting to adjust.

 

Alan

Edited by barkerwilliams

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I would first of all reset the throttle discs to the throttle shaft to throttle body, take off the links, loosen the 4 screws in each body and snap the throttle shaft closed, this should align the plate with the hole better, then tighten the 4 screws, its easier to do this with the throttle bodies off, but can be done. If off the car you shouldn't be able to see light thru when the plate is closed..

The trouble I had with mine was that the 2,4 and 6 would be letting in much more air, this has now been rectified but applying some Rocal product.

You will have a problem with the ball jointed links, they will be right with the synchroniser but when you try and tighten up the links everything will change, but can be done with some patience!

Also make sure you have the one stop bolt in the middle, by the throttle cable, and also make sure the 3 plastic bearings that the operating shaft run thru are a good fit, any slack here will upset everything.

It takes time to do but its worth it in the end!

A straight edge across all the body inlets will do the same thing as the tool above.

John

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Thanks so much for the responses, I can see me having all the throttle bodies refurbished and purchasing a new overhead throttle mechanism!!

 

I had another go today, I used the workshop manual method, eyeing up where the welded washer is just about to touch the trunnion on cylinder 6, I had the other rods disconnected and then did a similar thing with them. I then used the synchrometer and I got them syncing sweet, with a really nice pick up. BUT THEN, just like before as soon as I reconnect the throttle cable and put the everything back together and drive the car off the drive, repeat of throttle sticking and the car is bellowing at 3000rpm. Im totally confused as to why this happens. Even if i completely slacken off the accelerator cable, the butterflies are not springing back to where i set them- I have to push the levers which connect to the spindles back toward the throttle bodies to get the revs back down. Im flummoxed.

 

I havent had the throttle bodies off the car so Im trying to work out what benefit the alignment tool would be- isn't this for reassembling the bodies back to the cylinder head? Do you need it if reattaching the linkage to the cylinder head- as I have had this off, to fit the new bushes. Could this be the problem?

 

 

On thing I have noticed - is that the whole shaft slides about 1/2 inch from one side to the other. I have replaced the nylon bushes, with new ones, so these are tight, but dont stop any lateral movement. John you mention a stop bolt in the middle- I havent seen this?

 

I will try and reset the throttle discs and see if this helps- as there are definite imbalances, but this doesnt explain the sticking throttle?

 

I think there is a limit to how much longer my neighbours will endure the torture of me trying to set this up! My sanity is on the brink as well.

 

I dont really know where to take the car if I use a garage, as I cant drive it, and it seems like quite a specialist job. I am in Yorkshire if you have any recommendations!

 

Many thanks

 

Roland

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Sounds like your mechanic friend may have bent the throttle spindles being overly ham-fisted.

The ball-socket after market fittings are more than an improvement over the originals so any sticking would probably be associated with the radial arc movement being off centre of the spindle arms causing the ball-socket to bind. With the other TB's disconnected does each spindle snap shut cleanly and without sticking? If they do then look at the up/down side/side of the arm and the rod as it should not move side to side (hope that description makes sense)

For my money..either a new set of spindles or reconditioned bodies sounds like the go. I'd also use the ball ends over the originals as eventually the originals will wear the hole in the spindle arm oval making the balancing virtually impossible.

Other than that..you are doing what I would do..set the idle to ~1200-1500 rpm and using the sync snail, set all to the same flow rates (do this with the air bleed closed as well). Once set, adjust till just off stalling then crack the air bleed to give the idle speed you want.

 

Oh and I would check ALL the butterflies not just 1,3 &6 as you can twist the spindle if you are overly forceful with them (they are softish brass) causing one to butterfly to seat whilst the other is way off.

 

Hope it helps

 

Andrew

Hi Andrew, Thanks for your advice. As the spindle controls both butterflies, Im confused as to how you can twist them, unless the they are really badly aligned in the first place. The spindles all snap shut nicely when the rods aren't connected. One thing I have noticed is that the rods can move side to side about 1/4 inch as a result of the whole bottom linkage being able to move side to side? Thanks Roland

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I would first of all reset the throttle discs to the throttle shaft to throttle body, take off the links, loosen the 4 screws in each body and snap the throttle shaft closed, this should align the plate with the hole better, then tighten the 4 screws, its easier to do this with the throttle bodies off, but can be done. If off the car you shouldn't be able to see light thru when the plate is closed..

The trouble I had with mine was that the 2,4 and 6 would be letting in much more air, this has now been rectified but applying some Rocal product.

You will have a problem with the ball jointed links, they will be right with the synchroniser but when you try and tighten up the links everything will change, but can be done with some patience!

Also make sure you have the one stop bolt in the middle, by the throttle cable, and also make sure the 3 plastic bearings that the operating shaft run thru are a good fit, any slack here will upset everything.

It takes time to do but its worth it in the end!

A straight edge across all the body inlets will do the same thing as the tool above.

John

Hi John, Whats the stop bolt in the middle where the accelerator cable attaches? Also do you need the alignment tool for attaching the linkage if its been off? thanks

 

Roland

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I understand why I need the alignment too now folks, I think thats my problem, the brackets arent alligned properly so that when I set everything up, it soon goes out of sync and the sticking throttle would be because the main spindle isnt aligned... doh. I will let you know how I get on from here. :rolleyes:

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The bushes are running dry, do you have the correct return springs fitted?

I have the correct springs but even these needed modifying a bit. Bushes are well greased.

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The stop screw is pn 63, you said you had a CP setup.

You should be able to eliminate the side movement of the throttle shaft by adjusting the righthand bracket. pn 58 mine has slotted holes

http://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/fuel-system-induction-controls/engine-controls/accelerator-pedals-control-cables.html

John

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The alignment tool referred to earlier, can this not be done by placing a straight edge across the tops of the six inlet pipes.

I assume that is its purpose to Align all three throttle bodies.

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The stop screw is pn 63, you said you had a CP setup.

You should be able to eliminate the side movement of the throttle shaft by adjusting the righthand bracket. pn 58 mine has slotted holes

http://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/fuel-system-induction-controls/engine-controls/accelerator-pedals-control-cables.html

John

Hi John, I do have that screw, but isnt it just an idle adjustment screw. Ive acquired it recently as my car didnt have one fitted and ran fine for years! Ive sussed that I can bring in the slack with the both the end brackets now - thanks to you folks! That will eliminate that movement, but I also need to align them with a straight edge- not so easy where the throttle is?

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Hi Andrew, Thanks for your advice. As the spindle controls both butterflies, Im confused as to how you can twist them, unless the they are really badly aligned in the first place.

Hi Roland. Easier to see when they are apart but the brass spindle is slotted to allow the butterflies to slide through the spindle. Too much force on one of the butterflies or the input end can cause either or both butterflies to get out of sync by twisting the spindle.

Reading some if your latest posts clarifies a few things in that you can get it to idle but it's just not returning cleanly to idle.

I'm assuming that if you manually move the linkage closed, it sits back nicely at ~900 rpm or so until you blip the throttle again?

As others have said, it might be a bit of fiddling to get the bracketry for the throttle linkage all lined up as if those bushes at either end or the middle of the rod bind, then this will cause exactly the symptoms you have described.

 

If you haven't moved the TB's then no need to buy the jig (lot of $$) and a straight edge across the top of the TB's will just verify that they are aligned.

Edited by AndrewP

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Hi Roland. Easier to see when they are apart but the brass spindle is slotted to allow the butterflies to slide through the spindle. Too much force on one of the butterflies or the input end can cause either or both butterflies to get out of sync by twisting the spindle.

Reading some if your latest posts clarifies a few things in that you can get it to idle but it's just not returning cleanly to idle.

I'm assuming that if you manually move the linkage closed, it sits back nicely at ~900 rpm or so until you blip the throttle again?

As others have said, it might be a bit of fiddling to get the bracketry for the throttle linkage all lined up as if those bushes at either end or the middle of the rod bind, then this will cause exactly the symptoms you have described.

 

If you haven't moved the TB's then no need to buy the jig (lot of $$) and a straight edge across the top of the TB's will just verify that they are aligned.

Hi Andrew. You describe exactly what is happening. Today I have set the car up again, got the linkage working really sweet, very little play by carefully adjusting the brackets, have greased the points where the main spindle goes through the bushes. The throttles butterflies are well synced, but as soon as it all gets hot and I take it out on the road- same old problem, idling revs of 2-3000rpm, only returning to normal if I give the throttle a good blip. Maybe its the new bushes and it may improve as they wear a bit, Ive no idea. The only other way of getting the revs to return is to push down the lever which controls the 5/6 throttles, back against the throttle body, it moves another 1-2 mm from its resting position. If I nudge the throttle pedal up with my foot it kills a few hundred revs too, so Im wondering if I need a stronger return spring on the pedal?

 

Part of the problem I have is that the car is ticking over at 1000rpm with none of the throttle linkages attached and the air bleed shut, so the butterflies are just not sealing shut- ever! Its infuriating.

 

Im not stripping it all down again, I just know that it will do exactly the same thing. Maybe driving it a bit will improve things. I saw another thread where someone had sprayed molykote onto the throttles and that had improved the seal- maybe worth a try. I am resigning myself to having the bodies stripped and refurbished and slinging the current linkage for a new overhhead one. :wacko:

 

Thanks for all your help and to everyone else.

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When I looked at my throttle bodies like through a binocular to day light I could see differences in the gap pattern (moon shapes) on some.

I had one shaft (spindle) with too much play ( 0.30-0.40 mm) and also some hard carbon deposits near the area where the butterfly seats.

The TB wirh the worn shaft did not fully close.

Will order a new shaft and see how that improves things. And have removed the hard deposits, that helped too.

Waldi

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Roland

I live in Leeds and have a throttle body alignment jig you can borrow if you want. I've never actually used it myself. Your problem does sound like worn throttle bodies.

Matthew Sykes runs a small workshop in Leeds and has done good work on my TR6 before (MKS classics). I can recommend him very highly if you need help.

David

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Hi Andrew. You describe exactly what is happening. Today I have set the car up again, got the linkage working really sweet, very little play by carefully adjusting the brackets, have greased the points where the main spindle goes through the bushes. The throttles butterflies are well synced, but as soon as it all gets hot and I take it out on the road- same old problem, idling revs of 2-3000rpm, only returning to normal if I give the throttle a good blip.

So, it all seems sweet when cold but goes to pot when the engine warms up, right?

 

With the engine cold and throttle good, if you *gently* press in turn each of the plates on the three spindles, does the tickover fall very much if at all? I'm guessing not. Now, with the engine hot, set the revs and gently release the throttle. The revs stay high, right? Repeat pressing the little plates, only this time gently and *carefully* as it's H - O - T hot down there! Do the revs fall when you press one or more of the spindles? <Re-reading post #7 this is what happens> How many of the spindles do you need to push? All of them? Does each one reduce the revs a bit until you get to sensible or does one make the most difference?

 

So, pushing the plates cold - nothing, hot - drops the revs? I think it's fairly conclusive proof that that spindle is sticking - presumably due to the now hot components of that manifold. I suppose it could still be the linkage but as it's not so subject to the heat of the head it seems much less likely.

 

I suppose there is one other possibility - that the spindles have suddenly worn ovals in the body and that they settle with the "leak" downstream of the butterfly when hot. I don't know about PI but I've had this on carbs. It seems unlikely that this could happen suddenly ... <thinks> ... but perhaps if the ovals were full of crud and your well-meaning mechanic used carb cleaner ... ?

 

I've had mine refurbed with the bearing adaption from one of the usual suspects - he only puts a bearing at the spring/lever end as the other isn't subject to sideways forces - and it cured the sticky throttle I had. It was no where near as bad as yours!

 

Cheers, Richard

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So, it all seems sweet when cold but goes to pot when the engine warms up, right?

 

With the engine cold and throttle good, if you *gently* press in turn each of the plates on the three spindles, does the tickover fall very much if at all? I'm guessing not. Now, with the engine hot, set the revs and gently release the throttle. The revs stay high, right? Repeat pressing the little plates, only this time gently and *carefully* as it's H - O - T hot down there! Do the revs fall when you press one or more of the spindles? <Re-reading post #7 this is what happens> How many of the spindles do you need to push? All of them? Does each one reduce the revs a bit until you get to sensible or does one make the most difference?

 

So, pushing the plates cold - nothing, hot - drops the revs? I think it's fairly conclusive proof that that spindle is sticking - presumably due to the now hot components of that manifold. I suppose it could still be the linkage but as it's not so subject to the heat of the head it seems much less likely.

 

I suppose there is one other possibility - that the spindles have suddenly worn ovals in the body and that they settle with the "leak" downstream of the butterfly when hot. I don't know about PI but I've had this on carbs. It seems unlikely that this could happen suddenly ... <thinks> ... but perhaps if the ovals were full of crud and your well-meaning mechanic used carb cleaner ... ?

 

I've had mine refurbed with the bearing adaption from one of the usual suspects - he only puts a bearing at the spring/lever end as the other isn't subject to sideways forces - and it cured the sticky throttle I had. It was no where near as bad as yours!

 

Cheers, Richard

Hi Richard, you hit the nail on the head.

 

I set the rods up as per the manual, so the brazed on washer in the rod for 5/6 is just touching the trunnion. If you adjust it more you can see it pushing up the lever/plate - so I take it back down to the point where there is no movement of the throttle plate. This would now be the method I would use if I was using the ball and socket type adjusters. I do this with the other throttle rods disconnected, so that they have no interference. I then do the same with them and I have discovered that doing it visually is better than using a meter. I think the meter only gives reliable results if you have a perfect set up.

 

As you say everything is sweet until everything gets really hot, where upon it gets worse. I can identify the culprit as 5/6 and cylinders as this is the plate/ lever that if I push down from above against the throttle body ( i have asbestos fingers :blink: ) returns the rpm to normal, so it would appear that I have a sticking throttle on body 5/6? The others seem ok.

 

I would imagine refurbishing is a highly specialised job: its not something Im mad keen to do myself- I'm not an engineer (as you can probably tell :lol: ). I have contacted prestige, but Malcom is in Wrexham and Im in Harrogate, so a small logistic issue. A car trailer may need to be hired as I dont fancy the non optional cruise control I currently have driving across the M62!!

 

Thanks, Roland

Edited by harrogateTR6

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Roland

I live in Leeds and have a throttle body alignment jig you can borrow if you want. I've never actually used it myself. Your problem does sound like worn throttle bodies.

Matthew Sykes runs a small workshop in Leeds and has done good work on my TR6 before (MKS classics). I can recommend him very highly if you need help.

David

Hi David

 

Good to hear from someone local to me. :)

 

Thank you for offering to lend the alignment tool, If I choose to take the throttle bodies off, I would think I would need one. so good to know I could borrow one from you as opposed to buying one for £65 and then having it hang on my garage wall doing nothing! I aligned the brackets with a straight edge.

 

Thank you for recommending Mathew Sykes too, I hadnt of him. I must admit Ive struggled to find a specialist, in recent years - as they have all retired! I used to use wharfedale TR in Wakefield. I have a number of classic car garages nearby, but Im not sure about their expertise when it comes to this sort of thing. The PI system is a law unto itself isnt it? Is this the sort of job Mathew would take on?

 

Thanks

 

Roland

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Guest ntc

I have the correct springs but even these needed modifying a bit. Bushes are well greased.

You also should sync at 800 rpm.

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Roland,

when you say greased, I assume you mean oiled?

Grease could result in some sticking especially with butterflies closed where springload is lowest.

 

Not trying to be the "wise guy", it may be my lack of English.

Regards,

Waldi

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I would imagine refurbishing is a highly specialised job: its not something Im mad keen to do myself- I'm not an engineer (as you can probably tell :lol: ). I have contacted prestige, but Malcom is in Wrexham and Im in Harrogate, so a small logistic issue. A car trailer may need to be hired as I dont fancy the non optional cruise control I currently have driving across the M62!!

 

Thanks, Roland

 

Roland, yes Prestige did mine. I seem to recall (it's a few years ago) that he sent through refurbed manifolds before mine went back to him. That way, you only have to find someone locally to do - or help you with - the job. Have a chat with Malcom, he's very helpful.

 

Cheers, Richard

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