Well.......CAUSE FOUND!!!!
06-10-2009, 06:25 PM
#81
One thing possibly to note,
he says this is the first failure of its kind he has seen on a cvh.... then why would this one fail?? more likely the casting had an existing micro fracture/crack around this area made worse by the additional material removed... a machining error could also cause this, ie excessive weakening of the structure, just because he claims the bottom part doesn't actually hold the seat in doesn't mean its not an integral part of the casting structure, so removing too much material from this area would indeed weaken the side walls as well, potentially to the point of seat movement (when at operating temp) and hence failure.
second point that maybe worth noting... this failure as karl says is always due to heat. The two inner cylinders would be the hottest, so if your set up was very wrong (and the cause) i would have expected one of the inner (2 or 3) cylinders to have taken this damage, not the two outer and thus coolest. I can't see how the timing could be wrong or fueling wrong on this one cylinder? Again this points toward either a flaw in the casting or excessive material removed from this valve area. Remember this is done by hand and in many cases by eye..... an 1mm too much would make a massive difference to strength.
Rob,
he says this is the first failure of its kind he has seen on a cvh.... then why would this one fail?? more likely the casting had an existing micro fracture/crack around this area made worse by the additional material removed... a machining error could also cause this, ie excessive weakening of the structure, just because he claims the bottom part doesn't actually hold the seat in doesn't mean its not an integral part of the casting structure, so removing too much material from this area would indeed weaken the side walls as well, potentially to the point of seat movement (when at operating temp) and hence failure.
second point that maybe worth noting... this failure as karl says is always due to heat. The two inner cylinders would be the hottest, so if your set up was very wrong (and the cause) i would have expected one of the inner (2 or 3) cylinders to have taken this damage, not the two outer and thus coolest. I can't see how the timing could be wrong or fueling wrong on this one cylinder? Again this points toward either a flaw in the casting or excessive material removed from this valve area. Remember this is done by hand and in many cases by eye..... an 1mm too much would make a massive difference to strength.
Rob,
Last edited by Rob_DOHC; 06-10-2009 at 06:27 PM.
06-10-2009, 06:42 PM
#82
..BS Motorsport..
^ if you read what Karl has said though, the only way to port the head is to remove that small piece of material behind the seat, what other way is there around it?
06-10-2009, 09:53 PM
#83
Interesting points Rob!
I asked what is involved in repairing the head and got the following reply which I'm happy with.....
The chamber is welded over any area that is damaged, remachined to the same as the others and new inserts fitted. I think Newman has had quite a few problems with their solid lifters over the past few years and has kept changing the design to improve them, but unfortunetly it seems easier for them to blame the engine than sometimes admitting they’ve made an error. In general though their products are hard wearing, and the best of a bad bunch so you’re stuck with little option!
Oh, also to mention that it appears from a couple of your other pictures that your compression ratio looks near to standard. The ignition map you sent is wrong for a standard C.R engine, though I doubt that the ignition map alone contributed to the valve seat coming out. As said thermal expansion of the head (i.e. heat related) is the cause of valve seats falling out! It may be worth considering what AFR’s you were running at lighter throttle, as these engines benefit from running quite rich, so if you have been running at say 14.0 or leaner at lighter load, this could well be a contributing factor. Other issues to consider are the tappet gaps, as setting them incorrectly can cause thermal overload of the valve seat as proper valve seat contact is essential for heat conduction. Remember that the cold tappet setting is not necessarily correct for a hot engine because the CVH valves are VERY long and tend to expand considerably resulting in a tight tappet gap when the engine is hot. It is also important to run a very heavy valve spring as the CVH valve train is heavy (particularly the steel rockers) and requires a very stiff spring to keep the assembly under control and to keep the valve adequately closed, especially when under boost given the high exhaust back pressure you experience with a 0.36 turbine housing. The springs that Newman sell IF you have fitted them to your head are totally unsuitable, so I hope it still has the original std springs fitted that we built it up with. Although the seat came loose whilst driving steady it is probably a result of previous driving that has contributed rather than the exact driving conditions at moment of failure, but I will know more upon inspection.
Whatever the outcome of my inspection I will help you to fix this head as cheaply as possible, and will do the welding repair and machining for free for you to show good will, as I value all my customers and don’t like to see any engine failure where we have supplied parts. If I feel upon inspection that 8 larger inserts would be a good upgrade for this head, provided you are willing to pay for the larger seats, I will happily do the repair work and machining for free for you.
With regards to the block damage I would have your local machine shop fit a step liner to restore back to your original bore size, re-machine all your piston crowns by the same amount to remove any significant damage from No.4 piston, deck the block as appropriate for your chosen C.R and fit new rings if required to piston no.4.
Hope that helps,
Best regards,
Karl
Good customer service goes along way and he does not have to help me at all!
So it looks like i'll have my head back and not lost all the money that I spent on it, and hopefully the new seats will not be too expesive!
I asked what is involved in repairing the head and got the following reply which I'm happy with.....
The chamber is welded over any area that is damaged, remachined to the same as the others and new inserts fitted. I think Newman has had quite a few problems with their solid lifters over the past few years and has kept changing the design to improve them, but unfortunetly it seems easier for them to blame the engine than sometimes admitting they’ve made an error. In general though their products are hard wearing, and the best of a bad bunch so you’re stuck with little option!
Oh, also to mention that it appears from a couple of your other pictures that your compression ratio looks near to standard. The ignition map you sent is wrong for a standard C.R engine, though I doubt that the ignition map alone contributed to the valve seat coming out. As said thermal expansion of the head (i.e. heat related) is the cause of valve seats falling out! It may be worth considering what AFR’s you were running at lighter throttle, as these engines benefit from running quite rich, so if you have been running at say 14.0 or leaner at lighter load, this could well be a contributing factor. Other issues to consider are the tappet gaps, as setting them incorrectly can cause thermal overload of the valve seat as proper valve seat contact is essential for heat conduction. Remember that the cold tappet setting is not necessarily correct for a hot engine because the CVH valves are VERY long and tend to expand considerably resulting in a tight tappet gap when the engine is hot. It is also important to run a very heavy valve spring as the CVH valve train is heavy (particularly the steel rockers) and requires a very stiff spring to keep the assembly under control and to keep the valve adequately closed, especially when under boost given the high exhaust back pressure you experience with a 0.36 turbine housing. The springs that Newman sell IF you have fitted them to your head are totally unsuitable, so I hope it still has the original std springs fitted that we built it up with. Although the seat came loose whilst driving steady it is probably a result of previous driving that has contributed rather than the exact driving conditions at moment of failure, but I will know more upon inspection.
Whatever the outcome of my inspection I will help you to fix this head as cheaply as possible, and will do the welding repair and machining for free for you to show good will, as I value all my customers and don’t like to see any engine failure where we have supplied parts. If I feel upon inspection that 8 larger inserts would be a good upgrade for this head, provided you are willing to pay for the larger seats, I will happily do the repair work and machining for free for you.
With regards to the block damage I would have your local machine shop fit a step liner to restore back to your original bore size, re-machine all your piston crowns by the same amount to remove any significant damage from No.4 piston, deck the block as appropriate for your chosen C.R and fit new rings if required to piston no.4.
Hope that helps,
Best regards,
Karl
Good customer service goes along way and he does not have to help me at all!
So it looks like i'll have my head back and not lost all the money that I spent on it, and hopefully the new seats will not be too expesive!
06-10-2009, 10:21 PM
#86
That seems like a very fair reply to me...
I'm not disagreeing with that.. if you read what karl has said in his reply, damage as seen is caused by excessive heat, if this were the case i would have expected to see burnt valves or at least some kind of valve/valve seat damage to chambers 2 and 3... which from the pictures i cannot see.
But at the end of the day i am no cvh expert! lol
all the best karlos and glad they seem like a good bunch, it must be awkward in their position!
Rob,
^ if you read what Karl has said though, the only way to port the head is to remove that small piece of material behind the seat, what other way is there around it?
But at the end of the day i am no cvh expert! lol
all the best karlos and glad they seem like a good bunch, it must be awkward in their position!
Rob,
06-10-2009, 10:43 PM
#89
..BS Motorsport..
in ten years of fannying about with cars ive yet to come across anyone as genuine and helpful as NMS, just wish Id found them from the beginning instead of wasting thousands with wannabe tuners round our way!
07-10-2009, 03:13 PM
#91
Yes it is good new Fella's!
I'm not going bigger and better as money is really tight right now, i'm literally scraping enough to rebuild the bottom end and pay for the two new valves, and seats!
Karl suggested that I have them fit bigger valve seats but that is Ł200 so just having No.4 all repaired and sticking it straight back on.
Hopefully will be done in a week or two!
I'm not going bigger and better as money is really tight right now, i'm literally scraping enough to rebuild the bottom end and pay for the two new valves, and seats!
Karl suggested that I have them fit bigger valve seats but that is Ł200 so just having No.4 all repaired and sticking it straight back on.
Hopefully will be done in a week or two!
Last edited by Karlos G; 07-10-2009 at 03:56 PM.
07-10-2009, 03:37 PM
#92
Latest email.....
Since sending the last email I have received the head and had a decent inspection of it. Everything looks fine with regards to fixing the head, but I have noticed something of concern! The head gasket has not been sealing correctly, especially around the exhaust areas on the head, and the aluminium on the head where the head bolt flange pulls down on the head, is heavily fretted indicating the head bolts are not correctly holding the head down! I can tell from the area of fretting that when you fitted the head, you have NOT used the original head bolt washers which is essential in spreading the head bolt load. Can you please tell me what head gasket and bolts you were using? If you also look at the picture you sent me of your block face, it is VERY black and appears to be a poor sealing surface. The block head bolt thread holes are heavily corroded and full of rust which could have given a false torque reading when fitting the head, and should have been meticulously clean before fitting your new head!!! Proper head gasket sealing is essential in maintaining good cylinder head temperature and this could well be a significant factor in the cause of the valve seat falling out! It is essential that the block face is surface ground when building a new engine to ensure perfectly flat face, and that all bolt holes are clean and clear of debris.
To ensure a reliable fix I would certainly advise 8 larger inserts as we cannot be sure if the other seats are at risk, as this head has clearly been hot!
Regardless, I am happy to repair the chamber for you, so if you give me the go ahead I will fit 8 new seats, and two new valves for you. Cost for that will be Ł240 + your return postage.
Hope that helps and I await your info regarding the headgasket and bolts!
Best regards,
Karl
Since sending the last email I have received the head and had a decent inspection of it. Everything looks fine with regards to fixing the head, but I have noticed something of concern! The head gasket has not been sealing correctly, especially around the exhaust areas on the head, and the aluminium on the head where the head bolt flange pulls down on the head, is heavily fretted indicating the head bolts are not correctly holding the head down! I can tell from the area of fretting that when you fitted the head, you have NOT used the original head bolt washers which is essential in spreading the head bolt load. Can you please tell me what head gasket and bolts you were using? If you also look at the picture you sent me of your block face, it is VERY black and appears to be a poor sealing surface. The block head bolt thread holes are heavily corroded and full of rust which could have given a false torque reading when fitting the head, and should have been meticulously clean before fitting your new head!!! Proper head gasket sealing is essential in maintaining good cylinder head temperature and this could well be a significant factor in the cause of the valve seat falling out! It is essential that the block face is surface ground when building a new engine to ensure perfectly flat face, and that all bolt holes are clean and clear of debris.
To ensure a reliable fix I would certainly advise 8 larger inserts as we cannot be sure if the other seats are at risk, as this head has clearly been hot!
Regardless, I am happy to repair the chamber for you, so if you give me the go ahead I will fit 8 new seats, and two new valves for you. Cost for that will be Ł240 + your return postage.
Hope that helps and I await your info regarding the headgasket and bolts!
Best regards,
Karl
ths your every day car then
07-10-2009, 03:58 PM
#96
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Congratulations on being the first 
quite a mess it caused 
Re the above last correspondence I imagine you to be rather meticulous in your engine building Karl, hope you get it back together without too much grief
Zoe
quite a mess it caused Re the above last correspondence I imagine you to be rather meticulous in your engine building Karl, hope you get it back together without too much grief
Zoe
07-10-2009, 04:03 PM
#98
Payen HG and bolts.
Plan for mapping.... well TBH it seems less and less likely that it is the map that has anything to do with the failure, other experienced mappers have looked at my map and said it is perfectly fine, so as long as there is no Det, my EGT's are not too high and i'm not too lean I will carry on myself.
There is not a reputable Tuner local to me that will map MS, so I do not have a lot of choice even if I didnt want to do it myself.
Plan for mapping.... well TBH it seems less and less likely that it is the map that has anything to do with the failure, other experienced mappers have looked at my map and said it is perfectly fine, so as long as there is no Det, my EGT's are not too high and i'm not too lean I will carry on myself.
There is not a reputable Tuner local to me that will map MS, so I do not have a lot of choice even if I didnt want to do it myself.
07-10-2009, 08:32 PM
#102
Well i'm having the larger exhaust seats fitted now as if the head has got hot it will be that side that has suffered not so much the inlet, which is costing Ł125.
Just means my rebuild will take a bit longer as i'm poor now and cant get everything right away lol
Just means my rebuild will take a bit longer as i'm poor now and cant get everything right away
lol
07-10-2009, 10:07 PM
#103
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look on the bright side mate, winter is coming and the cabriolet would'nt be a lot of use now anyway. glad you have had some luck with the head.On the other hand, i do know where there is a 4wd cosworth for sale should you need 1.
13-10-2009, 09:32 PM
#108
Bottom end is stripped, flywheel, block, and crank are at my local engineers for skimming and inspection, head is being repaired!
Hopefully all back together by the end of next week!
Hopefully all back together by the end of next week!
When are you expecting your head back and how did they decide to repair it in the end?
Rob,
24-10-2009, 04:54 PM
#111
Yes mate it should be done any day, Karl emailed me Tuesday saying it should be ready Friday but he is really busy so might roll on a couple of days, as yet no word so i'm guessing it's not quite finished, I think he said it just needed the valves lapping in and then refacing.
Picked up a block today but there is a lip at the top of the bores so we'll see what my engineer says once it's been meassured as to whether it's any good or not, everything else I have here waiting to go together!
Oh and got the bits for my hydraulic clutch conversion now as well, so should have that all fitted as the engine goes back in!
Picked up a block today but there is a lip at the top of the bores so we'll see what my engineer says once it's been meassured as to whether it's any good or not, everything else I have here waiting to go together!
Oh and got the bits for my hydraulic clutch conversion now as well, so should have that all fitted as the engine goes back in!
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