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Help wanted -(wish I had never started to upgrade / change parts).

 

I have just recently upgraded some fuel injection gear and exhaust system, and now I have poor performance / misbehaving engine (My TR6 is a 1973 manufacture).

 

Original problem was with leaking exhaust system and I also was not happy with the "rich petrol smell" from the exhaust, which I put down to a possible worn / incorrect seal on the metering unit, I had lived with this problem for the last year but finally thought that I should sort this out (wife keep complaining about the "exhuast smell" on our clothes after being in the car).

 

Therefore as I had a "spare" metering unit, PRV & 6No injectors that had both been rebuilt last year by K Raven-Smith (125bhp setup)- I thought that it was time to fit these to the car.

I also ordered a new twin sports exhaust system (double S manufacture - really nice units), underslung throttle linkage unit (from Prestige) and over the last 2 weeks / weekends I finally fitted it all.

 

Also fitted new GKN spsrk plugs (already have a lumentrion electronic unit fitted to the distributor, new cap and RED rotor, silcone leads, 12V sports coil - all fitted last year), Oil and filter change for good measure -- then the problems seem to have started.

 

When I start the engine it seems to run ok (slightly higher tickover at 1000rpm) and revs quite smoothly, but when I take it out for a road test / run, it seems to lack power - very hesitant / rough running below 3500rpm, it only seems to "GO" when I get past 3500rpm.

 

I have carried out a compression test and get the following psi readings :- No1 200, No2 195, No3 200, No4 195, No5 200 & No6 205 - which all seem to be fine and within the 10% rule.

I have checked the timing with a strobe and when I can get it to tick over at 850-ish rpm I noted as being between the 4-8 degree ATDC mark on the fan pulley.

 

Sorry for the long topic notes - but thought it best to describe want I have changed and checked to-date.

 

Any help / suggestions would be welcome - before I open the fuel pipe and "light her up".

 

Pat

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.... when I can get it to tick over at 850-ish rpm I noted as being between the 4-8 degree ATDC mark on the fan pulley.

 

 

 

4-8 ATDC on the pulley? It's late and have had a few beers but I thought it should be around 8-11 BTDC @850rpm

 

 

 

 

 

Edited by jobster
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Hi Jobster.

 

Thanks for the reply, I will check this again tomorrow, Sure its showing 4-8 ATDC - the strobe light is showing the mark to be on the right hand scale of the fan pulley as you look from the front.

 

Pat

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.....underslung throttle linkage unit (from Prestige) ......the 4-8 degree ATDC mark on the fan pulley.

 

Ditto what Jobster said.

 

Also, if you have not rebalanced the butterflies with your new linkage, that will muck things up below 2,000rpm.

 

Ivor

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Hi 88V8.

 

I do not have any problems with low rpm running + very good responsive reving at standstill (no engine loading), I have set up the throttles / butterflies with a vacuum gauge (all within 2 to 3 on the unit), but will still check the timing marks as per Jobster's comment (but must admit to trying both ways (retard / advance) on the distributor - with no improvement on road testing load.

 

Pat

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Spark Timing: 4ATDC sounds to me like a USA setting with the vacuum retard working at tick-over. Static setting on PI engines is about 10-12 BTDC and I dont see any way that is going to go to ATDC- there is nothing that can do that in the disy. At 3500rpm when the engine comes on song all the c/f advance has come in and the retarded timimg will have less effect. So set up the timing to about 10BTDC, or a bit more if you have a lower compression head eg 15 BTDC (I use 18BTDC on 8.5:1 head). Actually you can find the optimum by slowly turning the disy with engine at tickover and set it to when the rpm are fastest, but keeping the rpm below 1000 when centrifugal would kick in.

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Quentin.

 

I belive its ok, looking through No6 port - oval shape to the top (!/4 - 1/2 moon shape) metal body of shuttle to bottom of opening ! as per haynes manual diagram A.

 

If it was 180degrees out would it be responsive and fully smooth on reving at stationary - wsould it not "miss fire" through rev range !.

 

One thing I am unsure about is the position of the rotor / distributor when set at No1 TDC, the rotor seems to be between 5 and 6 (o'clock) and not as the diagram in the book which is just past the 6 o'clock postion - don't realy know if this would make the problems I am experiencing - and to get to the position in the book this would mean taking off the distributor pedalstel and moving the drive shaft gearing (also oil pump drive dog) to obtain this new position, would this effect the cam shaft timing ?.

 

Pat

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Peter

 

Thanks for your reply, I will recheck and adjust these setting tommorow and try out the result of them (fingers crossed).

 

must admit to being puzzed with the timing marks on the fan pulley - as no matter which setting it is set upon it never seems to be fully responsive under load (revs ans sound great with no engine load).

 

Will report back tomorrow evening when I have checked / re-tried the advise / suggestions placed tonight.

 

Thanks for the all forum members assistance so far (got to get the beast back to full running - ready for the IWE at Harrogate).

 

Pat

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Maybe the crank damper has slipped and the timing marks are incorrect? This has happened to two of my 2500PI engines - worth maybe checking where TDC really is - make an old sparkplug into a positive piston stop (drillout the electrode and anchor a rounded off bolt into it) and turn the engine by hand/spanner to get a set point BTDC and ATDC and then measure between them on the pulley - certainly I'd set the timing by the best idle rather than the marks on the pulley unless you are 100% confident in them.

Edited by Mk1PI
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...I have checked the timing with a strobe and when I can get it to tick over at 850-ish rpm I noted as being between the 4-8 degree ATDC mark on the fan pulley...

 

Pat

 

 

Sounds like your strobe does not have an adjustment to show the degrees advance when synchronised on the TDC mark? In which case it would show ATDC,i.e. DYNAMIC, with the STATIC timing set BTDC. See the manuals for equivalents.

 

 

Stan

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Hi Jobster.

 

Thanks for the reply, I will check this again tomorrow, Sure its showing 4-8 ATDC - the strobe light is showing the mark to be on the right hand scale of the fan pulley as you look from the front.

 

Pat

 

 

The crank turns clockwise as you look from the front. So the pulley scale to the right of the TDC mark is BTDC, looking from the front.

 

You may find this useful http://myweb.tiscali.co.uk/tlweb/tr6/injection/pi_cards/card_1.htm

 

Andy

Edited by 67_gt6
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The crank turns clockwise as you look from the front. So the pulley scale to the right of the TDC mark is BTDC, looking from the front.

 

You may find this useful http://myweb.tiscali.co.uk/tlweb/tr6/injection/pi_cards/card_1.htm

 

Andy

 

 

I missed that, then the advance must be pretty large and at no load won't matter. However, with the maximum advance of the dizzy of 14deg. coming in at around 2600RPM the timing may stay well below TDC after that under load.

 

Stan

Edited by smizgals
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Pat,

In this sort of case, it's always the last thing you did to the car, so forget cam or ignition timing - it's the injection unit!

 

I had just this - revs fine when not in gear, bogs down on the road.

It was the choke lever, pulled slightly on by a kinked cable, to shift the fuelling ramp upwrads, to go vastly rich on acceleration.

Push it back - instant response!

 

I always have an extra return spring on the lever nowadays.

John

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Hi Gents,

 

sorry I did'nt get back last night to update my results - I was still working on the car till 10PM and then was out of daylight (quite dark really).

 

Anyway update on results so far

Stan - you were spot on about the strobe adjustment button, I had simply "forgotten" that this was an adjustable unit and the button was fully set to an adavance of 40 degrees (as simple as riding a bike - but you must first remember where the peddles are !), once I had set this to 10 degrees it did line up / indicate approx 12 degrees BTDC at approx 850 - 900rpm, but to get it to tick over at this was only possible by pulling downwards quite hard on the throttle linkage ?.

 

John - your suggestion about an injection problem led me to double check that the choke and enrichment levers were fully returning to the off position - which they were.

I also checked that all the injectors were working and ejecting petrol - all new injectors were found to be ok and spraying a fine cone shaped mist pattern into a glass jar, but it was still running high at tickover - even with the air screw valve fully shut off (1100- - 1200 rpm).

I decided to check the intake bodies for any noticable leaks as I had taken these off to fit the exhaust manifold and gasket when installing the twin sports exhaust system, I did not find any air leaks around these intake bodies all seemed well.

 

During yesterday - my air flow meter arrived that I had ordered friday evening, so I decided to check the balance of each intake tube - what I found was that No1-2 & 3-4 would generally balance down to "3" on the meter, but 5-6 would not get below "8=10".

Thinking it might be a sticking spindle / butterfly I sprayed some silicon lubricant onto these areas, after working this spindle / butterfly for 10 mins I retested the air flow again, still same reading on Nos 1 to 4, 5 came down to approx "5" but 6 was still at "8" - seemed to me to indicate a slightly bent spindle / butterfly unit.

 

 

Desperation was now setting in and I was about to try and "adjust" the spindle with a gently "levering" action - it was only when I got out my large LED torch to see where the bent part of the spindle appeared, that I noticed that one of the butterfly retaining screws was missing (thankfully because it was now quite dark that I had to use the torch to check this area) and the butterfly was out of centre line - this in turn was catching the inner body and has resulted in a slight groove to the inner body.

 

Luckily I have "old" set of CP intacke bodies - which although not in perfect condition would at least enable me to salvage 1 unit to replace this damaged unit - I have now managed to fit this spare body and have run the car air flow readings now Nos 1 to 4 still "3", 5&6 now "4", - it is much better on tickover (850 900 rpm now) still about 12 degrees BTDC on strobe unit -BUT still rough running on load, 70% better than before.

 

 

So now my question is - with these air flow values, will this cause the rough running when under load - slight hesitation when the accelorator is pushed hard down - then it takes off but seems to be slightly "miss firing", what sort of values should I expect to see with the strobe at different rpm ranges - say 1000, 1500, 2000, 2500, 3000 - any information would be of great assistance.

 

 

Pat

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Simon.

 

Thanks for the info on that previous thread, Just started reading it and it is very similar to my problem, hopefully it will help me get to resolving my problem before the IWE at Harrogate (don't really want to go in the Volvo).

 

Pat

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Pat,

 

I have similar values on my cone flow meter and no roughness.

 

The following are the mean degrees advance on crank in the manual:

 

RPM deg. advance

 

500 0

900 2

1600 7

2600 14

5500 14

 

The recommendation nowadays is to set the static to 10 deg. on the crank.

 

Stan

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I have to smile! I hope your problem is the same as mine coz it's easy! I didnt mention it before because my hesitation was only from idle. However, of course I can see that it could be. Had I known how easy and not scary it was to simply adjust the MU mixture I would have had a go ealier. My MU was newly reconditioned too (Neil of K_Raven_Smith). However, Neil (Revington) is quite clear that unless your engine is newly reconditioned too to original specs, its going to need a rolling road and bespoke MU set up anyway. That is surely true, however, my driveability has now gone from an intensely frustrating hesitation on take up to perfectly driveable again. Sure it could be better and I am hoping my new TBs will improve that further. Then one day, feeling flush a trip down to Revingtons will happen!

 

Anyway. Loose A1 locknut (I used a screwdriver and gentle hammer), then screw in (clockwise to richen) by hand 1/4 turn or maybe 1/2 turn. I started with a 1/4, tried a 1/2 turn and am now back to 1/4. However, I expect I need a 1/3. Peter Cobbold is probably right that I might only need to adjust A3. Might have a go at that sometime. Whatever you do, clearly mark the current position of all three mixture screws! so you can back. btw, if I sound like I know what I am talking about - don't believe it for a second! In fact read my 6 page saga and it will become only too clear! That said, there's nothing like problems and mistakes for the learning process :lol:

 

Good luck. I hope that's it

Cheers

Q

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Stan,

Thanks for the info on the RPM / Degrees - I will try this out Friday evening / Saturday and see how it measures up, But first I am going to try and illiminate the "slack" in the throttle cable and linkages.

 

Quentin,

I have printed out your original post (thanks to Simon who put a link to it on my post) and will be trying out the adjustment as you have suggested, this was also confirmed by Neil (K_Raven_Smith) who has sent me a PM after noticing my post during Tuesday evening - when he phoned me today to guide me through what to adjust on the refurbished metering unit, I do "HOPE" it works out as simply as your problem did.

 

I must admit that I did not think the metering unit could be adjusted by us owners without "special" equipment, but Neil has been very helpful in assisting me in how to "gently" adjust the metering unit - which I will try out this weekend (fingers crossed).

 

I would never had thought that by being a careful and considerate owner to my TR - by splashing out on the lovely upgrades / refurbished items to keep her healthy - that she would play me up by having a major tantrum and not let me drive her.

This I suppose is the joys of TR ownership.

 

Will keep you all posted on the results when I have carried them out.

 

Brilliant forum and superb members (hope to meet up with some of the forum members at the IWE forum meet).

 

Pat

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Update as promised.

 

Well I have finally managed to get the car running well, with a much lower CO2 level to boot.

 

During the weekend (in between numerous rain showers) I finally managed to get the car ticking over better, I had checked and tried re-adjusting the butterfly postions / air readings so many times that I'm sure they went into "auto" mode on their own when I got my spanners out.

During a fustrated throttle re-adjustment trying to balance the air flow, I tried out a suggestion as stated by Neil (K_Raven_Smith) to "loosen off" the butterfly screws which hold the disk to the spindle - and then lubricate all the parts (I used the 3-in-one high preformance silicon spray) and then gentle keep opening and closing the butterflies by hand (on the spindle linkage) for approx 5-10mins per intake unit - which should help aline the disks to the chamber as as best as posible, then carefully re-tighten the screws with the butterflies closed.

 

This I carried out over all 3No intake bodies, and when I rechecked the air flow readings, I managed to obtain a closer match to all intake bodies 1 to 4 now at "2" and 5-6 at "3".

 

I then retested the car under load - BUT still it was not smooth at low loads, back to rechecking and now possibly trying out the "tampering" with the metering unit - as per Quentin's suggestion / actions in his previous post.

 

I did mu final check on the butterflies / throttle linkage - and then suddenly noticed by accident (due to dropping a locknut off one of the linkage rods) that the butterflies were only opening approx 60 degrees at max throttle with the accelorator wedged to the floor, when I tried to adjust the linkages past this 60 degree postion - I ran out of thread / rod adjustment and the rods "popped" out of the knuckle ends - these rods were obviously not long enough to allow full throttle opening of 90 degrees.

 

As I could not source any left / right hand threaded rods of longer lenght on a sunday afternoon, I decided "plan B" was needed, this entailed putting back on the original throttle linkage unit - but needed better rod / links to the intake units from the main horizontial linkage bar.

 

I managed to obtain a 1Mtr lenght of 5mm threaded rod and hex nuts from my local B&Q store, which I cut to approx 110mm lengths (3No) and drilled out the original "barrel nuts / adjusters that was on the main linkage with a 5mm clearance drill -(the barrel nuts to the intake linkage already had a 5mm clearance hole) I then fitted these new rods with nuts either side of these barrel units and proceeded to set up the throttles again for one more time - finally success in obtaining full throttle opening of 90 degrees.

 

Road test time again - Horrible running - really rough under full load throttle - really p***ed oof now (where's those matches when you want them - trust me to only have an old box of "safety matches" to hand with a soft outer strip.

 

Decided to go through all items again for final time (spark, coil, cap, rotor, plugs, leads, fuel, injectors (bloody injectors) - could not beleive it, No2 was not working - petrol was in pipe line up to injector - but was not spraying (tapped it / pulled it - no good would not work) - also No 4 was "dribbling" I could not get this to improve - changed both injectors for "old units" and tested them in a jar - all ok nice cone spray, refitted these and the car magically transformed into much improved running - very slight hesitancy on pick up - BUT O so much better.

 

Right only thing left now was the rich running ( may as well try it can't possibly get any worse that it previousl was) to try and that's to adjust the metering unit _ as per Quentin's post and information from Neil by previous telephone call, slackened of A3 lockring - turned 1/4 turn anti-clockwise , recheck CO2 reading (no difference still "7.5 - 8" , turned another 1/4 turn and then retested CO2 value - Well I could hardly believe my eyes, the value had dropped right down to 3.5 - 4, when I went for a road test the car preformed great - even sounded better, seemed so much more responsive.

 

Hopefully this will assist with reducing the "rich petrol" smell and might even improve the MPG figures, I will need to log milage petrol usage over the next few weeks and see if there is any improvement.

 

This has been one hellish problem to sort out - with me very nearly "giving up" on trying to fix it - and coming close to throwing in the towel.

 

sorry for the long post - but I thought it best to confirm my results - in case it is of any assistance to others at a future date - just as per Quentin's post helping me to check an area /item that I might have otherwise dismissed.

 

Pat

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Pat,

 

Quentin adjusted A1 to enrich. A3 I understand is for minimal fuel delivery and have been advised to adjust that to cure backfire on overrun by turning it clockwise to enrich the mixture when the butterflies are closed, i.e. maximum vacuum. I am told having too little fuel at that point will damage the valves through overheating.

 

If the linkage that did not open the butterflies completely is from Prestige have a look at this thread: http://www.tr-register.co.uk/forums/index.php?showtopic=14973&hl=throttle.

 

Stan

Edited by smizgals
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If I remember correctly, you can adjust the accelerator pedal to get more travel, There should be a bolt under it that can be screwed in/out. I had a similar problem with the butterflies not opening fully.

 

Mark.

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Great news Pat! Though Stan is right. I turned 1/4 clockwise to richen up. This did away with my hesitation - well nearly. I tweaked it a bit more to about 1/3 which is where it still sits. I still get a faint hesitation but it is more noticeable aurally than in the drive. In other words I can pull away smoothly now where before I had to blip and gun the throttle. I am hoping any residual hesitation will go away when I fit my new throttle bodies which are due Friday! I have no idea about the CO levels and would really like to find out. I need to borrow someone's meter some time coz right now I'm all out of "squirreled away" cash! It's the Brunel meeting tonight and I would have asked there but sadly can't make it :(

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Mark V - I did not even known the accelorator pedel could be adjusted, will have a look at that.

 

Stan, Quentin - your both right about adjustment of A1 screw to "enrichen" - but mine was already way too rich, (air leaking past butterflies - only 7-8Hg 0n air flow meter)and as advised by Neil (K_Raven_Smith) whom rebuilt my metering unit, that the metering would be starting to call for fuel at this value.

Therefore he advised me to adjust A3 screw and recheck CO2 levels - also readjust butterflies if possible to get a better (higher) vacuum.

 

The adjustments have worked for me so far - and over the next few weeks I will be monitoring fuel consumption / CO2 values and listing for any adverse effects to the running of the engine (all with tightly crossed fingers) and hoping that all remains well.

 

Thanks again guys for your brilliant assistance with sorting / directing me to resolving my problem, just glad that if this is the sort of problems encountered with Lucas's mechanical fuel injection - THANK GOD they never got around to designing and fitting "ELECTRONIC" injection - we would really be screwed.

 

Pat

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