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TR6 Timing/Ignition issues


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Hi all,

 

So I have made a weekend trip back home and my dad asked me to take a look at his 6 as it wasn't starting properly. He had adjusted the timing just so the car would start so he could get it back in the garage before the winter hit and since then not much has happened.

 

It has recently had a rebuild but immediately after that it was idling high (around 1600rpm) and I think that is too high even with a fast road camshaft (is that correct?).

 

I took it for a drive today and took my trusty timing strobe gun and my backup light bulb with two bits of wire to try and sort the timing.

 

Immediately I noticed that it was now idling lower. This probably wasn't 'fixed', more likely a result of poor timing. Suspicions confirmed noticing it could not rev above 3000rpm.

 

I set the timing first using static timing to 4°ATDC. Took it for a drive and still not right. Then I tried using stroboscopic timing, but ran into a problem. The timing is to be set to 11° at 850rpm. I couldn't get the car to idle that low AND have 11° timing. So I got it as close as I could and then went for a bit of a drive. It seemed better here and then I decided to try fine tuning it to see if I could get it to be right.

 

By using the little advance/retard wheel on the side of the dizzy, I took it down in quarter turns. Doing this up and down the A38 pulling over at every SOS phone box, I noticed that I was really backing off the timing, and was almost at 28°. That to me seemed like far too far, so I put it back nearer 14 and limped it home.

 

 

Regardless of what I did, the car would not pull past 3500rpm. I would describe it as bogging but that might not be the right word.

 

To the point! Do you suspect that it is just a case of timing error, or is there perhaps a bigger demon at work that I need to address.

 

Thanks, Sam.

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Sam

I think you need to tell us what type of engine you have, either PI or carbs.

 

John

AH YES! I knew I had forgotten something.

 

Right, it's the Injection Model bit more:

 

Standard Injection

Chassis Code begins with CR17

Lucas Distributor 41501 B

Fast Road Cam (supposed to give 180bhp, hilarious!)

All else is pretty bone stock

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Hi Sam,

 

Has it ever run properly since the new cam was fitted?

 

I would double check the valve timing. Once that is confirmed to be correct set static timing to 10°. It may also be worth checking the Injection timing. However if it has run properly since the new cam has been fitted the valve and injection timing are probably OK.

 

Fuel delivery - does pump maintain pressure at higher revs?

 

Chris

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Hi Sam,

 

Has it ever run properly since the new cam was fitted?

 

I would double check the valve timing. Once that is confirmed to be correct set static timing to 10°. It may also be worth checking the Injection timing. However if it has run properly since the new cam has been fitted the valve and injection timing are probably OK.

 

Fuel delivery - does pump maintain pressure at higher revs?

 

Chris

 

Hi Chris,

 

Since the cam was fitted it has run properly with one exception, that it idled very fast. How would you suggest checking valve timing, is it a rocker off, and hand turn the crank and check what angle a valve opens at? If so I'm sure I can manage that.

 

As for the fuel pump, I have no idea how I would test the pressure at higher revs, is there an agreed upon way to do this?

 

Sam

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If it's idling fast then it suggests an air leak in the induction path. Check that the MU vacuum pipe is sound and that the diaphragm holds a vacuum using the tongue test. Have a good look around the inlet manifold/gaskets. Then back to basics by setting up the butterflies.

Edited by peejay4A
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If it's idling fast then it suggests an air leak in the induction path. Check that the MU vacuum pipe is sound and that the diaphragm holds a vacuum using the tongue test. Have a good look around the inlet manifold/gaskets. Then back to basics by setting up the butterflies.

I also suspect a leak in the induction path. Tomorrow I will start it up and put my hand over the intake plenum thingymajig to see if it will idle properly, I reckon the butterflies might be letting in some excess air so if I can cut off everything before the bleed screw that should confirm suspicions.

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If you screw the idle ( air bleed) screw in all the way and the car still idles, the you have an air leak!

 

Very common after a rebuild as it takes a while for the intake butterfly valves to reseal.

 

Whereabouts are you/is your dad?

 

There's mist likely a nearby Register member who'd be more than happy to help :-)

 

Steve

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If you screw the idle ( air bleed) screw in all the way and the car still idles, the you have an air leak!

 

Very common after a rebuild as it takes a while for the intake butterfly valves to reseal.

 

Whereabouts are you/is your dad?

 

There's mist likely a nearby Register member who'd be more than happy to help :-)

 

Steve

 

 

Just north of Birmingham in Sutton Coldfield, if anyone is willing to help it would be most appreciated! Plus would be nice to get to know some Triumph owners in the area as I often see a couple rolling round.

 

And yes I believe it is the throttle butterflies as they were ultrasonic cleaned so they have lost all the coke that sealed them before. I might plug up the plenum, and then use the idle bleed to set the rpm just for the tuning purposes as I believe the butterflies could be interfering.

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Hi Sam,

 

It doesn't sound as though the cam timing is the culprit but just for reference there is some info here

http://www.tr-register.co.uk/forums/index.php?/topic/7432-valve-timing/

 

Regards

 

Chris

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