One for Clive/Richard I would imagine.
The restoration of my collection of MT machines has been going well. However, a 3hp B&S which would fire but not run revealed damaged valve seats which needed recutting. This would complete a very nice rotovater.
I had access to a wonderful little local outfit that did a previous engine for £5.
They've gone down the tubes & there is no-one in the vicinity that does this service.
Any advice? (North. Oxon.)
Valve seat cutting.
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Clive.
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Hello Tel,
Believe it not I have never used a valve seat cutter.!!
Have ground in plenty of valves with paste including new valves when replacing those that had been very burnt into..but never had to use a seat cutter..
And sadly not having come through an apprentice scheme...never even got to seat cut at college either..!!
So I'm not being very helpful today..
All the best,
Clive
Believe it not I have never used a valve seat cutter.!!
Have ground in plenty of valves with paste including new valves when replacing those that had been very burnt into..but never had to use a seat cutter..
And sadly not having come through an apprentice scheme...never even got to seat cut at college either..!!
So I'm not being very helpful today..
All the best,
Clive
Hello Tel
Interested to hear that you are restoring an MT.
I know that this is a bit off topic but can you give me a few hints and tips about painting the metal work on these machines please? Mine is still going strong but is showing a lot of rust in places. Is it just a matter of rubbing it down and giving it a coat of Hammerite.
John
Interested to hear that you are restoring an MT.
I know that this is a bit off topic but can you give me a few hints and tips about painting the metal work on these machines please? Mine is still going strong but is showing a lot of rust in places. Is it just a matter of rubbing it down and giving it a coat of Hammerite.
John
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Clive.
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Hello Tel,
The old book of words that I have on B&S says that valve seats can be replaced on aluminium engines and shows a range of special tools to achieve it... again, I have never done it...and quite how well the original would pull out the alu' without it splitting away the peened over section that holds it in place
and just how well the peening with a punch could be achieved once a new one was pressed in I'm not sure. 
All the best,
Clive.
The old book of words that I have on B&S says that valve seats can be replaced on aluminium engines and shows a range of special tools to achieve it... again, I have never done it...and quite how well the original would pull out the alu' without it splitting away the peened over section that holds it in place
and just how well the peening with a punch could be achieved once a new one was pressed in I'm not sure.
All the best,
Clive.
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Clive.
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Hello Johnboy,
...I was thinking that.. but only in fact answered the technically possible bit..!!
In reality the reason why I have never come accross the operation is that working on a customers engine with a mounting bill it would be the case that by the time such fitments were needed that the rest of the engine would doubtless be poorly elsewhere.. the oft' taken route was a short engine when still available...or new.
Different of course when time is free and it is a labour of love...but still think that it's a job that would end in tears.
That'll be 3 days with the grinding paste then Tel. !!
All the best,
Clive.
...I was thinking that.. but only in fact answered the technically possible bit..!!
In reality the reason why I have never come accross the operation is that working on a customers engine with a mounting bill it would be the case that by the time such fitments were needed that the rest of the engine would doubtless be poorly elsewhere.. the oft' taken route was a short engine when still available...or new.
Different of course when time is free and it is a labour of love...but still think that it's a job that would end in tears.
That'll be 3 days with the grinding paste then Tel.
!!
All the best,
Clive.
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Richard
Hello Tel & Clive
Regrinding a valve with paste is OK for a de-coke but a burnt seat is a different proposition. The new valve is not certain to be the right length anyway. I use a Woolf and Black & Dekker vibro-centric valve and seat cutter on my machines. The system was devised when de-cokes were common on cars and the side valve Ford had non-adjustable valves the same as modern Briggs Strattons. Vibro-centric machines make very little when a garage is sold up but few mechanics know how to use them. There should be a local engine builder who can do the job, small garages, or failing that a local car restorer is sure to know of one.
Regards Richard
Regrinding a valve with paste is OK for a de-coke but a burnt seat is a different proposition. The new valve is not certain to be the right length anyway. I use a Woolf and Black & Dekker vibro-centric valve and seat cutter on my machines. The system was devised when de-cokes were common on cars and the side valve Ford had non-adjustable valves the same as modern Briggs Strattons. Vibro-centric machines make very little when a garage is sold up but few mechanics know how to use them. There should be a local engine builder who can do the job, small garages, or failing that a local car restorer is sure to know of one.
Regards Richard
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Clive.
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Hello,
An interesting sounding device Richard...and as you can gather we didn't have one.!!
I can recall seeing a chunky cast contstruction, grey chipped paint, covered in grime B&D badged machine sat in the far corner of a workshop with assorted size grinding wheels..is that the B&D machine.?? I would be interested to see a photo of the device.
Undoubtably it sounds the machine to have to give the correct face angles.. as iregularity of the face would not be corrected by paste grinding.. only mirrored on the valve.? and a shape irregularity to the valve could I summise be the hot spot to start another burn.
I am keen to know the actual damage/wear pattern on the valve seats Terry...out of curiosity, as it still remains that in my previous work I have generally not come across an otherwise servicable engine that valves would not grind in with paste to give a good seal...and they have to seal 100% as without they will not start/run...there are no other good cylinders there to carry along a poorly one.
B&S engines set weak or running weak due to another ailment would burn a chunk out of the valve face but mostly I found the seats remained servicable...
A new valve being manually gapped with material removed from stem finally using a honing block, with holes to suit various sized valve stems, keeping the base of the stem true...then ground in with further gap adjustment as required.
By the time an engine was brought in it was mainly either restorable easily with hand tools or if it had been forced to run and run in an ever increasing poorly condition that is when other damage had been done upsetting the viabilty/practicality of a repair.. On aluminium engined rotary mowers blocked cooling causing overheating warpage leading to a slightly leaking head gasket was favourite causing burn to cylinder block threads and warpage between bolts...with damage increasing with each running period. I have a feeling that this warpage remains mobile once established. In some cases the exhaust valve corner would have "tipped" away from the cylinder. Low oil all then adds to this often leading to the flywheel side bearing picking up first..which I have caught early and cleaned quite ok.. but not if further runs have already been made worsening the damage.
There was another damage catagory.. that was the inflicted in service or repair damage and sometimes not admitted to. They could be a fascinating unknown to look at. Suffolk A98 crankshaft ends were a sad classic one here...clunk ...oh, left hand thread .
B&S engines can though continue well past book figure wear...I have run and operated quite satisfactorily B&S engines with non viably correctable wear...one being a 3.5hp on a Marquis which had "one final repair" by the local agent 15 years ago. It has wear on the exhaust valve guide that has to be seen to be believed.. but on it goes, slow reving and with a large additional flywheel helps I'm sure, but the valve still seals or it would not pump fuel up and draw it to start ok and run and does a days work every fortnight quite ok.."touchwood"
Perhaps you should arange a swop for that mighty 2 sroke rotavator that you saw on your holiday travels Terry.
I hope you can get the job beaten and back to good health.
All the best,
Clive.
An interesting sounding device Richard...and as you can gather we didn't have one.!!
I can recall seeing a chunky cast contstruction, grey chipped paint, covered in grime B&D badged machine sat in the far corner of a workshop with assorted size grinding wheels..is that the B&D machine.?? I would be interested to see a photo of the device.
Undoubtably it sounds the machine to have to give the correct face angles.. as iregularity of the face would not be corrected by paste grinding.. only mirrored on the valve.? and a shape irregularity to the valve could I summise be the hot spot to start another burn.
I am keen to know the actual damage/wear pattern on the valve seats Terry...out of curiosity, as it still remains that in my previous work I have generally not come across an otherwise servicable engine that valves would not grind in with paste to give a good seal...and they have to seal 100% as without they will not start/run...there are no other good cylinders there to carry along a poorly one.
B&S engines set weak or running weak due to another ailment would burn a chunk out of the valve face but mostly I found the seats remained servicable...
A new valve being manually gapped with material removed from stem finally using a honing block, with holes to suit various sized valve stems, keeping the base of the stem true...then ground in with further gap adjustment as required.
By the time an engine was brought in it was mainly either restorable easily with hand tools or if it had been forced to run and run in an ever increasing poorly condition that is when other damage had been done upsetting the viabilty/practicality of a repair.. On aluminium engined rotary mowers blocked cooling causing overheating warpage leading to a slightly leaking head gasket was favourite causing burn to cylinder block threads and warpage between bolts...with damage increasing with each running period. I have a feeling that this warpage remains mobile once established. In some cases the exhaust valve corner would have "tipped" away from the cylinder. Low oil all then adds to this often leading to the flywheel side bearing picking up first..which I have caught early and cleaned quite ok.. but not if further runs have already been made worsening the damage.
There was another damage catagory.. that was the inflicted in service or repair damage and sometimes not admitted to. They could be a fascinating unknown to look at. Suffolk A98 crankshaft ends were a sad classic one here...clunk
...oh, left hand thread .
B&S engines can though continue well past book figure wear...I have run and operated quite satisfactorily B&S engines with non viably correctable wear...one being a 3.5hp on a Marquis which had "one final repair" by the local agent 15 years ago. It has wear on the exhaust valve guide that has to be seen to be believed.. but on it goes, slow reving and with a large additional flywheel helps I'm sure, but the valve still seals or it would not pump fuel up and draw it to start ok and run and does a days work every fortnight quite ok.."touchwood"
Perhaps you should arange a swop for that mighty 2 sroke rotavator that you saw on your holiday travels Terry.
I hope you can get the job beaten and back to good health.
All the best,
Clive.
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Guest
Hello John
My apologies for ignoring your question, I got carried away with valve seats. The answer to your enquiry is it depends on how far you intend to go. The machines were painted before assembly in the factory so when I have them stripped down for new seals I remove all cables and get everything except the engine and chaincase grit blasted. I also wire brush/disk sand the outside of the chaincase, keeping dust out of the bearings. I then use red oxide primer. Early (pre belt guard) machines were dark red. Later, circa 64-78 were mid red, not far off Hammerite smoothrite red. A brief period of light red was followed by orange circa 1980 to the end. The rotors, hitch and skid were silver grey. If your Merry Tiller has a front mounted fuel tank don’t use synthetic enamel on the chassis, carb or tank as if you leave the petrol tap on overnight the fuel will strip your nice new paint off.
Yes Clive the machine with all the grinding wheels is for the Valve + the rockers if applicable. You need another machine for the seats. The valve or seat could be cut to any angle so you set it to suit the valve.
Regards Richard
My apologies for ignoring your question, I got carried away with valve seats. The answer to your enquiry is it depends on how far you intend to go. The machines were painted before assembly in the factory so when I have them stripped down for new seals I remove all cables and get everything except the engine and chaincase grit blasted. I also wire brush/disk sand the outside of the chaincase, keeping dust out of the bearings. I then use red oxide primer. Early (pre belt guard) machines were dark red. Later, circa 64-78 were mid red, not far off Hammerite smoothrite red. A brief period of light red was followed by orange circa 1980 to the end. The rotors, hitch and skid were silver grey. If your Merry Tiller has a front mounted fuel tank don’t use synthetic enamel on the chassis, carb or tank as if you leave the petrol tap on overnight the fuel will strip your nice new paint off.
Yes Clive the machine with all the grinding wheels is for the Valve + the rockers if applicable. You need another machine for the seats. The valve or seat could be cut to any angle so you set it to suit the valve.
Regards Richard
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Cider Boys
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This subject takes me back a good few years, but from poor memory when rebuilding agricultural engines we used a valve seat cutter which you carefully placed in the valve seat and slowly rotated by hand with a light downward pressure, only taking off the minimum amount of seat to remove any pitting. The cutters were set to a particular angle 60,45 or 30, degrees. You then ground the valves in a machine like a bench grinder where you set the angle to say 1/2 to 1 degree less than you cut the face too. The machine was red in colour and you passed the valve back and forwards at the set angle. I never did this with horticultural engines, the smallest engines I rebuilt were usually Perkins P6 or Standard Ferguson type engines.
The theory was the valve would sit in the seat with an interence fit because of the slight angle difference. In pratice we still had to lap them in but this did not take very long. After lapping in the boss man would fill the heads with paraffin and see if any leaked by the next morning.
Barney
The theory was the valve would sit in the seat with an interence fit because of the slight angle difference. In pratice we still had to lap them in but this did not take very long. After lapping in the boss man would fill the heads with paraffin and see if any leaked by the next morning.
Barney
John,
I have to give Clive credit for this reply.
I had my first machine chasis shot blasted & then I primed it & top coated with Massey Fergason red. It is a close match to the original & a good self-smoothing paint.
I have to give Clive credit for this reply.
I had my first machine chasis shot blasted & then I primed it & top coated with Massey Fergason red. It is a close match to the original & a good self-smoothing paint.
I'll get the spelling right Clive!
I'll try to post a pic.of the valves seats conditions.
It appears that some metal object has been trapped between the seats of the inlet & exhaust valves at some time or that the t**t that owned it in some previous life tried to free the valves as they were stuck using a sharp pointed jobbie!!
A shame really as it's a 1982 engine and valve wear is minimal & the head/cylinder etc. is in good nick.
Hence the interest in restoring it.
The valve seats cannot be reground !
I'll try to post a pic.of the valves seats conditions.
It appears that some metal object has been trapped between the seats of the inlet & exhaust valves at some time or that the t**t that owned it in some previous life tried to free the valves as they were stuck using a sharp pointed jobbie!!
A shame really as it's a 1982 engine and valve wear is minimal & the head/cylinder etc. is in good nick.
Hence the interest in restoring it.
The valve seats cannot be reground !
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Clive.
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Hello Tel,
I see...it falls into the 3rd category then... damage inflicted in service/repair by something or somebody...It is always a terrible shame when gear that is otherwise ok gets muffed up like that....strangley fascinating but still annoying... but when progress is made and a way around it is found it makes it all the better to have beaten it..
Has it swallowed something..and given it a good chewing over.??...is everything in the carburettor in place.??
Have seen an instance were bits of spark plug have been dancing on a piston top....but valve seats are hard..and its not like they have piston coming to meet them....so wonder if it has been inflicted in a repair attempt in its past history.
I remembered today an interesting one with regard inflicted damage.
A Flymo GT4, with 4hp B&S vertical, needed looking at...the story was that it had previously had a crank fitted due to having a bent crank... it had been ok for a while but then got so it would only start and run for a minute then make like the Red Arrows and smoke just a little..!! Breather valve was suspected and it was changed for a known good s/h one... but still the same oil smoke.
Off with its head...to find a neatly machined slot with a round top in the bottom of the bore part way down... puzzling.??..so neatly machined. ..???
Further dismantling ensued...and a floating little end pin was found....minus its retaining clips.!!..evidently more previous work had gone on than a new crank...but someone had ommitted to fit a clip or two.!!
All the best,
Clive.
I see...it falls into the 3rd category then... damage inflicted in service/repair by something or somebody...It is always a terrible shame when gear that is otherwise ok gets muffed up like that....strangley fascinating but still annoying... but when progress is made and a way around it is found it makes it all the better to have beaten it..
Has it swallowed something..and given it a good chewing over.??...is everything in the carburettor in place.??
Have seen an instance were bits of spark plug have been dancing on a piston top....but valve seats are hard..and its not like they have piston coming to meet them....so wonder if it has been inflicted in a repair attempt in its past history.
I remembered today an interesting one with regard inflicted damage.
A Flymo GT4, with 4hp B&S vertical, needed looking at...the story was that it had previously had a crank fitted due to having a bent crank... it had been ok for a while but then got so it would only start and run for a minute then make like the Red Arrows and smoke just a little..!! Breather valve was suspected and it was changed for a known good s/h one... but still the same oil smoke.
Off with its head...to find a neatly machined slot with a round top in the bottom of the bore part way down... puzzling.??..so neatly machined.
..???
Further dismantling ensued...and a floating little end pin was found....minus its retaining clips.!!..evidently more previous work had gone on than a new crank...but someone had ommitted to fit a clip or two.!!
All the best,
Clive.
Thanks for all your replies folks.
Success! An old friend has found a cutter. A shaft was turned to suite the valve guides & the job's been done. The seats look good now so I'll lap in two new valves & rebuild. A primer & gold top cat should make it look very desirable. Bit like me after 6 pints.
Success! An old friend has found a cutter. A shaft was turned to suite the valve guides & the job's been done. The seats look good now so I'll lap in two new valves & rebuild. A primer & gold top cat should make it look very desirable. Bit like me after 6 pints.