Any pointers on this TR4 engine (video)

[arallsopp]

Howdo. 
 

my neighbour has recently bought this TR3A with a 4 engine, and it’s not happy.

He’s fixed a fuel leak on the carbs and refurbed them with the burlen kit. Both gulp a lot of air (the only way to balance them is to bury the needle on our airflow meter).

The jets (H6) are wound out 9 flats for a start position, and the coil seems to have plenty of spark.

The engine runs hot. He’s turned the dizzy for the highest idle RPM and was still climbing when the vacuum advance blocked further twist by hitting the engine.

Here’s a slow mo video of the exhaust. It seems to be misfiring irregularly, or beating out some Latin American rhythm.  

Thought I’d share incase anyone has any pointers on what we might look at next. 
 

it just seems to gulp so much air, or grumble to a halt. 
 

cheers!

Andy. 

[arallsopp]

Oh, lest relevant, what’s been identified as the (previously plugged) vacuum advance coming off the carb end seems to have oil weeping out of it. It’s a little metal pipe that pivots. 
 

The dashpots feel very heavy to me, but I’m comparing them with a well fettled spit so that might be normal. 

[Colin Lindsay]

It's a lovely rhythm, I was already writing a tune to go with it...

Last time I heard an engine like that, it was heavily coked up and was continuing to ignite and was running on even after the engine was turned off. Has it been running very rich?

[Pete Lewis]

i suggest over advanced and in need of a compression test to start with

check the dizzy has no wear side float on the points cam shaft 

does it have a spurious electronic unit fitted ???

tappet gaps  been checked ???

Pete

[arallsopp]

Thanks @Colin Lindsay. The mixture was definitely off, and very sooty plugs suggest it was run too rich by the PO. That (plus the leaking carb) was our trigger for the carb strip and rebuild 

it’s a bit of a moving feast really. When trying to establish timing, we found we couldn’t roll it in neutral. Turns out the rear calliper was seized and locked on, so the 16 delivery mile drive home must have been a fair amount of revs and load. I don’t think it’s had the love it necessarily deserves.

Compression test is a good call, @Pete Lewis. The dizzy shaft feels reasonably free from play, but there’s deep scoring to the contact plate so something is/was amiss. Looks like a new cap has been added recently.

There’s a “newtronic ignition system” of dubious heritage installed, which we will look to bypass and roll back to points. Tappets entirely unexplored as yet. I’m just getting started on my classic car journey. Would they do this?

Engine running cooler than it was, even considering the coolant it’s shared with the garage floor. Oil leaks and burning smells seem to have been reduced by changing rocker gasket and deep cleaning the engine bay.

Andy  

 

 

 

[Pete Lewis]

you only need a couple of tight/ zero gapped tappets to really upset things 

Pete

 

[arallsopp]

Got you. Thanks @Pete Lewis
 

Is it still a case of aiming for .012 with a feeler guage and:

- Turning engine to #1 piston TDC by aligning timing mark and pointer with the distributor rotor pointing to the #1 plug contact.

- Set intake and exhaust for #1, intake for #2,  exhaust for #3.

- Turn engine one complete revolution (aligning timing mark and pointer).

- Setting exhaust for #2, intake for #3, intake and exhaust for #4.

[trigolf]

2 hours ago, arallsopp said:

There’s a “newtronic ignition system” of dubious heritage installed, which we will look to bypass and roll back to points.

I've had a Newtronic ' Pihrana' optical igntion system fitted to my Vit for 15+ yrs now and it's always been 100% reliable. So I wouldn't condemn it yet until further checks have been carried out on the ignition system.

[Iain T]

14 hours ago, arallsopp said:

The dashpots feel very heavy to me, but I’m comparing them with a well fettled spit so that might be normal. 

Heavy with the damper out? If in it could just be normal damper oil resistance. Or someone might have used installed very strong damper springs. 

Have you any air leaks in the intake system? 

Good exhaust rhythm 😂

Iain 

Edited November 27, 2023 by Iain T

[arallsopp]

4 minutes ago, Iain T said:

Heavy with the damper out? 

Have you any air leaks in the intake system? 

Howdo Iain. 
 

Heavy on the lift pin. Oil in, but there’s more resistance than I’d expect from just the fluid. It’s correct spec and the piston dropped normally when dismantled. Maybe the needle is fouling it. 
 

Tested for air leaks with a spray of WD40 around the gaskets and sundry. No change in engine note or pattern I could discern.

thanks. 
 

andy. 

[Iain T]

15 minutes ago, arallsopp said:

dropped normally when dismantled. Maybe the needle is fouling it. 

Hi Andy. Dropped easily with a metal clonk with the damper out? If so the needle centring should be OK. Both needles screwed in the same and evenly balanced? If so is it my favourite subject fuel starvation? Does it have a fuel filter and is it blocked? If the float chambers are 'just' filling when that fuel is used the engine will cough and splutter although mine didn't have the same rhythm! 

Iain 

Edited November 27, 2023 by Iain T

[dougbgt6]

Andy,

To adjust the tappets use the rule of 9. With the hand brake off, the engine in high gear AND battery disconnected, rock the car back and forth.

Turn the engine till No.1 is fully down and adjust No.8 (1+8 =9)

Similarly No.2 fully down adjust No.7 (2+7 =9)

No.3 down adjust No. 6 (3+6 =9)

And so on. 

Doug

 

 

[arallsopp]

Thanks @Iain T. 
 

not quite a clean clonk, more like putting a pint down on a slightly dog eared beer mat. But it does sit. 

Jets balanced.

 

There’s an inline filter near the carbs that looks clean. Electric pump so presumably one down there somewhere too. Tank has been allowed to run empty so that’s a good call to check it. Runs happier at higher revs so don’t think it’s starvation, but can isolate that at least.

Andy  

 

[arallsopp]

Cheers @dougbgt6.  Wasn’t sure if there was a shortcut on this. 

[Iain T]

9 minutes ago, dougbgt6 said:

To adjust the tappets use the rule of 9. With the hand brake off, the engine in high gear AND battery disconnected, rock the car back and forth.

Or cheese grater your knuckles and turn the engine over with a spanner. Although on a 4 pot there must be more space. 

[Iain T]

Can you install the air piston 180 degrees out on an HS6? It's a long time since I fiddled with an SU. 

Iain 

[Pete Lewis]

we havnt discussed fueling with the dreaded rubber slivers blocking a float needle valve created by fitting nastybrubber hose over metal pipes

and on SU its worth also look under the jet tube spiral wrap to see if the plastic tube has a hidden kink.

and yes  Dougs rule of 9 works well 

the vac tube to the dizzy has no effect on running it advances at cruising throttles as its just an economy device .

but if the spring in the vac diaphragm has failed  ti will not return the base plate to any fixed position 

check with short pipe and suck  and watch !!!

 

[Pete Lewis]

air piston is located witha tag on the case and groove in the piston so  ...No  

but you could get into trouble with a biased needle set up 

went to a spitty in trouble and the needle sat in the jet when the piston raised  ,  just been left loose 

but not easy to see (well with varifocals and false teeth  ha !)

[dougbgt6]

Andy,

It's not Doug's rule of 9, it's Pete's, he taught me.

I claim the rule of 13 for 6 cylinder engines!

Doug

[Pete Lewis]

heck i get the blame for everything    Ha !!

then if you get each cyl on its compression stroke TDC you can set both inlet and exhaust on each cylinder 

one at a time  saves turning the engine so much .

it will run fine with a big gap but clatter , a tight gap will upset the running /lumpy idle 

a zero gap will cause a full misfire as the valve cant close fully 

Pete

[johny]

On 26/11/2023 at 20:33, arallsopp said:

my neighbour has recently bought this TR3A with a 4 engine, and it’s not happy.

He’s fixed a fuel leak on the carbs and refurbed them with the burlen kit. Both gulp a lot of air (the only way to balance them is to bury the needle on our airflow meter).

The jets (H6) are wound out 9 flats for a start position, and the coil seems to have plenty of spark.

The engine runs hot. He’s turned the dizzy for the highest idle RPM and was still climbing when the vacuum advance blocked further twist by hitting the engine.

Here’s a slow mo video of the exhaust. It seems to be misfiring irregularly, or beating out some Latin American rhythm.  

Thought I’d share incase anyone has any pointers on what we might look at next. 

it just seems to gulp so much air, or grumble to a halt.

Think as with any new car to you best to do a complete check over and set up from scratch. The workshop manuals for both TR3 and 4 are available here vitessesteve.co.uk for free download and have all the required info with pictures👍

[arallsopp]

27 minutes ago, johny said:

Think as with any new car to you best to do a complete check over and set up from scratch. The workshop manuals for both TR3 and 4 are available here vitessesteve.co.uk for free download and have all the required info with pictures👍

Agreed. We are picking through. Hadn’t thought to check vitesse Steve. That’s a brilliant resource.