Starting to get a bit hot under the bonnet
Discussion
Hi all,
Well, my car is nearing completion and should hopefully be back with me in the next few weeks
Thought I'd add a shot of some hot pipes and a video or two
A video... or three
A bit ill
On the rollers
Up tdhe road
Well, my car is nearing completion and should hopefully be back with me in the next few weeks
Thought I'd add a shot of some hot pipes and a video or two
A video... or three
A bit ill
On the rollers
Up tdhe road
Edited by NickM450 on Saturday 27th September 20:15
NickM450 said:
Hi all,
Well, my car is nearing completion and should hopefully be back with me in the next few weeks
Thought I'd add a shot of some hot pipes and a video or two
While this looks impressive, I'm sorry to say Nick but it's not good at all Well, my car is nearing completion and should hopefully be back with me in the next few weeks
Thought I'd add a shot of some hot pipes and a video or two
Edited by NickM450 on Saturday 27th September 20:15
The only way your manifolds should ever glow red like that is if:
A: You have a huge restriction in the exhaust
B: You have a turbo
C: Your valve timing is well out (new cam and the fitter didn't dial it in correctly)
D: You have adjustable valve gear and or push rods, and these have been adjusted incorrectly
E: Your suffering massive over fueling
F: Your ignition timing is massively out
G: You have an ignition issue causing incomplete combustion
Obviously none of the above are good.
That's a big list but if you asked me to guess what your particular issue was from just looking at your photos I'd put money on over tight valve clearances, I say this because each individual header pipe appears to be glowing at the same rate and the engine does not appear to be misfiring or producing black smoke (unburnt fuel) in your other videos.
This is a bit odd as the Rover V8 uses hydraulic followers which are self adjusting
When the valve clearances are set too tight on an OHV engine with adjustable valve gear the valves will still remain slightly open as the followers are on the heel of the cam lobes, at this point your valves should be very much firmly shut!
If exhaust valves aren't being allowed to close fully and seal against the valve seats (because valve clearances are set too tight) compression gasses and unburnt fuel is allowed past the slightly open exhaust valve.
If the exhaust valves are always slightly open during all four cycles fresh fuel and air from the induction stroke will pass into the exhaust manifold as the crank passes BDC and the pistons start to rise in the bores on the compression stroke (before your ignition system has initiated the burn).
All that fresh fuel and air passes the slightly open exhaust valve that should be firmly shut, this combustible mixture enters the exhaust manifold which has been super heated by the combustion gasses that leaked passed the slightly open exhaust valve on the power stroke.
The super heated exhausts manifold is so hot this fresh air and fuel that leaks passed the valve starts to burn where it shouldn't causing the manifolds to glow cherry red like a pot belly stove.
Valve clearances that are set too tight are a very very bad thing indeed, in no time at all those hot combustion gasses will slice through your exhaust valves like a cutting torch.
On the other hand if valve clearances are set too loose all you'll find is they'll make an annoying tapping noise and you'll not be achieving absolute optimum performance.
If the tappet taps at least you know the valve is closing fully and you're not destroying your valves, that's why a noisy tappet is a happy tappet
Your situation is confusing me though as the Rover V8 has hydraulic self adjusting tappets, so the valve will always shut & seal nicely
Do you have adjustable push rods by any chance???
If so you need to remind whoever set them up that a noisy tappet is a happy tappet before the over tight valve clearances destroy your valves
And finally (unsurprising) if the valve clearances are set correctly and your valves close properly you'll make a shed load more power and double your fuel economy at the same time
lots of helpful info there from Chimpongas, I remember my ajp manifolds glowing when Joolz was mapping the griff on his dyno, but not to this extent, they can get extremely hot when mapping the engine under load, sort of simulating the car going flat out up a steep hill, but yours do look a tad excessive, was the chap mapping under load when this pic was taken?
most manifolds will glow like this but you never get to see it unless its being worked under load on a dyno, a normal power run would not be the same as under load mapping use.
most manifolds will glow like this but you never get to see it unless its being worked under load on a dyno, a normal power run would not be the same as under load mapping use.
Edited by clive f on Monday 29th September 10:20
Stainless steel glows dull cherry red like the pictures at around 1472 degrees Fahrenheit.
I run EGT sensors in my manifolds which are an excellent tuning aid BTW, but even holding a fixed high load site on the rollers for sustained period I have never seen my manifolds go over 1160 degrees Fahrenheit which is still a long way off even the first signs of faint red which will typically start to appear around 1300F.
Sorry but something is wrong here, if I saw that on any other engine I'd immediately say the valve clearances have been set too tight so it's very odd on to see it on a Rover V8 which has self adjusting hydraulic tappets
Can we conform if the OP is indeed running solid lifters and adjustable rockers (or push rods) as I suspect, or if they are the standard hydraulic lifters in there?
Whatever the answer, glowing exhaust manifolds like that are an indication that something is not right, unless that is we're talking about a serious race engine under load on an engine dyno or one fitted with a turbo.
Watch your exhaust valves OP, you could be in for a big bill with glowing manifolds like that!
I run EGT sensors in my manifolds which are an excellent tuning aid BTW, but even holding a fixed high load site on the rollers for sustained period I have never seen my manifolds go over 1160 degrees Fahrenheit which is still a long way off even the first signs of faint red which will typically start to appear around 1300F.
Sorry but something is wrong here, if I saw that on any other engine I'd immediately say the valve clearances have been set too tight so it's very odd on to see it on a Rover V8 which has self adjusting hydraulic tappets
Can we conform if the OP is indeed running solid lifters and adjustable rockers (or push rods) as I suspect, or if they are the standard hydraulic lifters in there?
Whatever the answer, glowing exhaust manifolds like that are an indication that something is not right, unless that is we're talking about a serious race engine under load on an engine dyno or one fitted with a turbo.
Watch your exhaust valves OP, you could be in for a big bill with glowing manifolds like that!
Thanks guys, got me slightly worried now though 
When the photo was taken it was mid-run under load and half way through a mapping session, not a power run. There was also black smoke from time to time as the chap adjusted the map.
The followers and pushrods have just been replaced with standard stuff, Big Col advised against keeping my adjustables and solid lifters, cam was done last year.
I thought it was normal and just impressed by the light show, whoops!
When the photo was taken it was mid-run under load and half way through a mapping session, not a power run. There was also black smoke from time to time as the chap adjusted the map.
The followers and pushrods have just been replaced with standard stuff, Big Col advised against keeping my adjustables and solid lifters, cam was done last year.
I thought it was normal and just impressed by the light show, whoops!
rigga said:
Well that explains it as it was mid mapping and the fueling was not optimal.
What he said, panic over.Sounds like overfueling under load while mapping, I'm sure your mapper has corrected it now and with hydraulic followers the valves should be firmly shutting.
Enjoy, and apologies if I scared you there.
Overfueling won't cause the exhaust to glow but a very lean mix will, but my bet would be on retarded ign timing for the conditions if the engine is not under load and on fast idle thus creating this condition your hardly going to be able to recreate this condition when the car is driving i.e under load.
Sardonicus said:
Overfueling won't cause the exhaust to glow but a very lean mix will, but my bet would be on retarded ign timing for the conditions if the engine is not under load and on fast idle thus creating this condition your hardly going to be able to recreate this condition when the car is driving i.e under load.
My money is on setting the ignition right... if its not advancing enough, the ignition/flame will still burn when the ex valve opens and out in the exhaust... am I wrong?"my bet would be on retarded ign timing for the conditions"
This would have been my guess also, its how the rally boys keep their turbos spooled up when not under power (anti lag) The late burn caused by the late spark carries on into the exhaust after the exhaust valve opens at the bottom of the power stroke.
This would have been my guess also, its how the rally boys keep their turbos spooled up when not under power (anti lag) The late burn caused by the late spark carries on into the exhaust after the exhaust valve opens at the bottom of the power stroke.
Especially ChimpOnGas, such excellent contributions are the reason we're all here, even if they do sometimes scare the bejesus out of us 
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