Irony
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| posted on 24/7/14 at 07:47 AM |
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Stainless Exhaust Discolouring Time Rover V8
Started my engine for the first time recently and the exhausts get bloody hot! I ran it last night for maybe 10 minutes max and I can already start
to see my nice new shiny stainless exhausts beginning to discolour! In fact I have been having ignition issues and two cylinders where not working
properly and they haven't discoloured as much.
Is this normal??
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BaileyPerformance
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| posted on 24/7/14 at 07:56 AM |
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Did you sort out why it was idling rough? (Re your previous topics)
It is normal to get hot headers that will discolour, the temperature of the headers are directly effected by the ignition timing - retarded timing
will increase temperature.
Also, incorrect valve clearances or lifter pre-load will cause hot headers as well as rough running.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Irony
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| posted on 24/7/14 at 08:04 AM |
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quote:
Originally posted by BaileyPerformance
Did you sort out why it was idling rough? (Re your previous topics)
It is normal to get hot headers that will discolour, the temperature of the headers are directly effected by the ignition timing - retarded timing
will increase temperature.
Also, incorrect valve clearances or lifter pre-load will cause hot headers as well as rough running.
I seem to have cured a lot of the problems thanks to yours and others advice. I think I had the timing out by 10 degrees and the normal ignition
cable wrongly placed issue. I fabricated a new better VR sensor bracket and redid the timing at the toothed gear. I changed the ignition cables
about and it runs a lot better now.
I was led to believe that the lifter preload is not that critical when using a standard cams. I have not done anything about it as it looks a bit of
a pig to do.
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40inches
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| posted on 24/7/14 at 08:16 AM |
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My headers have turned brown, right to the silencer It polishes out easily enough, but I only bother with the exterior bits.
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Irony
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| posted on 24/7/14 at 08:18 AM |
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quote:
Originally posted by 40inches
My headers have turned brown, right to the silencer It polishes out easily enough, but I only bother with the exterior bits.
I was expecting it to happen eventually - maybe after the first proper run out. But after 10 minutes seems a bit quick.
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40inches
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| posted on 24/7/14 at 08:43 AM |
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quote:
Originally posted by Irony
quote:
Originally posted by 40inches
My headers have turned brown, right to the silencer It polishes out easily enough, but I only bother with the exterior bits.
I was expecting it to happen eventually - maybe after the first proper run out. But after 10 minutes seems a bit quick.
Mine turned brown almost immediately too. I was expecting them to turn blue lol
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Andy S
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| posted on 24/7/14 at 11:40 AM |
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Just Google steel temperature colour chart - colouring is temperature dependent not time. Putting a mirror polish finish makes it look better when it
colours and holds off the oxides.
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coyoteboy
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| posted on 24/7/14 at 12:11 PM |
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From http://www.bssa.org.uk/topics.php?article=140
quote:
The table below represents the temper colours that are likely to form on stainless steel type 1.4301 (AISI 304) if heated in air.
THIS INFORMATION MUST BE USED WITH CARE WHEN INTREPETING THE HINT TINT COLOURS OBSERVED ON STAINLESS STEEL SURFACES AS THE HEATING CONDITIONS ARE NOT
SPECIFIED.
Colour Formed Approx Temperature C
pale yellow 290
straw yellow 340
dark yellow 370
brown 390
purple brown 420
dark purple 450
blue 540
dark blue 600
My stainless downpipe has never gone past purple brown, but it is post-turbo.
[Edited on 24/7/14 by coyoteboy]
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Irony
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| posted on 24/7/14 at 01:03 PM |
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I can safely say they are pale yellow at the moment. I just didn't think it happened almost immediately.
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BaileyPerformance
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| posted on 24/7/14 at 05:50 PM |
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I was led to believe that the lifter preload is not that critical when using a standard cams. I have not done anything about it as it looks a bit of
a pig to do.
If your running a stock cam, and the block and/or heads have not been machined heavily then you'll be fine.
If its a TVR engine they tend to machine alot off the heads to get the CR up and so install shims under each rocker post to bring pre-load back up.
(without these shims you can get lifter jackup causing the valve to not completely close)
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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richardm6994
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| posted on 24/7/14 at 05:57 PM |
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Mine went pale yellow almost instantly but haven't got any worse since.
http://s1060.photobucket.com/user/richardm6994/media/photoshoot/Detail-06_zpsefc37299.jpg.html
[Edited on 24/7/14 by richardm6994]
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