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New car - rough running


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Hi all,

 

Took the TR6 (CR) out for another run today (well the sun was out!) with a view to taking a look a the rough running. As before she runs fine over about 2000rpm but below and at tick over it is rather lumpy. I know I am not the first to experience this as there are a number of posts around on this subject. Tomorrow when the engine is cold I will check the valve clearances and the static timing but for now i have found the following....

 

With the airbox off I covered the airfeed hose expecting (if things were normal) for the engine to stop, in reality it did not and if anything it ran a little better

 

I put vacuum gauge (a basic Gunson version) on each of the throttle bodies in turn on tick over and got these readings (0-5 on the gauge) for each cylinder:

  • 1 = 0
  • 2 = 1
  • 3 = 5
  • 4 = 5
  • 5 = 0
  • 6 = 0

So, I deduce from this that i need to sort the butterflies out in the middle pair - I feel some bedtime Haynes reading....

 

What I would like to check though is how far the butterflies should open on full throttle. Here is a picture of mine, Should they be horizontal when open fully?

 

Words of wisdom most welcome from those with experience and tell me if i am going down the wrong path!

 

Many thanks

 

Paul.

 

 

post-15512-0-54771600-1523742247_thumb.jpg

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The numbers don't mean anything to me. The colourful side of the Gunson gauge should read ins Hg which is the conventional unit of measurement for old engines. If the above measurements are in in Hg then you have gross leakage .Note the higher the vacuum the better the butterfly closure.

 

I measure my engine vacuum at the brake booster connection with everything on the manifold connected. I have a somewhat lumpy tick over with a TR5 cam , my operating settings are around 10"Hg at 800 rpm.

 

From memory my butterflies don't open fully either with the standard linkage, there are aftermarket linkage kits to correct this but won't affect your idle.

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Paul,

Since you have 6 individual readings/measurements, where did you take them?

Each TB has only one connection on top.

Regards,

Waldi

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You want about 2-3 ins hg on each throttle. You’ve got nothing going through 1/5/6 .... next to nothing through 2. Hence the poor idle.

Disconnect the throttle cable and the choke cable.

Put a straight edge across the brass openings and check first that all 3 throttle bodies are perfectly level. Looking at your photo going by the short balance hose it looks like the aft pair is not level with the centre pair.

Then get the centre pair fully closed and adjust the forward and aft pair screws to get them fully shut.

Connect the throttle cable and using its adjuster get the centre pair just cracked open so a 0.002-.004 feeler guage is a sliding fit.

Adjust the other two pairs to get the same.

Set the air bleed adjuster about half way.

Start the engine and see what it revs like. You will have to play with the adjusters to get the balance right.

There is an adjuster bolt on the throttle pedal for max opening of the Butterflies!

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Thanks for e responses, appreciated. I think I may have misled you with my poor terminology. When I said vacuum gauge this is just a Gunson Carbalancer which I push onto each of the throttle bodies in turn, hence 6 readings. The numbers have no direct meaning as such in terms if inches hg but are just relative to each other to show more air is getting sucked in compared to others. DaveN - will follow your instructions later but was working on the basis that at tick over no air should be going through the throttle bodies and all through the air valve - hence blocking air valve should stop the engine; is that not the the case then?

Thanks.

Edited by NevTR6
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Hi , Nev i presume?

 

Balancing the throttle bodies is very worthwhile, if a bit fiddly.

You may want to replace the linkages and bushes to get better adjustability and reliability.

Also you might want to check the injectors are spaying evenly, a reconditioned set are not expensive and commonly needed.

 

Whereabouts are you ?

 

Steve

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First step should be to get those centre butterflies closing properly. Your "Carbalancer" is a plastic cheapo version of older kit, such as the Crypton SynchroCheck, UniSyn or Synchrometer (all QV), all easier to use, IMHO. New examples of the last on sale on eBay.

And it has given you the clue of excess intake at idle on the middle throttle body.

 

The instructions for adjustment are in the Brown Bible (Starting page 19.20.05) but as they occupy six pages I humbly suggest you get yourself a copy ( It will be the best investment you can make for the future of your TR!

 

A quick check is to use a feeler gauge above and below the butterflies when closed. Quote, "a 2 thou ... should not pass between the plate and the bore"

Here's the page - there are five more on butterflies!

 

John

post-535-0-71906800-1523785108_thumb.jpg

Edited by john.r.davies
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@John. Yes correct you should not be able to pass a feeler under the ‘butterfly’. My bad! I was thinking that they shouldn’ slam fully closed and wear the body!

I drive mine like it hasn’t got any butterfly plates to get in the way!

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And the butterflies should be horizontal at full throttle. You will need to disconnect all of the linkages then take one and adjust it so that you get full opening on that TB. Then repeat for the other TBs.

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Hhhmmm. In a matter of interest. I’ve just been out and whipped the air box off to have a looksee at mine. I can just... with a wriggle force a 0.0015in feeler under each of the TB’s..the air valve isn’t fully closed either. It idles at just under the 800 mark

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Hhhmmm. In a matter of interest. I’ve just been out and whipped the air box off to have a looksee at mine. I can just... with a wriggle force a 0.0015in feeler under each of the TB’s..the air valve isn’t fully closed either. It idles at just under the 800 mark

Thats pretty much perfect then, butterflies shouldnt close hard on the body as it will cause wear.

Stuart.

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Hi Paul.

 

This is the procedure I use and it works (CR only). The air flow meter is available off eBay and worth every cent!

 

https://www.ebay.com/itm/Carburettor-Carb-Syncrometer-Syncro-SK-Balancer-Weber-Dellorto-40-45-DCOE-ADV/263602834376?hash=item3d5ff40bc8:g:utkAAOSwjXNaW3~j&vxp=mtr

 

1. Check that the butterflies are fully opening and adjust as necessary to achieve this (mine were only 50-60% open at full throttle - I had to shorten the pedal stop screw to get the necessary extra travel).

2. Check that there is a small amount of slack in the throttle cable (inner).

3. Make sure that the choke & MU enricher both go fully home and adjust the choke screw to get a small (say 0.5mm) of clearance between the head of the adjuster screw and the cam (note: I slotted the top end of the choke screw to make it easier to adjust once the locking screw was loosened).

3. Warm the engine and set the idle to 800rpm with the idle air bleed screw . Stop the engine then recheck that the throttlecable still has some slack.

4. Loosen the locknut on the vertical throttle link and adjust so that there is a small amount of free-play (leave the locknut loose at this stage).

5. Starts the engine again and with an flow meter in either intakes 3 or 4, rotate the choke adjuster screw (really a small domed hex-head bolt) in or out as necessary to get an airflow reading of 3. Check the second intake of the pair and adjust the screw to get an average reading if necessary. Adjust the air bleed screw to get the rpm back to 800 if needed whilst doing this and once done nip up the locknut.

6. Move the airflow meter to either of intakes 1 or 2 and adjust the spring-loaded screw between 2 & 3 to get an average flow meter reading of 3 as above.

7. Move the airflow meter to either of intakes 5 or 6 and adjust as above using the spring-loaded screw between 4 & 5.

8. Recheck all, but I found no change had occurred.

9. Adjust the air metering screw one last time if necessary to set the correct hot idle. If there is no adjustment left (i.e. it is now fully closed and the idle is still high), repeat the steps 5 - 7 with a slightly lower flow setting of say 2.5. If that still doesn't work then it is likely you have a vacuum leak which will need to be investigated.

9. Adjust the throttle link rod to leave a small amount of play (say 1.0-1.5mm) and tighten the locknut.

10. Allow the engine to cool and recheck that there is still a small mount of play in both the throttle cable and the throttle link rod.

post-14246-0-54098100-1489046700_thumb.j post-14246-0-66074300-1489046727_thumb.j post-14246-0-50429100-1489046989_thumb.j

Gavin

NZ

Edit: I have marked the two linkage adjuster screws with white paint on the screw head and immediately adjacent on the linkage so that I can check for any movement of the screws.

Edited by KiwiTR6
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Thanks everyone for your time and input, it is all very much appreciated.

 

I managed to spend some limited time in the garage Sunday and found that on a couple of the butterflies there was a slight gap at the top or the bottom (using the cigarette paper approach) so attempted to undo the two screws on those affected to try and re-seat them. However, these were very tight and it appeared i was more likely to ruin the head rather than remove the screw so stopped.

 

Gavin, thanks for your step by step instructions. I plan to follow those when i next get the opportunity, unfortunately due to a change in circumstances that wont be for a couple of weeks. Strangely i did wonder if there was a stop on the pedal and so have adjusted that as well to give more movement to the butterflies.

 

Pete - I am on the look out for a brown bible (I have one for the Spit so know how useful they are) and thanks for posting the image.

 

Finally, I have noted not only the breadth of advice so far but the distance; Australia, Netherlands, Ireland, Australia and the UK - most impressive :-)

 

Thanks.

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And don't forget NZ, there's a lot of keen. resourceful TR6 owners down there- like Gavin.

 

Thanks Mike.

 

Confusing Kiwis for Aussies is understandable and very common, so this video clip is quite helpful in identifying the essential differences between us (Warning: Kiwi humour - no offence meant to our Aussie cousins!)

 

www.youtube.com/watch?v=f2gii2nenUg

 

Edit: You'll need to cut and paste this to view - for some reason I couldn't attach the actual link :)

Edited by KiwiTR6
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The clip didn't attach. But in a similar vein , I note how in some places people with strong Scotch and Welsh accents are believed to have come from England.

I copied the (unhighlighted) www address and later pasted it into the Google 'search' box and the video played OK.

About to have a look. Suspect it will drain a bit of urine out of the Aussies.

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I copied the (unhighlighted) www address and later pasted it into the Google 'search' box and the video played OK.

About to have a look. Suspect it will drain a bit of urine out of the Aussies.

Accent wise the Kiwis say 'lttle pg'*, and they think we say 'leetle peeg'*. (*English = "little pig".)

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I copied the (unhighlighted) www address and later pasted it into the Google 'search' box and the video played OK.

About to have a look. Suspect it will drain a bit of urine out of the Aussies.

We are use to it. They are like little brothers trying to get one up on big brother, who they love really. :-).

When it has come to the crunch, the ANZACs come together.

I just wish they had decided to join the Australian Federation so we could field a decent rugby team.

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  • 2 weeks later...

Hi all.

Now I have had the opportunity to get back to the car I just wanted to report on the outcome. Having followed Gavins advice the car is now idiling much better and moving through stop / start traffic is more relaxing. I will try and fettle a little more but pleased with where we have got to. Hopefully the sun will come out again and I can do some more test runs but at least I know he heater is working...

Finally, as some of you spotted, the car was indeed ex TRGB and I have to say I have been impressed and very pleased with their service (thanks guys). No personal connection etc etc just a happy customer.

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Accent wise the Kiwis say 'lttle pg'*, and they think we say 'leetle peeg'*. (*English = "little pig".)

 

I have a very good customer who is married to a lovely Australian girl, first name Vicky. I, being a Kiwi, would pronounce her name as "Vik-E" whereas she pronounces it on her answerphone as "Vee-Key". Quite a noticeable difference and perhaps related to the part of Australia that she hails from.

Edited by KiwiTR6
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