seat recession

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mdt-son said:
Were exhaust valve seats fitted at the Norton-Villiers factory induction hardened?
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Possibly, but, from what I know (questionable information), induction hardening was done on cast iron heads beginning in the early 70's (or thereabouts), since it could be done in situ without the added expense of machining for seat inserts (like the Norton head). This gave us hardened exhaust seats in the parent metal. Once changing over from iron to aluminum, the seats can be made out of anything you like to reduce VSR, since you are now forced to go the route of machining for the individual seats.
 
I had backed away for a while as work was pretty far behind. That and some family health issues have been keeping me busy.

I don't know what the material in the original Fullauto seats is. It cuts like steel and is quite soft. It reminds me of the material used in the MK3-RH4 heads.
It tests at ~RHc 20 in the worn area.
seat recession


My cam profile is very soft on the closing ramp. The spintron shows no valve bounce with 110 lbs seat pressure at 7000 rpm. I find it hard to imagine that it is the source of the problem. But I will find out.

The seats in the Norton head were quite hard up to the last couple years of production and then they changed to a softer material. The later seats did wear a little faster than the old seats but neither of them were a problem with normal use.

None were induction hardened. That was used with integral seats in cast iron heads. Attempting to induction harden a seat in an aluminum head would not work as the seat would fall out after it cooled.

Of course a steel seat could be induction or case hardened in production before being ground to the final size. I don't know of any available.

I suspect the hard usage seen in my hot running oversized injected motor is more of an issue than the cam. The seats I installed are high nickel powdered iron seats that I have custom made. I have used them for many years with good results. Jim
 
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comnoz said:
The seats in the Norton head were quite hard up to the last couple years of production and then they changed to a softer material. The later seats did wear a little faster than the old seats but neither of them were a problem with normal use. Jim
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I always appreciate that you make an effort to answer the obvious questions without them having to be asked...
 
comnoz said:
I don't know what the material in the original Fullauto seats is. It cuts like steel and is quite soft. It reminds me of the material used in the MK3-RH4 heads.
It tests at ~RHc 20 in the worn area.
Jim
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Isn't Cheddar around RHc 4 ? ... concerned in Australia.
 
I wonder if there is any difference in the seat hardnesses between that first run with #8 and the last(ish) runs with your #170 (and mine is #172)?
 
In 2004 McDougall removed the bronze seats in my Vin as he said they wouldn't stand up with unleaded fuels.
He had an 8' long bar of Austenitic Iron that he used to cut new seats from.
Those seats looked almost unchanged at 55,000 miles, seems to be tough stuff.
Ive heard others say that the bronze seats have worked fine with unleaded fuel, but they only are doing a few hundred miles per year, so it's no test.

Glen
 
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worntorn said:
In 2004 McDougall removed the bronze seats in my Vin as he said they wouldn't stand up with unleaded fuels.
He had an 8' long bar of Austenitic Iron that he used to cut new seats from.
Those seats looked almost unchanged at 55,000 miles, seems to be tough stuff.
Ive heard others say that the bronze seats have worked fine with unleaded fuel, but they only are doing a few hundred miles per year, so it's no test.

Glen
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Yeah, I always used bronze or copper/beryllium seats in my racebikes.

I tried bronze in my streetbike once and found the seats got wide pretty quickly so I went back to iron.

I would do copper/beryllium if I could find a good source anymore. That stuff is great.
 
gortnipper said:
I wonder if there is any difference in the seat hardnesses between that first run with #8 and the last(ish) runs with your #170 (and mine is #172)?
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I can certainly do without the drama of valve seats so we will hope for the best.

The head off my 110 mm bore DR (air/oil cooled) head is away now at Phil Tainton Racing having seats fitted for 4 mm over size valves and there was some concern to how long they will last (KibbleWhite seats Alu/Bronze ? and valves)
I do know the stock OEM valves and seats in that bike had done some very hard work but the seats faces still looked good with no real leakage but seem to remember they are hardened and any refacing on them would do more harm than good to the hardened surface.

Back in NZ in the 1990's we still had Leaded Super grade fuel and engines ran well with a nice grey exhaust including my 13.7/1 9000rpm 80+rwhp beveldrive desmo Ducati.. It never missed a beat in 20000 kms (12000 miles) after the engine was built, when that fuel was phased out and unleaded (with high aromatics) was introduced it was all down hill. (There was no indication of the need to rejet and the chambers had a sticky gooey build up)
The original OEM valves seats (bronze?) had been replaced with iron of some sort and even those receded where there had been none in all those kms on leaded fuel, even worse was the rings were replaced twice in the next 7000 kms and I had even resorted to those canisters in the fuel lines which contained magic metal impregnated with fairy dust but they still failed, try 0.5 mm end gaps out to around 3 mm on the oil rings and high (oil) consumption with no visible smoke.... That fuel was eventually replaced after with no accountability from the fuel companies, it was so toxic some older cars were catching on fire after fuel lines failed.. I went to even harder seats and octane boosters or 105 leaded race fuel.. Fuel should not be a problem these days you would think even in an air cooled engine which will do it a little tougher than WC.
 
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Well curiosity got the best of me. I pulled a seat from a new FA head #205
It is LF in the picture.

Looking at the fracture it looks like some type of iron. It breaks without bending first but it's a little finer grained than the second seat which is removed from an RH4 head. Both seats are too soft to get a C scale reading but a file tells me the FA seat is slightly harder than the MK3-850 seat.

The seat at the left rear is one of the high nickel iron seats I have made. It is hard with a reading of 45 RHc.

The right rear seat is a Kibblewhite universal nickel/iron seat. It tests at 35 RHc.

My seat and the Kibblewhite seats both bend a little before breaking.

I don't have any earlier model stock seats to test at this time.
seat recession
 
Are we looking to hard here for culprit other than the valve set itself - the recession looks regular and affects both sides to a similar degree. To affect both sides discounts any errors in engine build, but not valve seat manufacture where it could have missed HT stage, we are also assuming this is the first instance of this with a FA head, it would be too early to say one way or another.
The valve seat is not clever enough to know what cam is fitted, but how the valve comes onto the seat could be a cause though surely it would need to be massively different to the many other cams out there to cause this recession, so this is also unlikely. Maybe there is more than one issue here, of which neither are likely to be identified.
Will check my clearances this weekend.
 
comnoz said:
Basically the same as a Webcam 86c when run with radius followers.
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Only on lift with the PW4 lifting an additional 0.5mm at the valve, the rest is massively different, including a far wider LSA. With the 150mm radiused followers it can easily be used on the road and starts easily. Some have said it should not even work, but it does. I have uploaded my Dyno result of it on another thread, and this is with a standard 850 FA head and a compression plate fitted running real rich to boot, the silencers were straight through un-fluted. The 86c timing looks far more ferocious.
I shall get some ground up and on the market, currently only 5 exist, the boss has 2, Norman White has one fitted and running and myself, plus one spare. If anyone wants to try it come to the openday - for those that like the sound of the PW3 and think this will sound the same will be massively disappointed.
 
I suspect the failure is due to the hard use they see in my bike.

The seats should hold up as well as the stock seats did in the original head -but then I had to replace the seats in my original head 30 some years ago.
 
Madnorton said:
Only on lift with the PW4 lifting an additional 0.5mm at the valve, the rest is massively different, including a far wider LSA. With the 150mm radiused followers it can easily be used on the road and starts easily. Some have said it should not even work, but it does. I have uploaded my Dyno result of it on another thread, and this is with a standard 850 FA head and a compression plate fitted running real rich to boot, the silencers were straight through un-fluted. The 86c timing looks far more ferocious.
I shall get some ground up and on the market, currently only 5 exist, the boss has 2, Norman White has one fitted and running and myself, plus one spare. If anyone wants to try it come to the openday - for those that like the sound of the PW3 and think this will sound the same will be massively disappointed.
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The 386c lobe is the same as the intake lobe on the 2S combat cam.

When you use that profile with a radius follower you get a less "ferocious" lift rate. The 86c cam is ground with tighter lobe centers for more midrange hit.

Of course with more overlap the 386c cam is going to be more sensitive to the exhaust tuning.
 
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