TR4a Commissioning Thread

[Lebro]

I have a Revotech fan, & it works very well, but not with the supplied controller. After it failed twice  I now use an Otter switch.

Bob

[Steven Whitaker]

21 hours ago, Lebro said:

I have a Revotech fan, & it works very well, but not with the supplied controller. After it failed twice  I now use an Otter switch.

Bob

Thanks Bob.  Which switch did you use please?  What temps does it come on and off?  Did you buy the pipe too?

[Steven Whitaker]

On 8/17/2026 at 3:48 PM, james christie said:

Just to add a few bits of practical info. 
The Otter switch comes with options as to the temperature when it switches the fan on. Mine is 82°C.

Unless you have greater brazing skills than I, it might be worth buying the down pipe complete with the boss for the switch. https://www.moss-europe.eu/fr-fr/pipe-water-return-stainless-steel-130039sst
I too went to the Otter switch arrangement as the original Revotec proved to be faulty. Otherwise I find the Revotec kit excellent and reliable.

james

Hi again.  Is your switch on a TR4?  Tnx

[RogerH]

Hi Steven,

Bob has a TR3.  The pipe is common through ther TR2-4A range  (4 pot engines)

See here  Pipe   # 29 & 29A

See here for the switch   Switch    The 88 - 79'C is popular.

Roger

[james christie]

Roger has answered the question I think. I have a TR4A engine in my 3A but the two engines are virtually identical.

james

[Steven Whitaker]

Thanks Roger and James.  I’ll get a switch and pipe on order.

[Steven Whitaker]

4 hours ago, RogerH said:

Hi Steven,

Bob has a TR3.  The pipe is common through ther TR2-4A range  (4 pot engines)

See here  Pipe   # 29 & 29A

See here for the switch   Switch    The 88 - 79'C is popular.

Roger

Is that the Otter switch Roger?

[Lebro]

14 hours ago, Steven Whitaker said:

Thanks Bob.  Which switch did you use please?  What temps does it come on and off?  Did you buy the pipe too?

As said above Pipe common to TR4, mine was stainless steel from the TR shop, & Yes 88° switch is what I use, with a manual override 

Bob

[rcreweread]

13 hours ago, RogerH said:

Hi Steven,

Bob has a TR3.  The pipe is common through ther TR2-4A range  (4 pot engines)

See here  Pipe   # 29 & 29A

See here for the switch   Switch    The 88 - 79'C is popular.

Roger

I had some of these ( the pipes not the switch) on my stand at Malvern but no one bought one ! They were right next to the forum meet area

Cheers Rich

[Steven Whitaker]

So, I got her running (albeit roughly) after the full nut/bolt rebuild of the entire car/engine etc. and this morning at 6:30am I drove her to a garage to set the carbs and ignition up better.  I was incredibly nervous that she would end up on a trailer, but we got there (15 miles) under our own steam in a steady 45 mins.  Very pleased.  Thanks to everyone so far, for helping me on my first TR restoration.

 

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[Lebro]

Well done, lovely looking car

Bob

[TR NIALL]

Congratulations on the finished Car now the last few little tweaks and Happy Days.

[Steven Whitaker]

Thanks.  Plenty still to do.  So the current topic is tick over.  It’s rough.  Timing done, mixture set with a gas analyser and colour tune, carbs balanced and set up, but it’s still running lumpy.  It’s fine under power but not nice to drive in traffic.  Is there a way I can share a video of it ticking over on here, so you can offer your comments please?  It pulls ok but it’s really not nice to drive as is, especially on the over run when taking the foot off the gas.  Everything is clean.  Carbs have new chokes and jets etc. and I ultrasonically cleaned them when I rebuilt them.  Engine is on running in oil and I’ve done about 30 miles after full engine rebuild which involved everything new including unleaded head.  The exhaust is a tubular manifold and the exhaust is a Phoenix twin pipe system from TR shop.  I’m not keen on the exhaust sound.  It’s somewhat muffled and not clean/crisp and wonder if this is causing an issue.  Any ideas?

Thanks, Steven

[TR NIALL]

11 hours ago, Steven Whitaker said:

Thanks.  Plenty still to do.  So the current topic is tick over.  It’s rough.  Timing done, mixture set with a gas analyser and colour tune, carbs balanced and set up, but it’s still running lumpy.  It’s fine under power but not nice to drive in traffic.  Is there a way I can share a video of it ticking over on here, so you can offer your comments please?  It pulls ok but it’s really not nice to drive as is, especially on the over run when taking the foot off the gas.  Everything is clean.  Carbs have new chokes and jets etc. and I ultrasonically cleaned them when I rebuilt them.  Engine is on running in oil and I’ve done about 30 miles after full engine rebuild which involved everything new including unleaded head.  The exhaust is a tubular manifold and the exhaust is a Phoenix twin pipe system from TR shop.  I’m not keen on the exhaust sound.  It’s somewhat muffled and not clean/crisp and wonder if this is causing an issue.  Any ideas?

Thanks, Steven

Maybe a trip to a local Rolling Road Expert and get it all set up properly.

[qkingston]

Hi Steven, I watched this video made by Erin Yakov (Rusty Beauties), it might give you some clues as to where to look

David 

 

[Steven Whitaker]

Thanks David / Niall.

I've only done 30 miles in it, so too soon for a rolling road I reckon.

But there is something in the system that's making it lumpy.  Need to find the gremlin.  The cam is an unknown.  How can I check the cam without removing it.  It's been to a local Triumph man and he's got it as good as he can.  But neither of us are happy with it.

Could it be due to everything being new, tight, on running in oil, new exhaust.  Its had a new coil, points, plugs, condenser, new leads and dizzy cap.  Dizzy is the old original one, the only thing I've not replaced on the car.  I fully rebuilt the carbs with new jets and chokes etc.  We really cannot understand it.

Will running it in for more miles help?  I'm struggling to know what to do next.

[Lebro]

Could it be a "race" type camshaft.

They are designed to give their best at high revs, & often make for a lumpy idle.

Bob

[stuart]

1 hour ago, Steven Whitaker said:

.  Its had a new coil, points, plugs, condenser, new leads and dizzy cap.  Dizzy is the old original one, the only thing I've not replaced on the car.  

 

Where did you get those parts?  I would have the dizzy rebuilt by our pal Martin https://distributordoctor.com/ You would be surprised what a difference that makes.

Stuart.

Edited August 26 by stuart

[Steven Whitaker]

1 hour ago, Lebro said:

Could it be a "race" type camshaft.

They are designed to give their best at high revs, & often make for a lumpy idle.

Bob

Could be Bob.  I have no idea about the history.  How could I check this?

[Steven Whitaker]

1 hour ago, stuart said:

Where did you get those parts?  I would have the dizzy rebuilt by our pal Martin https://distributordoctor.com/ You would be surprised what a difference that makes.

Stuart.

I got all my bits from TR Shop.  DIzzy Doctor rotor arm and condensor from TR Shop too.  Thanks.

[Lebro]

54 minutes ago, Steven Whitaker said:

Could be Bob.  I have no idea about the history.  How could I check this?

Easiest way would be to ask whoever built the engine.
Any other way would require a lot of measurements of valve lift / timings etc.

Another thought, following on from this, is the valve timing correct. Again not that easy to check, but doable.

Bob

Edited August 26 by Lebro

[Steven Whitaker]

4 hours ago, Lebro said:

Easiest way would be to ask whoever built the engine.
Any other way would require a lot of measurements of valve lift / timings etc.

Another thought, following on from this, is the valve timing correct. Again not that easy to check, but doable.

Bob

I rebuilt it.  But don”t know the history of the car at all.  Measurements might be an option.  Thanks.

[Ralph Whitaker]

Would be fairly easy to check the lift on the cam with a dial gauge and compare with standard.

Ralph

[Steven Whitaker]

2 hours ago, Ralph Whitaker said:

Would be fairly easy to check the lift on the cam with a dial gauge and compare with standard.

Ralph

Hi Ralph.  Would this be a case of removing the rockers and having the DTI on top of a push rod?  Could be tricky as the push rod wouldn't be 'located' by anything so measuring would be inaccurate?  Are all lobes the same and where can I get standard figures from.  Certainly would be handy if I can diagnose without removing the cam.  But then that would only tell me the lift, so how about measuring the ramp up and down and the dwells etc?  Could take forever and be quite tricky do you think?

[Rob Salisbury]

I'm going to make some assumptions here but a very simple method to get you in the right ballpark is, assume you have a standard 4A cam (17.57.57.17) and it's been timed correctly. so an inlet valve will begin to open at 17' before top dead centre,  mark the front pulley at Top Dead Centre (my one has a small hole to align with the pointer on the timing cover), get the rocker cover off and get No 1 cylinder inlet valve fully open, then wind the engine back until the valve is closed, stick a 2 or3 thou' feeler gauge in the valve gap and slowly bring the engine round in normal running direction, when that feeler gauge goes tight you have gone through the clearance ramp and the valve begins to open, 

Ha Ha, should be 17' before TDC, on a Moss timing disc the distance between 0' and 17' is about an inch, and great difference here and you've either got a non standard cam, or the cam needs re-timing.            As I said this is a very unscientific, non engineering solution but can give you a simplified picture of what's going on.

Cheers Rob