exhausting matters
Discussion
OK got new exhaust built a bit back + new gaskets supplied for LS7.
In an earlier thread I mentioned the manifold was blowing and asked if dry-fit was right as advised by the exhaust maker.
Now I think I know why:
The supplied gasket is D shaped as per head exhaust port, yet the manifild is cirular - there is not enough meat on the gasket D to make a true seal. Surely this is wrong?
Yes I could use sealer, but I would expect there is a better shaped gasket somewhere to do a proper job? But what and where from?
The original exhaust was trhe same round profile, and I had to seal that one.
Ideas please?
In an earlier thread I mentioned the manifold was blowing and asked if dry-fit was right as advised by the exhaust maker.
Now I think I know why:
The supplied gasket is D shaped as per head exhaust port, yet the manifild is cirular - there is not enough meat on the gasket D to make a true seal. Surely this is wrong?
Yes I could use sealer, but I would expect there is a better shaped gasket somewhere to do a proper job? But what and where from?
The original exhaust was trhe same round profile, and I had to seal that one.
Ideas please?
Thanks for all your comment guys. I have emailed the supplier/builder of the exhaust for his comments. Generally the job was exellent apart from this little hiccup.
I still would like to find the right sort of gasket for this myself, just in case - but google doesn't come up with much at all!
cheers
I still would like to find the right sort of gasket for this myself, just in case - but google doesn't come up with much at all!
cheers
OK, I measured both the inner pipe in the manifold and the outlet on the head and there is a 1mm diameter difference according to my gauge, so the match is not bad. I can easily chamfer the tube a tad to make it exact.
The overriding issue is then the gasket, and I have failed to find anything that migh fit the LS7 with a circular port profile!
What engines have the same port spacing?
Does any one know?
The overriding issue is then the gasket, and I have failed to find anything that migh fit the LS7 with a circular port profile!
What engines have the same port spacing?
Does any one know?
For those who are interested, after much googling and calls to GM builders and partsworld where I frankly got nowhere, and was getting rather frustrated as no-one would either comment or were able to advise... 
so after much
I got a cunning 
I went to the most obvious source - the factory themselves - well you would wouldn't you!
Problem solved - easily -
It appears that the Factory use a round profile gasket for their engines and exhausts!!!!!!!
...so I bought a set!
Easy when you know how!
so after much
I got a cunning I went to the most obvious source - the factory themselves - well you would wouldn't you!
Problem solved - easily -It appears that the Factory use a round profile gasket for their engines and exhausts!!!!!!!
...so I bought a set!
Easy when you know how!
No Paul,
These are brand new ones supplied by the exhaust builder as I said. If you look closely in the pics you will see where the O of the Ex flange plate meets the D of the gasket, and it is very clear that the bottom of the raised D in the Gasket is not getting compressed at all unlike the surrounding area. This leads to a weak spot at the bottom of the D, and so it blows as evidenced by the carbon deposits. Bit like fitting a square peg etc...
I know that many have been given D type gaskets, and most have got away with it, however with the very slightest variation in dimensions you would get a 'blow' unless youy are using copious amounts of sealant.
For me, once I realised the differences in the profiles, it was pretty clear that there would be a potential weakness.
Obviously the factory twigged this early on, and have moved to the correct Gasket profile for the flange - totally logical really, especially as the D profile on the head is totally inside the 'O' so-to-speak, thus a good seal!
These are brand new ones supplied by the exhaust builder as I said. If you look closely in the pics you will see where the O of the Ex flange plate meets the D of the gasket, and it is very clear that the bottom of the raised D in the Gasket is not getting compressed at all unlike the surrounding area. This leads to a weak spot at the bottom of the D, and so it blows as evidenced by the carbon deposits. Bit like fitting a square peg etc...
I know that many have been given D type gaskets, and most have got away with it, however with the very slightest variation in dimensions you would get a 'blow' unless youy are using copious amounts of sealant.
For me, once I realised the differences in the profiles, it was pretty clear that there would be a potential weakness.
Obviously the factory twigged this early on, and have moved to the correct Gasket profile for the flange - totally logical really, especially as the D profile on the head is totally inside the 'O' so-to-speak, thus a good seal!
Oh contrare, darlings!!
I bought my engine in 2007 from GM via JS, way before the factory started doing LS7's
As for the exhaust, well, it is stainless. I think the factory is mild steel from anecdotes here, or was.
If I am causing myself so much trouble, prey tell me why the factory uses 'O' profile gaskets, yet everybody (apart from the factory)seems to tell me that the 'D' profile is fine?
So are the factory wrong?
I am confused!
...and I am raising this, so that some others might just get some useful info - after all, isn't this forum all about giving and receiving for the common cause?
Problems are for solving... with a little bit of help from your friends!
If there were not problems to solve, it would be pretty boring!
I bought my engine in 2007 from GM via JS, way before the factory started doing LS7's
As for the exhaust, well, it is stainless. I think the factory is mild steel from anecdotes here, or was.
If I am causing myself so much trouble, prey tell me why the factory uses 'O' profile gaskets, yet everybody (apart from the factory)seems to tell me that the 'D' profile is fine?
So are the factory wrong?
I am confused!
...and I am raising this, so that some others might just get some useful info - after all, isn't this forum all about giving and receiving for the common cause?
Problems are for solving... with a little bit of help from your friends!
If there were not problems to solve, it would be pretty boring!
Edited by 3Dee on Saturday 25th August 18:30
I had the headers and cats zircoteked in silver, but after my wallet was raped for that exercise, decided to cover the centre-and rear boxes with silver-backed kevlar matt, and wrapped all the other pipes with Titanium-wrap, the latter is a not-unpleasing copper colour, very tough and even with one layer seems very effective.
The Zircotec does reduce the heat, but seemingly not as much as the other stuff I have used.
Currently I am carpeting the interior etc.
BTW, off-topic does anyone know of a clear spray or coating that can protect and harden a vinyl surface against scratches?
The Zircotec does reduce the heat, but seemingly not as much as the other stuff I have used.
Currently I am carpeting the interior etc.
BTW, off-topic does anyone know of a clear spray or coating that can protect and harden a vinyl surface against scratches?
Gassing Station | Ultima | Top of Page | What's New | My Stuff