Exhaust Manifold Glows red

[Julian Taylor_4995]

I have recently wrapped my cast iron exhaust manifold to keep the temperature under the bonnet cooler. The reason that this was a concern was that I have overheated the regulator on two dynamos. i have left a couple of gaps in the wrapping and after a run I can see that the manifold is glowing. 

The car hasn't been running well. Naturally i thought this was the cause. I have checked the ignition  timing and mixture and all seem to be correct. However the car lacks power and runs a hotter than normal.

I have noticed that there is an exhaust leak it is at the front of he system and it may well be the manifold - however i cannot find one. It is a cast iron manifold.

As the car is not running correctly I assume the excess heat is caused by the poor running. For the life of me I cannot find the issue but feel that it is running too lean - maybe by pulling in air from a damaged gasket. Any thoughts folks?

 

 it.

[ctc77965o]

Wow...never seen that on a TR

Looks very lean...could it be a fuel pump issue? Manifold leaks are normally worst at low power, as throttle opens and manifold pressure rises, they become a smaller contribution. If the fuel pump lacks flow, you can get a situation where at  idle all looks/sounds fine, but the engine goes lean under power simply because the pump cant keep up.

[Z320]

With the exhaust manifold wrapped or even with a heat shield it will be hotter itself.

This can cause damage on the exhaust material because it was never the plan to get it so hot.

[John Morrison]

Only ever seen this once ona TR4a, and the cause was way out ignition timing,

I'd check yours again.

John.

[Z320]

My advice:

wrap it off, look for damages and drive it again without wrapped

Why:

hotter manifold = hotter head = hotter valves

Edited July 25, 2022 by Z320

[Z320]

BTW allow me to ask: which regulator on the dynamo (has heat problems)?

Edited July 25, 2022 by Z320

[Jase]

Would you not swap out for a new more efficient manifold for safety reasons and then a good tune up?

[john.r.davies]

3 hours ago, John Morrison said:

Only ever seen this once ona TR4a, and the cause was way out ignition timing,

I'd check yours again.

John.

Plus one for John from me.   Too retarded, the charge is still burning in the manifold.    Could account for poor running too.

John (the other one)

[RogerH]

Hi Julian,

the standard exhaust manifold should run 'cooler' than the fancy fabricated pipes.  

I have never heard of s standard manifold getting so hot as to damage a dynamo regulator - they are quite substantial things.

Remove the wrapping.

Find out where the leak is and fix it.  The cast manifolds often crack where the branches jon near the down pipe.

Tune the spark timing

Tune the carbs

Report back

 

Good luck

Roger

[Z320]

Every engine throws out flames in the exhaust manifold, 

when you wrap it is likely it glows

 

Edited July 25, 2022 by Z320

[Phil Read]

I would check the ignition timing againg do it dynamically.

[Z320]

Some more thoughts:

not enouth valve clearance + insulation on the exhaust manifold causes 

manifold getting hotter —-> cylinder head getting hotter —> valves getting hotter and longer —-> less/ no clearance  —->exhaust valve not closed while working stroke —-> poor power and manifold getting more hot

 

Edited July 25, 2022 by Z320

[john minchin]

Assuming that the ignition timing is OK, I would check the cam timing as this is the only time that I have known a manifold to glow red. The one I observed was glowing red at idle, quite a surprise.

You can test for cam timing with Dial gauge indicators on a pair of pushrods and observing the markings on the front pulley.

Good luck,  John

 

[d2alfa]

I fitted an alternator some years ago and the recommendation in Roger Williams book is to fit a heat shield.

No problems.

David

[Andy Moltu]

I have seen my tubular manifold on the 6 glowing red whilst breaking a cam in. Didn’t notice it on the 4A but the manifold was well wrapped.

i don’t recall the timing or the fuelling being too far out. However we don’t often sit our cars at 2000rpm with the bonnet up for 20 mins. 

I should have looked when it was doing 6300rpm flat chat on the rolling road but I felt the need to go for a walk as it was scary  listening to it waiting for it to go bang. (Should have more faith in my own engine building)

[john.r.davies]

Julian,

John is referring to the cam timing method "Equal Lift on Overlap".

May I refer you to my article?   Equal Lift on Overlap - the other cam timing method - Technical Articles & Reviews - Sideways Technologies (sideways-technologies.co.uk)

And my more recent and simplified method: A new method of cam timing - Engine and Ancillary talk - Sideways Technologies (sideways-technologies.co.uk)

John

[Keith Wigglesworth]

I has this problem on the tubular manifold of my modified tr2 engine. It was resolved by advancing the ignition. The cam was too wild and I think added to the problem or maybe initiated it. The car would also run on badly until this issue was solved. Now permanently solved by a full rebuild with a sensible Newman PH1 cam. 
Keith

[Julian Taylor_4995]

Hi Folks 

Thank you so much for the sage replies. I haven't been ignoring you. I just haven't been able to look at the  car since i posted. A number of folk suggested ignition timing. Both at idled and of course to see if it was advancing and retarding as it should do. I made sure the the dwell was correct.

It is an interesting theory that Z320 floats about the fact that I have created the problem by wrapping the manifold. I think this is correct. What I have done is treated the symptom and not the cause. However there is still too much heat all I have done is confine it to the exhaust manifold.

On 7/25/2022 at 12:01 AM, ctc77965o said:

Wow...never seen that on a TR

Looks very lean...could it be a fuel pump issue? Manifold leaks are normally worst at low power, as throttle opens and manifold pressure rises, they become a smaller contribution. If the fuel pump lacks flow, you can get a situation where at  idle all looks/sounds fine, but the engine goes lean under power simply because the pump cant keep up.

This really struck a chord. I seemed to be able to get the car right at idle but then it wouldn't pull and vice versa i.e get it running well but then it was too rick at ldle

RogerH suggested a carb tune... well I thought I had done this this then I brought this issue up at work. My Boss is ex motor industry and rebuilds crashed cars for a hobby, His latest car is a recent Porsche four wheel drive with front near side damage and deployed airbags. He has a MK 1 GTi and a Porsche GT3, I think  he has done motor sport - Ergo he knows his way a car. He said the problem was probably old fuel as my car had been stuck and I needed to strip down the carbs. He was on the right track. However the problem was mechanical. How i missed the issue is a mystery. I can only say that it only became obvious with the crabs off the car. The butterfly spindle on carb No 1 was really badly warn, so bad that i had to check that it wasn't intentionally machined with a step in it! (please see the picture). What was even more surprising was the fact that the butterfly blade was loose. This meant that the whole spindle could move around - I am surprised the car ran.

I assume this is the issue and false or excess air was getting in when not needed as the spindle moved around. Not necessarily via the spindle shaft but just due to the butterfly never being quite where it should be on any given moment

I am surprised that all four plugs didn't were the same colour but then there is a balance tube on the inlet manifold so i guess the air balances out.

This paints a picture of a completely neglected carbs that haven't need looked at in 100,000 miles. the car was rebuilt in 2001 and due to my ( and my wife of course!) modest contribution to the worlds growing population, I have only done 15,000 miles, I really would not have expected this much wear

Thanks all for the responses, I will keep you posted

[john.r.davies]

Thank you, Julian!   So often the final diagnosis isn't  revealed, so when you tell us in detail, it adds to the knowledge base of all!

Well done!

John

[rcreweread]

Julian - if you are thinking of replacing your carbs, see my ad in Classifieds, link below:

https://www.tr-register.co.uk/classified/4816/H6-HS6-Stromberg-175CD-Carburettor-Sets-with-Manifolds-Linkages-Fully-Reconditioned-to-Concours-standard-For-Sale

Have also sent you a PM

Cheers Rich

[Julian Taylor_4995]

1 minute ago, rcreweread said:

Julian - if you are thinking of replacing your carbs, see my ad in Classifieds, link below:

https://www.tr-register.co.uk/classified/4816/H6-HS6-Stromberg-175CD-Carburettor-Sets-with-Manifolds-Linkages-Fully-Reconditioned-to-Concours-standard-For-Sale

Have also sent you a PM

Cheers Rich

Very reasonable too. However I have bought a bunch of spares,so in the short term I will rebuild by own to begin with. This cost £222 inc VAT and carriage so this looks like poor value next to your recon units

It may be I am wrong (with my diagnosis) but i doubt it. However come Christmas I may invest  - after all yours a bright and shiny.

 

 

[r-fox]

It seems the mixture is rather too rich at higher rpm hence leading on to an "post-combustion" of unignited excessive fuel in the manifold, therefore heating up to glow.

Maybe the following helps:

- advance the ignition to 20 - 22° at 1500 rpm

- install a Lambda-sensor right at the beginning of the single down-pipe or in case after the merger of the twin-downpipes to the single  exhaust pipe.

- Adjust the AFR at 3500 rpm to abt. 11.5  to  13.0 , that's the zone of best power performance.

   Find out the matching needle and adjust the carbs.

- Reconditioning of the carbs is certainly a good choice.

Hope this helps, good luck

 

Wolfgang