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Hi all

Help please if you can

I have just started to run my 3a engine and i cannot stop it pinking under load

The spec is as follows

New piston liners to 2.2 ltr

Sports exhaust/Hs6 carbs on tr4 manifold with sm needles...tried tw and just the same

Standard cam and standard tr3a head

Distributor standard with 14* weights and its turned advanced as far as possible that's its now up against the block!

Compressions all around 170psi

It starts on the button and ticks over nice and steady and when you blip the throttle is responsive

Im running it on normal fuel but have added an octane booster but no difference

Any ideas would be great!

Thanks

Tony

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Hi Tony,

you do not say what your static ignition timing is.

Set it to 4' BTDC. If you can;t set it then retard it a little and then find a hill. Go u at abput 40mph i 4th and then put your foot down.

If it pinks then retard some more. If it doesn't then advance a little and repeat.

 

Are you burning oil - this will reduce the octane value.

 

Roger

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Hi

Started at 4 but have advanced it to now around 12 degrees and its just the same

Not burning any oil

Very strange...im at a loss at present and don't want to damage the new engine

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Do you think the compression is too high?

How would we know ?

 

what is it calculated to be ? what did you skim off it, what thickness is left on the head ? what cylinder head gasket is fitted copper composite/solid copper/pressed steel/steel and composite ? What gasket size has been used in bore mm 86/87/89 etc etc

Unless you come up with something telling within this information needed I'm guessing you've got a hotspot in one or more cylinders. Possibly a sharp edge left on the edge of a cylinder or the combustion area.

 

Mick Richards

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Can I get this right? You have advanced the ignition to try to cure pinking?

Desperation I think.

 

Mick Richards

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I haven't skimmed the head but then i dont know its previous history

A hot spot sounds possible as ive checked the ignition and carbs a dozen times

Ill take the head off and take a look

Thanks

Tiny

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I haven't skimmed the head but then i dont know its previous history

A hot spot sounds possible as ive checked the ignition and carbs a dozen times

Ill take the head off and take a look

Thanks

Tony

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It is unlikely although possible it is a hot spot.

 

It is far more likely the ignition is too far advanced for the fuel octane rating being used.

 

I had a pinking problem at higher revs under load. Even with the ignition retarded a fair way it would still pink. Talking to some mates they asked what fuel I was using to which I answered Shell 98. They said it is the worse 98 in Australia.

 

I switched to BP Ultimate 98 and the problem was solved and even allowed a bit more advance and power. Just because the manufacturer says it is 98, or whatever octane, doesn't mean it is.

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Are you using the timing pointer and crank pulley drilled hole as you reference for degree timing?

Have you checked the piston on Nos 1 & 4 are actually at top dead centre when the pointer on the timing cover aligns with the hole drilled in the crank pulley rear half?

 

It is possible to re assemble the crank pulley with the timing mark hole many degrees out. I have seen it done - on a 'miracle' TR2 that had had everything done to cure the pinking issues.....

 

Peter W

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+1 on checking the crank pulley assembly to ensure the timing hole is correctly in position, good call from Peter W.

 

Mick Richards

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Hi Tony,

before attacking the head (a hot spot will give 'run on' rather than pinking) do follow what has been supplied on here. Check the timing and even if it is right progressively retard the spark until the pinking has gone.

 

Being a 3A I assume you do not have a PCV on the engine breathing - if you do, remove it and replace with a length of rubber rubber to vent over the side.

Check the plugs for oiling - oil reduces the octane value and will cause pinking.

 

Roger

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Thanks for all the advice

I've tried every way with the dizzy and its still doing it

So.....I've started to take the head off for a look!

At least ill be able to get the tdc on the narrow belt pulley spot on....why don't they mark them up at the factory?

Ill keep you all posted!

Thanks again

Tony

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Just an add on

Is there a way to lift the head without disturbing the liners?

Also whilst its off does anyone know what the head chamber volume should be so i can establish if its been skimmed before

Thanks

Tony

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Hi Tony,

if you have an engine hoist this would make light work of the head. otherwise use wooden wedges to get it moving.

 

DO NOT turn the engine over when removing the head pr afterwards.

 

When establishing TDC make sure the liners are clamped down firmly.

 

Roger

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Just an add on

Is there a way to lift the head without disturbing the liners?

Also whilst its off does anyone know what the head chamber volume should be so i can establish if its been skimmed before

Thanks

Tony

So, new narrow belt kit and no timing mark? Did you add any TDC mark, when fitting the bottom pulley?

If not and the TDC was guessed the distributor could be way out of timing.

 

Two steps I think

1: - Establish TDC on the pulley and mark it. Pig of a job with the apron fitted - take the RH horn off as a minimum for more arm room. refit the cylinder head to retain the liners while turning the engine over with the plugs removed. See where your distributor timing spark relates to REAL TDC. If horribly out, then it may be the solution to your pinking issues. You may also have to remove and refit the distributor drive in the right place to get the distributor correctly orientated.

 

2: - You need to do some measuring of your engine now.

 

If you are aiming at 9.75 : 1 (not an unreasonable CR in a TR - original TR4 was 9.0 : 1)

 

Then with 87 mm bore flat topped pistons, and 87 mm bore gasket hole, a gasket of 0.75mm (0.030") thick (shim steel are 0.020" and solid copper 0.040"), a 92 mm stroke, a deck height of 0.5mm (0.020") (could be plus or minus your hat)

 

Obviously if you are using a different thickness gasket or different deck height (piston top to liner top clearance at TDC), these figures will need restating in the calculator.

According to this calculator.

http://www.csgnetwork.com/compcalc.html

 

For 9.75 : 1 the chamber volume/capacity should be roughly 55 cc

For 9.5 : 1 the chamber volume/capacity should be roughly 57 cc

For 9.25 : 1 the chamber volume/capacity should be roughly 59 cc

For 9.0 : 1 the chamber volume/capacity should be roughly 61 cc

 

Use of the calculator is easy to find CR or chamber volume. Type in the dimensions you know, except chamber volume, add CR at bottom, then press calculate chamber volume to find out what you are looking for.

Or if you know the chamber volume, type that in with all the other dimensions and press calculate CR. and be horrified!

 

 

Read this too http://chainganger.co.uk/Page2/PDF/CalcCR.pdf

 

Peter W

 

PS If I remember correctly - an old TR rule of thumb for TR2/3 owners was - change your 83 mm pistons to 86 mm and do nothing else and the CR will rise from 8.5:1 to 9.0:1 -assuming you do nothing but refit the original TR2/3 cylinder head. So instant CR rise and more cc's. This sounds like what you have done. But why it is pinking ? - Is you timing correct? what fuel and how fresh?

Edited by BlueTR3A-5EKT
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You need to do some measuring of your engine now.

 

If you are aiming at 9.75 : 1 (not an unreasonable CR in a TR - original TR4 was 9:1)

 

Then with 87 mm bore flat topped pistons, and 87 mm bore gasket hole, a gasket of 0.75mm (0.030") thick, a 92 mm stroke, a deck height of 0.5mm (0.020")

 

Obviously if you are using a different thickness gasket or different deck height (piston top to liner top clearance at TDC), these figures will need restating in the calculator.

According to this calculator.

http://www.csgnetwork.com/compcalc.html

 

For 9.75 : 1 the chamber volume/capacity should be roughly 55 cc

For 9.5 : 1 the chamber volume/capacity should be roughly 57 cc

For 9.25 : 1 the chamber volume/capacity should be roughly 59 cc

For 9.0 : 1 the chamber volume/capacity should be roughly 61 cc

 

 

Read this too http://chainganger.co.uk/Page2/PDF/CalcCR.pdf

 

Peter W

 

PS If I remember correctly - an old TR rule of thumb for TR2/3 owners was - change your 83 mm pistons to 86 mm and do nothing else and the CR will rise from 8.5:1 to 9.0:1 -assuming you do nothing but refit the original TR2/3 cylinder head. So instant CR rise and more cc's. This sounds like what you have done. But why it is pinking ? - Is you timing correct? what fuel and how fresh?[/quot

e]

Ive got 87 mm piston liners and a standard 3a head but as i bought a non runner i don't know if the head has been skimmed

Thanks for the info i should be able to determine the cr from it

I did fill it with supermarket fuel so its fresh but maybe not that good but i have added an octane booster

The head is now off and there is a bit of damage around no 4 cylinder from a previous life valve drop..don't know how i missed it on the rebuild! So ill smooth it out

Also the tdc position was 5* out so there's a few things to sort out

Thanks

Tony

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You need to do some measuring of your engine now.

 

If you are aiming at 9.75 : 1 (not an unreasonable CR in a TR - original TR4 was 9:1)

 

Then with 87 mm bore flat topped pistons, and 87 mm bore gasket hole, a gasket of 0.75mm (0.030") thick, a 92 mm stroke, a deck height of 0.5mm (0.020")

 

Obviously if you are using a different thickness gasket or different deck height (piston top to liner top clearance at TDC), these figures will need restating in the calculator.

According to this calculator.

http://www.csgnetwork.com/compcalc.html

 

For 9.75 : 1 the chamber volume/capacity should be roughly 55 cc

For 9.5 : 1 the chamber volume/capacity should be roughly 57 cc

For 9.25 : 1 the chamber volume/capacity should be roughly 59 cc

For 9.0 : 1 the chamber volume/capacity should be roughly 61 cc

 

 

Read this too http://chainganger.co.uk/Page2/PDF/CalcCR.pdf

 

Peter W

 

PS If I remember correctly - an old TR rule of thumb for TR2/3 owners was - change your 83 mm pistons to 86 mm and do nothing else and the CR will rise from 8.5:1 to 9.0:1 -assuming you do nothing but refit the original TR2/3 cylinder head. So instant CR rise and more cc's. This sounds like what you have done. But why it is pinking ? - Is you timing correct? what fuel and how fresh?[/quot

e]

Ive got 87 mm piston liners and a standard 3a head but as i bought a non runner i don't know if the head has been skimmed

Thanks for the info i should be able to determine the cr from it

I did fill it with supermarket fuel so its fresh but maybe not that good but i have added an octane booster

The head is now off and there is a bit of damage around no 4 cylinder from a previous life valve drop..don't know how i missed it on the rebuild! So ill smooth it out

Also the tdc position was 5* out so there's a few things to sort out

Thanks

Tony

 

 

According to TeriAnn

TR high port heads are 3.33 " thick - how thick is yours?

 

Peter W

Link

 

http://tr3a.info/FAQ_heads.htm

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According to TeriAnn

TR high port heads are 3.33 " thick - how thick is yours?

 

Peter W

Link

 

http://tr3a.info/FAQ_heads.htm

 

 

Just been out to check and its 3.334 so looks as though its never been skimmed

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So what cylinder head gasket is fitted copper composite/solid copper/pressed steel/steel and composite ? What gasket size has been used in bore mm 86/87/89 (don't assume measure it). Does any of the gasket intrude into the compression chamber ? if it does immediately in front of the inlet valve it should still be ok, the incoming petrol charge preserves it, some where else around the circumference and there may be problems. Also what's the compressed thickness ?

 

Mick Richards

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Hi Mick

The old compressed gasket ive taken off is 1.4mm thick..its doesn't protrude into the compression are so looks ok

Its rimmers standard offering and looks to seal ok

Ive measured the chamber volume and its 58cc so from Peters info cr is around 9.5

Thanks

Tony

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