Throttle sticking? Carb issue?

[Biggles]

I had a sub-optimal day today as I was supposed to be away for the weekend in my TR3 but he clearly had other ideas.

After about an hours driving I noticed that the revs weren't dropping reliably when I took my foot off the gas, with the result that I was somewhat rushing in to corners. The pedal didn't appear to be sticking and it wasn't happening all the time. I stopped and looked at the pedals and also the throttle linkage between the carbs. The pedal seemed to be moving freely and the linkage was returning to the stops ok.

I pressed on and there developed a loud and rather scary sounding tapping noise. Parked up, this only really happened at lowish revs (below 2500) and seemed to come from the front carb. 

Mr Google found a local garage and I popped in and they kindly had a quick look. The consensus was that the front carb was more open than the rear, that the link between them was a 'bit of a bodge' and that I'd be best driving home whilst I still could.

Driving home (about 2 hours), he was absolutely fine above 2500 revs - positively perky actually, but rattled away at junctions, though the surging revs seemed to have settled.

Attached is a picture of the link between the carbs. The breather hose tied out of the way with string is my roadside check that it wasn't fouling the throttle. I've attached a video (hopefully) so that you can hear the rattle too.

Here's a very brief video with the 'hiccup' sound - it sounds a lot worse when you're driving.

[BlueTR3A-5EKT]

Is it me?

Why are the carbs rigid mounted and not on sprung or flexible mounts?   With rigid mounting the float chambers are even more likely to froth.  What are the float levels set to?

Yes the interlink between the carbs would benefit from modification adding a flexible spring loaded  interlinking 

Good reading on Weber carbs in our Technical Bonanza that David Bee started.   The Terri Anne info is particularly useful 

 

 

[roy53]

Yes you need flexible mounts.

The interlink looks to be solid not alowing any adjustment between the 2 carbs to balance them. Do you not still have the over bar setup that comes with the manifold ?

Roy

[BlueTR3A-5EKT]

Bit like this

 

PS £2k buys these 42’s with other parts to fit.

 

[stuart]

You need these between carbs and manifolds https://www.dellorto.co.uk/shop/car-accessories/inlet-manifolds-and-fittings/manifold-accessories-and-fittings/misab-manifold-to-carb-mounting-plate/ and either Thackery washers and nylocs or the newer O ring and cup washers and nylocs to provide a bit of float to the mounting. To fit them your going to need a set of studs to go in the manifolds too. Whoever fitted your carbs doesnt seem to have done a very good job.

Stuart.

[Ralph Whitaker]

Is your front filter knocking on the inner wing?, there seems to be a chip on the paint at that point.

Ralph

[timhum]

The car is fitted with Jenvey Heritage Fuel Injection, not Webers.

[Ralph Whitaker]

8 hours ago, timhum said:

The car is fitted with Jenvey Heritage Fuel Injection, not Webers.

Never heard of that? very cleverly made to look like twin webbers.  So is that a high pressure common rail system with electronic control?

Ralph

[Motorsport Mickey]

On 9/30/2023 at 9:34 AM, BlueTR3A-5EKT said:

Bit like this

 

PS £2k buys these 42’s with other parts to fit.

 

That is a good price for the best performing size Weber for your TR AND includes all the inlets that runs you another £150 to get them on and running. What are they set up for Peter, 87mm pistons size ?

Mick Richards

[timhum]

1 hour ago, Ralph Whitaker said:

Never heard of that? very cleverly made to look like twin webbers.  So is that a high pressure common rail system with electronic control?

Ralph

It is and controlled by an Emerald ECU. Here's a link to the Jenvey and Emerald sites.

https://store.jenvey.co.uk/heritage

https://www.emeraldm3d.com/

Tim

[BlueTR3A-5EKT]

That explains the double ended fuel pipe.   One in then one return.

Engine needs a yoof or yoofess with a lap top not an old bloke or blokess with a spanner 

Edited October 3, 2023 by BlueTR3A-5EKT

[stuart]

2 hours ago, BlueTR3A-5EKT said:

That explains the double ended fuel pipe.   One in then one return.

Engine needs a yoof or yoofess with a lap top not an old bloke or blokess with a spanner 

Yep, all previous bets are off.

Stuart.

Edited October 3, 2023 by stuart

[RobH]

From the description of the rattle and the fast idle, I wonder whether one of the butterflies has somehow come adrift. 

[BlueTR3A-5EKT]

3 hours ago, Motorsport Mickey said:

That is a good price for the best performing size Weber for your TR AND includes all the inlets that runs you another £150 to get them on and running. What are they set up for Peter, 87mm pistons size ?

Mick Richards

Yes 87 mm.   Rolling road set for a TR Enterprises engine.

 

Also comes with

 

Edited October 3, 2023 by BlueTR3A-5EKT

[stuart]

On 9/30/2023 at 9:34 AM, BlueTR3A-5EKT said:

Bit like this

 

PS £2k buys these 42’s with other parts to fit.

 

Sooo tempted!

Stuart.

[Biggles]

Ok, thanks for all the suggestions. I managed to have another look this afternoon. The problem of the revs staying high doesn't appear to be there when he's cold or maybe it's gone away but the noise is still there.

I should have been more specific about his setup on the original post, sorry. I know that some of you have commented already, but Hoot's running Jenvey Heritage throttle bodies (which look like webers) and it's managed by an Emerald K6 ECU. I know about as much about these as I know about dentistry, but it does mean that there are no floats or choke.

I took the filters off today to see if I could track down the noise or at least eliminate some metal on metal movement. The sound appears to be air related, if that makes sense. I have attached another video with the filters off and the sound is quite clear. I don't think it's relevant, but oil pressure was 60 at idle and almost cold. The only other change I made this week was to change the radiator cap but for an identical unit (7psi).

There's another video below.

[stuart]

Thats popping back from one side of one throttle body. You need to talk to Emerald about that, they can probably sort it over the net if you can plug your laptop into the ECU.

Stuart.

[ntc]

1 hour ago, stuart said:

Thats popping back from one side of one throttle body. You need to talk to Emerald about that, they can probably sort it over the net if you can plug your laptop into the ECU.

Stuart.

Nope sounds like timing or spark issue to me.

[Nigel C]

5 hours ago, stuart said:

Thats popping back from one side of one throttle body. You need to talk to Emerald about that, they can probably sort it over the net if you can plug your laptop into the ECU.

Stuart.

+1 if its only on one set of inlets

[Biggles]

On 10/4/2023 at 11:07 AM, stuart said:

Thats popping back from one side of one throttle body. You need to talk to Emerald about that, they can probably sort it over the net if you can plug your laptop into the ECU.

Stuart.

I know this is an old thread, but I'm still working on this issue though it's not as bad as it was. I'm quoting the above from Stuart as I had Emerald on to the ECU last week.

The car did go away to my local motorsport specialist. He changed the plugs, changed the Ignition coil and checked the valve clearances. His view was that it was running lean, but he doesn't have a rolling road and there isn't one within an hour of here. He confirmed that the car seems to be pulling fine and he and I both think it's better than it was.

I then got my laptop connected to the ECU and Emerald very kindly did a remote. They made two changes, increasing the mixture slightly and enabling a setting that cuts the fuel when you come off the throttle. They have said that I'm welcome to call again, though it would be easier if they had the car with them in Norfolk (I'm in West Wales). I have taken the car out a couple of times to test and whilst it seems better, it's still popping back on deceleration and at idle. 

My chap said he couldn't find an air leak and the chap from Emerald said he thought that unlikely, but I guess I can't rule it out. What I find difficult is that something has happened to make it do this and I haven't been anywhere near the ECU map before I called Emerald.

Has anyone got any further ideas?

 

[stuart]

12 minutes ago, Biggles said:

I know this is an old thread, but I'm still working on this issue though it's not as bad as it was. I'm quoting the above from Stuart as I had Emerald on to the ECU last week.

The car did go away to my local motorsport specialist. He changed the plugs, changed the Ignition coil and checked the valve clearances. His view was that it was running lean, but he doesn't have a rolling road and there isn't one within an hour of here. He confirmed that the car seems to be pulling fine and he and I both think it's better than it was.

I then got my laptop connected to the ECU and Emerald very kindly did a remote. They made two changes, increasing the mixture slightly and enabling a setting that cuts the fuel when you come off the throttle. They have said that I'm welcome to call again, though it would be easier if they had the car with them in Norfolk (I'm in West Wales). I have taken the car out a couple of times to test and whilst it seems better, it's still popping back on deceleration and at idle. 

My chap said he couldn't find an air leak and the chap from Emerald said he thought that unlikely, but I guess I can't rule it out. What I find difficult is that something has happened to make it do this and I haven't been anywhere near the ECU map before I called Emerald.

Has anyone got any further ideas?

 

Have you tried a plug chop to see whats really going on with the mixture.

Stuart.

[Biggles]

Just now, stuart said:

Have you tried a plug chop to see whats really going on with the mixture.

Stuart.

Sorry - what's a plug chop?

[stuart]

1 minute ago, Biggles said:

Sorry - what's a plug chop?

Drive the car around for a few miles and when you see a convenient layby then switch off and coast in and then check the plug colours rather than allowing the engine to tick over, it gives you a better view of the engine pulling.

Stuart.