Another one! Tap, tap, clack clack !!!
Discussion
justinp1 said:
If making a point that there is a design error is 'naming and shaming' then I think the same applies to every thread in the Speed Six Engine section...
No one was qualifying the point that there was design error, and that's my point. I get tired of TVR being slagged when if it was Joe Bloggs service agent or what ever, threads would have been closed.
There is a very fine line with name and shame, IMHO, I thought it was yet again crossed.
I dont want to hi-jack an excellent thread so lets just agree to disagree.
daftlad said:
If making a point that there is a design error is 'naming and shaming' then I think the same applies to every thread in the Speed Six Engine section...
No one was qualifying the point that there was design error, and that's my point. I get tired of TVR being slagged when if it was Joe Bloggs service agent or what ever, threads would have been closed.
There is a very fine line with name and shame, IMHO, I thought it was yet again crossed.
I dont want to hi-jack an excellent thread so lets just agree to disagree.
What the feck, you've bloody hijacked it as it is.
There aint no fine line, its just common sense, IF we were talking about a service company then yes, mentioning your negative experience is a form of naming and shaming because there are two sides to the story.
BUT
When you talk about an engine and a FACT like iron valve guides is a cheap and stupid way to cure a problem, thats a different ball game mate. There is no other side to the story, its an engineering principle, period.
This is the Speed Six Engine forum, so guess what? WE TALK about the engine, its good sides and bad sides.
And when someone like you comes along with a megaphone spirting out naming and shaming policies, just makes me cringe, that you cant see the difference between a technically dismissive post and an outright name and shame post.
Get a bleedin life and start submitting some technically debateable posts and cut this TVR representative crap. We're just here for one purpose, to learn and discuss. And this particular forum was created for the main purpose of sectioning speed 6 engine discussions away from the rest as too many have questions and it was blogging the other forums down. Join in, or butt out and stop yanking my nuts everytime I post.
SXS said:
justinp1 said:
If making a point that there is a design error is 'naming and shaming' then I think the same applies to every thread in the Speed Six Engine section...
No one was qualifying the point that there was design error, and that's my point. I get tired of TVR being slagged when if it was Joe Bloggs service agent or what ever, threads would have been closed.
There is a very fine line with name and shame, IMHO, I thought it was yet again crossed.
I dont want to hi-jack an excellent thread so lets just agree to disagree.
What the feck, you've bloody hijacked it as it is.
There aint no fine line, its just common sense, IF we were talking about a service company then yes, mentioning your negative experience is a form of naming and shaming because there are two sides to the story.
BUT
When you talk about an engine and a FACT like iron valve guides is a cheap and stupid way to cure a problem, thats a different ball game mate. There is no other side to the story, its an engineering principle, period.
This is the Speed Six Engine forum, so guess what? WE TALK about the engine, its good sides and bad sides.
And when someone like you comes along with a megaphone spirting out naming and shaming policies, just makes me cringe, that you cant see the difference between a technically dismissive post and an outright name and shame post.
Get a bleedin life and start submitting some technically debateable posts and cut this TVR representative crap. We're just here for one purpose, to learn and discuss. And this particular forum was created for the main purpose of sectioning speed 6 engine discussions away from the rest as too many have questions and it was blogging the other forums down. Join in, or butt out and stop yanking my nuts everytime I post.
Relax Ash ,
no ones intending to give you or anyone else a hard time, no meagaphone, just someone posting opinion. I'll take your advice, butt out and keep my opinions to myself in future as they based upon only my experience and are out of phase with a lot of whats been historically posted wrt the S6.
Carry on with all the excellent R&D work and I'll see you and the 1000bhp Cerb at CREAM.
Cast iron isn't so stupid a material to use - Rover / chevy / ford have all used it in the past
Note the use of the word 'past' I admit the bronze based alloys are far far superior materials for a guide per se. But if TVR are trying to beef up the already bendy valve stem due to the incorrect geometry then its not so stupid.
Of course the most sensible option would be to just correct the geometry but what do I know?
Matt
Note the use of the word 'past' I admit the bronze based alloys are far far superior materials for a guide per se. But if TVR are trying to beef up the already bendy valve stem due to the incorrect geometry then its not so stupid.
Of course the most sensible option would be to just correct the geometry but what do I know?
Matt
350matt said:
Cast iron isn't so stupid a material to use - Rover / chevy / ford have all used it in the past
Note the use of the word 'past' I admit the bronze based alloys are far far superior materials for a guide per se. But if TVR are trying to beef up the already bendy valve stem due to the incorrect geometry then its not so stupid.
Of course the most sensible option would be to just correct the geometry but what do I know?
Matt
You're right in respects to the aforementioned engines, but those stock ford/chevy/rovers dont rev up into the 7000rpm range and they're not DOHC either and not speed 6 engines
there was a whole load of technical stuff from melling and craft a while back... I'll see if I can get a quote from them to make things more interesting. An interesting point here:
Autobahn_forum said:
When a Porsche loses oil it is not past the rings, rather it is past the valve guides. Much like Ferraris and Lamborghinis, a Porsche has looser valve guide tolerances so as to have less valvetrain friction. Oil can get past that and ends up going out the tail pipe.
Right, spoke to them, and the upshot is, as long as cast iron guides are built to exacting specifications with thermal expansion properties taken into account then phosphor coated cast iron guides and valve stems also phosper coated/chromeflashed should be fine.
Its without a doubt a cheaper way of doing things, but cast iron guides do last longer than the other materials normally used in high end engines valve guides.
But 214N Stainless valves must be properly coated to make this work.
The only problem that could be an issue, is if the coating is of a poor grade or weak impregnation method and wears off rapidly, causing increased friction and wear'n'tear on the guides and valve stems.
So if you're gonna use iron guides, then things have to be done the right way and not the cheap way. Going down the bronze/berillium root is a more reliable way of knowing marginally when you'll need valve guides replaced, and they come as standard with more compliant thermal expansion properties than iron. Whence why their use is quite common in more modern engines today.
Its without a doubt a cheaper way of doing things, but cast iron guides do last longer than the other materials normally used in high end engines valve guides.
But 214N Stainless valves must be properly coated to make this work.
The only problem that could be an issue, is if the coating is of a poor grade or weak impregnation method and wears off rapidly, causing increased friction and wear'n'tear on the guides and valve stems.
So if you're gonna use iron guides, then things have to be done the right way and not the cheap way. Going down the bronze/berillium root is a more reliable way of knowing marginally when you'll need valve guides replaced, and they come as standard with more compliant thermal expansion properties than iron. Whence why their use is quite common in more modern engines today.
Oh nearly forgot, the main issue is the design apparently. The fact the development/research work was not done to find out WHY the bronze guides were wearing so quick, instead of going down the PROPER route, the quick fix was to throw in cast iron guides, which is a cheap way of sorting that problem out and doesnt sort out any inherent design flaws which can still lead to failures, so the valve guides will stand up, but the valves might not on extended friction etc.
Great forum, let's hope we can get the info we need.
My engine is having its head removed tomorrow (Tamora).
An exhaust valve was not closing so I took it to a local auto engineer,who has great deal of experiance with all types of engines, including racers. The valves were set up by a TVR main dealer (who I will not be naming) 4000 miles ago. They said that an exhaust valve was at its limit of shiming and that it would probably need sorting in the autumn. How right they were. The first job was to do a compression test, the results were alarming 1st cylinder 164psi, 2nd-230psi, 3rd-150psi, 4th-30psi (valve stuck open on this one),5th-140psi and 6th-135psi. Suspect no. 2 cylinder to be correct, or near enough. Conclusion is that it has been shimmed too tight, remember it was only shimmed 4000 miles ago!! The cover has been remove and lo and behold the engineer informs me what he suspected was correct, I don't have the clearances at the moment but can post them latter. The inlet cam is out of time by 2 degrees, assembly fault at TVR. His recomendations are to use new valves and springs from a German manufacture who specialise in racing valves, who's details I can get if any wants to know, and new valve guides. So far the fingers have not been inspected but hope this is done tomorrow.
Am I right in thinking that the shims are Peugot diesel? We think valve clearances are 0.006" inlet and 0.01" exhaust, does anyone have the correct figures?
Anybody got torgue figures yet?
I spoke to Autodata but they said TVR will not give them any information, suprise, suprise!
Anyway if things go to plan I will have saved a bit of money on the rebuild and not had to wait weeks/months for my car back.
My engine is having its head removed tomorrow (Tamora)
. An exhaust valve was not closing so I took it to a local auto engineer,who has great deal of experiance with all types of engines, including racers. The valves were set up by a TVR main dealer (who I will not be naming) 4000 miles ago. They said that an exhaust valve was at its limit of shiming and that it would probably need sorting in the autumn. How right they were. The first job was to do a compression test, the results were alarming 1st cylinder 164psi, 2nd-230psi, 3rd-150psi, 4th-30psi (valve stuck open on this one),5th-140psi and 6th-135psi. Suspect no. 2 cylinder to be correct, or near enough. Conclusion is that it has been shimmed too tight, remember it was only shimmed 4000 miles ago!! The cover has been remove and lo and behold the engineer informs me what he suspected was correct, I don't have the clearances at the moment but can post them latter. The inlet cam is out of time by 2 degrees, assembly fault at TVR. His recomendations are to use new valves and springs from a German manufacture who specialise in racing valves, who's details I can get if any wants to know, and new valve guides. So far the fingers have not been inspected but hope this is done tomorrow.
Am I right in thinking that the shims are Peugot diesel? We think valve clearances are 0.006" inlet and 0.01" exhaust, does anyone have the correct figures?
Anybody got torgue figures yet?
I spoke to Autodata but they said TVR will not give them any information, suprise, suprise!
Anyway if things go to plan I will have saved a bit of money on the rebuild and not had to wait weeks/months for my car back.
0.006" to 0.008 " inlet and 0.08" to 0.12 " exhaust. So a TVR mechanic told me. Good luck with it, can we have some pictures of what you have had done too?
It seems that TVR don't have any information on the speed six!!! Anyway I have a letter to say so.
Please, please TVR, release what information you have.
Interesting if the shims are Peugot diesel.
>> Edited by justinbaker on Thursday 22 September 18:11
It seems that TVR don't have any information on the speed six!!! Anyway I have a letter to say so.
Please, please TVR, release what information you have.
Interesting if the shims are Peugot diesel.
>> Edited by justinbaker on Thursday 22 September 18:11
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