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Evening All,

A question for you induction guru's regarding the Esprit SE induction system.

General advice is often given to leave the throttle bodies/butterflies balance adjustments well alone as they are perfectly flow metered at the factory during assembly.

Once a car has covered 60k+ miles, it is likely that if you measure the flow through each choke, there will be some imbalance due to normal use.

It might not be a lot but it likely won't be perfect anymore.

Is it better to adjust for perfect balance again or is it best that the original factory settings be retained?

Cheers for your thoughts,

Andy.

Edited by AndyPG

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Having disassembled my throttle bodies as part of the engine rebuild, that’s what I’m going to have to do at some point. After removing the anti-tamper plugs, I found one screwed shut on both bodies, the other cracked open maybe half - or three quarters of a turn.


Margate Exotics.

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Thanks for the comments guys.

1 hour ago, Chillidoggy said:

After removing the anti-tamper plugs, I found one screwed shut on both bodies, the other cracked open maybe half - or three quarters of a turn.

Did you happen to notice how far the butterflies were set open on the minimum air stop screw?

I know this will vary from vehicle to vehicle but I am interested in the general position none the less.

Andy.

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Not off hand, but I have the assembly in the garage, I'll have a look later. But I think I adjusted the minimum stop screw some time ago when I was chasing an idle issue. From memory, it didn't matter where I set it, the idle did what the ECU decided anyway, presumably via the IAC valve. Someone like Dave Lisle might be better placed to advise, but in the past I remember using drill bit shanks to set minimum butterfly openings, not on the Esprit, though.

What I did learn is to balance them, measure 1 against 2, then do 3 against 4, then do the balance between the two pairs. Some kind of flow meter is required, but I haven't got that far yet. I'm intrigued to see what difference this makes, I think the screw adjustment is only really for idle performance, but I stand corrected.


Margate Exotics.

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Thanks Ian,

The minimum air stop is normally set so that the IAC valve sits between 20 and 40 counts open during warm idle at 987rpm.

I'm interested in roughly how far the butterflies are open during this condition. (ie the gap between the edge of the butterfly and the choke wall.

Cheers, Andy.

 

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I'll have to adjust that with Freescan when the engine is back in and running, so I can't help you with the butterfly openings until then. Just don't wait by the phone!


Margate Exotics.

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1 hour ago, Chillidoggy said:

What I did learn is to balance them, measure 1 against 2, then do 3 against 4, then do the balance between the two pairs. Some kind of flow meter is required, but I haven't got that far yet. I'm intrigued to see what difference this makes, I

This is totally correct , and as we discussed, it does make a difference, maybe very small , but all the little things do add up .. 

50 minutes ago, AndyPG said:

I'm interested in roughly how far the butterflies are open during this condition. (ie the gap between the edge of the butterfly and the choke wall.

They are not..   basically they fully shut .  However they never produce a full cut of ..  The stop screw should be set to just touch when they are fully closed , This will prevent the return springs making the BAV have a forced contact with the TB its self..   In the past i have seen TB's with marks from the BAV in the TB inner wall , at the contact points.. 

 You will always find one balance screw on each TB fully shut , the other cracked to balance the inconsistency in assembly..  Once you have disassembled them this original setting go out the window..      Also you will find over time even with the filtered air that passes through the bleed hole past the adjustment screw , it still gets a deposit which will change the flow characteristics..   This is normal and found in just about every TB set up I check..   

13 hours ago, AndyPG said:

General advice is often given to leave the throttle bodies/butterflies balance adjustments well alone as they are perfectly flow metered at the factory during assembly.

This is true when the cars were new and being serviced by the dealers...   Rest assured any post tuning that will have been done would of included checking the individual balance criteria.. The anti tamper screws will have been removed and replaced if adjustment was needed..   Now these cars have so many years and miles on , it would be prudent to check , This is done with a throttle flow meter , which is a very simple process to do ..    Once you have balanced and set the whole system you should have tick over controlled by the ECU via the IAC valve .  If this tick over is to low , I would first check the IAC function , if all is ok then any micro adjustment can be made via the stop screw or the by pass balance screws ..  It is very rare to need any micro adjustment if everything is working as it should.  However , most of these cars are circa 30 years old and still feature original injectors , which have never been cleaned or replaced, along with other ignition parts like the coil packs .. All of these over time deteriorate , so having a micro adjustment facility can be useful.. to compensate.  

I must stress that you need to be aware of what you are doing and if unsure consult a reputable dyno technician to do final set up,  then do a power test to clarify all functions are performing correctly..     A power run is the only way to insure your ECU is calibrating the engines functions correctly ie. secondary injectors coming in on time , The TPS function is calibrated within range ETC ETC,,    So if unsure  just Ask someone .  !!! 

 

Synchrometer Flow Meter - International Tool Company
 
A useful bit of kit to have 
 

 

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1 hour ago, CHANGES said:

They are not..   basically they fully shut .  However they never produce a full cut of ..  The stop screw should be set to just touch when they are fully closed

Thanks Dave, this was the info I was looking for.

Completely agree with your recommendation on those STE synchrometers.

I have had one for a while and they are superb.

Andy.

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On 15/05/2020 at 17:40, AndyPG said:

Thanks Dave, this was the info I was looking for.

Completely agree with your recommendation on those STE synchrometers.

I have had one for a while and they are superb.

Andy.

924264685_Screenshot2020-06-08at9_47_24AM.png.e233c85b8301371996fb3e07d79c13ab.png

Has anyone here used the Carbtune Pro balancers before. I bought a set, but even with the throttle plate almost completely closed, it was almost impossible to get any reading.

What I am saying is that it looks like there isn't sufficient vacuum to produce any type of meaningful reading. Eventually, I had to revert to an STE flow meter.

Carbs have been professionally rebuilt by a specialist, and the engine idles and runs nicely so I don't there is an issue with the carburettors.

Edited by ekwan

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56 minutes ago, jonwat said:

I always balanced mine using a carbtune, never had any problems. :thumbup:

Did you have the line restrictor installed? That's the supplied little transparent tube with the 1mm hole, supposed for damping out oscillations.

Edited by ekwan

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6 hours ago, ekwan said:

it looks like there isn't sufficient vacuum to produce any type of meaningful reading

Devices like the Carbtune Pro need to be connected to drilled tappings down stream of the butterflies in order to work.

Offering the pipes to the intake upstream of the butterfly won't produce a usable reading.

Some vehicles have suitable tappings pre-installed otherwise provision would need creating.

The STE device simply pushes against the intake and IMO the way to go with the Esprit SE.

Andy.

 

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54 minutes ago, ekwan said:

Did you have the line restrictor installed? That's the supplied little transparent tube with the 1mm hole, supposed for damping out oscillations.

Was long time ago but I don't remember any restricters, just rubber hoses. :unsure:

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Cheers,

John W

http://jonwatkins.co.uk

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4 hours ago, AndyPG said:

Devices like the Carbtune Pro need to be connected to drilled tappings down stream of the butterflies in order to work.

Offering the pipes to the intake upstream of the butterfly won't produce a usable reading.

Vacuum ports of the DHLA carburettors.

 

Edited by ekwan
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6 hours ago, ekwan said:

Vacuum ports of the DHLA carburettors.

Sorry, wasn't quite clear in your post. Can't see any reason why you wouldn't get a good reading if the Carbtune is connected to a live vacuum tapping.

The STE flow meter is well worth a look. Pretty bomb proof method and the needle is nicely damped so there's no pulsing.

16 hours ago, ekwan said:

the engine idles and runs nicely so I don't there is an issue

You would be surprised how out of balance these carbs can be when not checked running.

Well worth adjusting them for perfect balance IMO even if it seems ok.

Have a listen to each choke, in quick succession,  with a piece of hose pipe while the engine is idling. The difference in the induction hiss quite noticeable between chokes when the balance isn't quite right.

Andy.

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6 hours ago, AndyPG said:

Sorry, wasn't quite clear in your post. Can't see any reason why you wouldn't get a good reading if the Carbtune is connected to a live vacuum tapping.

The STE flow meter is well worth a look. Pretty bomb proof method and the needle is nicely damped so there's no pulsing.

 

That's what I was wondering, why I didn't get a reading from the Carbtune, but now I suspect it's because I was using the supplied restrictors, solely for the purpose of damping any reading fluctuations. Now I'm left with an expensive toy. Duh!

I did use an STE in the end and that's how I got the engine running properly. Case Closed! 

Edited by ekwan

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4 hours ago, ekwan said:

Now I'm left with an expensive toy.

Ebay?............

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5 hours ago, ekwan said:

That's what I was wondering, why I didn't get a reading from the Carbtune, but now I suspect it's because I was using the supplied restrictors, solely for the purpose of damping any reading fluctuations. Now I'm left with an expensive toy. Duh!

Loads of people on here have used the Morgan Carbtune to balance their carbs including bikers (with far smaller engines) which is their primary market, I suspect the error was in something you were doing. :unsure:


Cheers,

John W

http://jonwatkins.co.uk

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6 minutes ago, jonwat said:

Loads of people on here have used the Morgan Carbtune to balance their carbs including bikers (with far smaller engines) which is their primary market, I suspect the error was in something you were doing. :unsure:

With hindsight, yes indeed. Probably those restrictors were the issue.

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