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MG MGB Technical - Tappets

On my 1975 gt the tappets seem very noisy. I have adjusted to 15thou cold and even used a tool which is supposed to take account of wear but still very noticeable noise. Is this normal?


Rod
Rod Merrall

Yes, this engine is known to be noisy (especially compared to modern cars), which is why some fit an alloy cover in an (only partially successful) attempt to quieten them down.

Did you check the gaps after using the tool (QuikAdjust?) you mention?

Where are you positioning the engine to adjust them? One thing I and a few others have found is that the biggest gap isn't always at the strict 'rule of nine' point which is usually the position quoted. Although in theory the back of the lob should give the same, maximum clearance anywhere between shortly after the valve having close to shortly before it starts to open that isn't always the case. Several of mine vary considerably round the back of the lobe, and locating the point of biggest gap on each one and adjusting there did make a noticeable difference. Quite long-winded though even with a dial-gauge.

paulh4

Tappet noise tends to be more noticeable at certain times - when you have less to concentrate on as a driver. Once you and the engine have warmed up and driving the car out of town and/or Sunday bimble mode you'll notice less.

The oil you use and how warm the oil/engine is can make a difference.

Alloy cover, bonnet insulation and general car insulation, soundproofing, sound deadening, lush carpeting will make a difference to how much you hear.

If you've got an ally cover with bling chrome oil filler cap those aren't as good for engine breathing as the standard plastic vented and filter oil filler caps. You could spend ages checking and trying to get the perfect 0.015" gap on each tappet and as soon as you drive the car it could be no longer perfect.

Some don't find those click tools to be effective (or even the right idea but the reason is beyond limited understandings).

I bet if you check the settings after your next run you could find more adjustment and probably every time. As long as they're reasonably right that's usually enough.

Of course if you've adjusted the tappets you'll also need to check, and adjust as required, points, plugs, timing and mixture in that order.



Nigel Atkins

"I bet if you check the settings after your next run you could find more adjustment and probably every time."

That's caused by the changing gap round the back of the cam as I described. It can make repeatable measurements impossible even just turning the engine one revolution never mind running it. Since adjusting mine at the point of biggest gap they've not needed further adjustment from one year to the next.

Why mine - and others, is like that I have no idea short of taking out the cam and checking it, but as the engine runs really well I'm certainly not going to do that.

"if you've adjusted the tappets you'll also need to check, and adjust as required, points, plugs, timing and mixture"

Can't agree with 'need'. If you are doing a full check-up then yes, but simply adjusting the tappets isn't going to change any of the others by itself.
paulh4

Depends on how much adjustment was made on the tappets and if all former tappets gaps were even or thick and thin adjustments, might affect the timing/running.

If just checking then or very minor running adjustments then perhaps 'best' rather than 'need', I think I used to put 'best' but at some point changed to 'need'.

You do a second run to check your gapping so you could do the rocking or double system.

I'm very happy to drive up to the second city and allow you to prove your method on my car if it's not as above, I'm always happy to watch someone else doing the work on my car rather than me. I'm very poor at gapping the tappets and plugs, they're such crude methods of holding a screwdriver against a spanner and spark gapping tool (that never seems to to fit the electrode well) that require skill I don't possess.

I check the tappets less regularly now and only adjust them if they're out by too much.
Nigel Atkins

Adjusting tappets can make minor adjustments to valve timing, but not ignition timing.
Dave O'Neill 2

Has anyone ever tried adjusting the tappets with the engine idling slowly. This used to be the preferred method on GM and Vauxhall engines. I find it works very well on the MGB just adjust until the feeler gauge is a light drag through. This method has the additional advantage that the noisy tappet will be silenced immediately you insert the feeler allowing you to give it additional attention

Good luck
Iain MacKintosh

There is one sure way to reduce noise - not for free but PTFE cuts noise on all I.C.E but is really effective in quietening push-rod engines.
Roger Walker

Ian, Be prepared to sacrifice some feelers it the rocker faces are a bit undercut. But it does work well if the faces are decent, and it allows for that "not quite the back of the cam" issue noted by Paul.
As for the Aluminium rocker cover I never thought it did much quieting. But I have seen B's with a "Tea cosy" on the cover!!!
Allan Reeling

Apologises Dave I should have put running not timing.
Nigel Atkins

Am I also thinking of this back of the lobe thing wrong too with your moving the engine back and forth looking for the widest gap?

My understanding too was that a a thou or two out at the tappets wasn't a big deal?

Nigel Atkins

Since the setting is 14 to 16 thou then no a thou or two isn't a big deal. But if the differences round the back of the lobes range wider than that? Then it becomes significant. If they are only a thou or two different after one turn of the valve gear then you might ignore it. But when using feeler gauges of 14 thou as a go and 16 as a no go I certainly wasn't happy finding that 14 would slip one time then it wouldn't, or conversely 16 wouldn't fit then it would. Unless you then measure exactly what the gap is, how do you know the difference IS only one or two thou and not something significantly more? I went further as I don't like question marks and unexplained inconsistencies and checking the clearances throughout the whole of the backs of the lobes I found the variations much more than that, with the point of widest gap being anywhere from just after the valve has fully closed to just before it starts opening, and different for every valve. I only found one out of the eight where not only was the gap the widest at the rule of nine point, but that it wasn't changing as it passed through it. And as I said before once I adjusted at the widest gap they were definitely quieter.
paulh4

I actually like your system, spend more time up front to save time latter and know you've set it right. No good for me as I don't have the patience with working on my car or the skill to quickly set the gap correctly but good for those that do.

Means you can have the needle in the orange segment more often with an easy mind. :)

I've found you often need to push on the rockers to ensure the gap is actually at its widest and a set of stubby feeler gauges, would make the job easier but I couldn't find any in imperial when I was looking.

Perhaps like many things on these cars the lobs vary between individual cars a lot more than might be expected and some work better than others using the rule of nine that not everyone uses or accepts as best (I think FRM would have used a different method).


Nigel Atkins

Needle in the orange? Gawd no, way too much noise, I probably don't even reach 5k. I'd rather change down and use the torque. V8 by comparison revs into the red all too easily and needs watching.
paulh4

I normally don't go into the orange(?) section and with V8s I'd often forget to change down when I was just bimbling or enjoying the burble. Never had trouble adjusting the tappets though.
Nigel Atkins

Beats me why people fit adjustable push-rods to the Buick/Rover V8 when it has hydraulic tappets.
paulh4

I guess it'd be to do with racing or vanity/ego perhaps on a road car(?), Willy would probably know.

You can probably guess which type I had in my engines (and all without CB points of course).
Nigel Atkins

Beats me why people fit adjustable push-rods to the Buick/Rover V8 when it has hydraulic tappets.

Using adjustable push rods allows you to set the tappet pre-load, without introducing rocker post shims. Particularly good when the heads and deck have been skinned and multiple shims would be needed. Shims change the rocker, valve stem interface angle.
Allan Reeling

I found confusing information on the RPI web site about this. Fitting new cam and tappets years ago a figure of 20-60 thou had been bandied about and was quoted on the RPI site. I was a bit taken aback to find mine were 110-120 on the right and 40-110 on the left. Spoke to Clive Wheatley and the MGOC and their opinion was that unless the engine is highly modified there shouldn't be a problem as the whole purpose of hydraulic tappets is to cope with a wide tolerance in the rest of the valve gear. Spoke to someone at RPI, who despite what was written on their site said "you wouldn't want to go as low as 20 thou and 120 thou should be fine".

Neither could I understand 'pre-load', surely you need a clearance when dry that oil in the tappets takes up?

How is shims changing the rocker and valve stem angle significant? Surely that is changing massively all the while the engine is running?
paulh4

Skimming the block and/or head will effectively lengthen the pushrod, thereby altering the rocker geometry.

Shortening the pushrod will restore the correct geometry.
Dave O'Neill 2

Rod-
If your valvetrain seems to be excessively noisy even though the condition of the rocker shaft and rocker arm bushings are good, then be aware that this condition may be caused by a bent pushrod. In order to examine for this, start the engine, and then watch the valvetrain in order to determine if one of the rocker arms is reciprocating against the coil spacer spring on the rocker shaft, and then returning to its original position against the rocker shaft pedestal, thus producing a loud tapping noise as it contacts the rocker shaft pedestal. In some cases this oscillating movement is too small to be readily discerned by the eye, so it becomes necessary to insert a blade-type feeler gauge between each of the rocker arms and the rocker shaft pedestals in order to feel for this impact. This oscillating movement of the rocker arm is produced by a bent pushrod.
Stephen Strange

(Allan, I hope you noticed my question mark. :) )

A mate bought an engine off RPI and he wasn't overjoyed with it or them or their attitude or service, now I know even the best can make mistakes but I also know from much experience that some companies and people get and maintain a high and good reputation above, and opposite, to what they actually deserve, this may or may not be the case with RPI.

Clive Wheatley I can't remember ever dealing with but David Vale was always very helpful and kept excellent records of the conversions he supplied to. Looks like he's still going, part time.
Nigel Atkins

Ha ha ha ha, Nigel, that's really funny,ha ha ha
You'd remember if you'd rung Clive, you'd probably still be on the phone - doesn't mind a chat
I don't really want to get into a camshaft / rocker geometry school here but Dave is correct in what he mentioned
Paul's out of whack clearances are typical of Rover v8's, there's always a difference from one side to the other for some inacurately machined reason.
That's where, for the average std roadcar the hydraulics can suck that up but for it to be 'right' the rocker geometry needs measuring up and the pedastals shimmed or machined off to correct that then pushrod length determined and suitable length pushrods fitted ,either set length or adjustable
If still using hydraulics usually there ends up being one length for one side and another for the other, just because
If it's got solid lifters then adjustable pushrods are the easy go, 'but' the rocker geometry has to be correct first- any change of camshaft or valve length will require rechecking geometry and head or block machining will need pushrod checking/adjustment
If running variable duration hydraulic lifters you'll soon find out how sensitive valve clearance / pushrod length is, it's a real eye opener but very rewarding when you hit the magic spot
Paul , the difference between clearance and preload methods is-
You have done yours by collapsing the lifter right in and measuring the clearance .120" with the plunger at the bottom of it's travel---all good
The other method is to simply measure how far the plunger is collapsed from it's fully extended position-ie-out against the circlip, that's where the 20-60 thou 'preload' is measured as in 20-60 plunger depression from 0
This is an easy method if the lifters are full of oil as you don't have to squish them down and can be done by screwing the rocker gear down till the rocker just takes up the slack and from that point it should be 'roughly' one turn on the pedestal bolt till the pedestal seats on the head giving the 20-60 preload on the lifter--clear as mud

As far as having to wriggle around finding a spot on the back of the lobe on a 4cyl MGB camshaft to set the clearances goes---it should be in the bin if it's that far out, what's the rest of it like ,phasing,lobe shape,lift etc---throw it out
I showed this thread and riggling round clearance setting method to my camshaft mate and she just shook her head and walked away muttering ,'you're joking'

willy
William Revit

Make sure that the rocker shaft is tightly secured. I noticed an excessive tapping sound in my 1970 and found that the rectangular head screw that secures the rocker shaft to the tower had not been properly tightened before it was locked in place. A half turn quieted it down and kept the rocker shaft from rocking back and forth against the screw.
Glenn Mallory

Contrary to popular belief, the B cam profile is not inherently noisy. I have analysed many cam profiles in detail at some length over the years, and have found that most of the BMC profiles have the same characteristics leading to and around the take-up point regardless of whether it is A or B series, a race cam or a road cam. Quite apart from manufacturers' tendency to not waste money reinventing the wheel where not necessary, this is not surprising because the two engines share the same cam follower diameter, which is one of the key restraining parameters on profile design.

A new MGB camshaft accurately ground does in fact run quietly. Things that makes it noisey include:
Poor manufacture - base circle run-out as described by Paul and commented further by Willy. I found this to be an issue even in genuine camshafts when they were still available.
Cam follower wear, which alters the shape of its working face from slightly convex to flat and eventually concave if left long enough. This in turn results in different clearance take-up dynamics, in which the lobe smacks broadside on to the follower's foot rather than the controlled motion which the correct shape provides.
And of course excessive clearance makes for noise.

The initial part of the B cam motion is a steady speed with a lift rate of about 3 thou per 10 degrees (at the lobe). This constant lift velocity extends to about 11 thou lift off the base circle, (which translates to 15-16 thou at the valve) and allows the clearance to be taken up gently (and therefore quietly).
Immediately after this take-up period the valve train velocity accelerates hard to reach a maximum of a bit over 30 thou per 10 degrees within the space of 20-30 deg of crank rotation.
Once the clearance is such that the take-up gets into this hard acceleration phase, then the take-up velocity is much higher than intended ... which we hear as noisey tappets. And no prizes for guessing that higher take-up speeds result in higher wear rates.

From this it is easily seen how having significant base circle run-out shifts the take-up point (and velocity) to something that wasn't intended.

What is interesting is that in the B series BMC specified the clearance to be at the end of this take-up period. Hence any wear in the valve train that increases clearance is going to plunge it straight into the zone of hard acceleration and the associated greater wear rate. So between tappet-checking intervals it is inevitable that the engine will have been running in this zone for at least part of the time.
On the other hand, the A series clearance for the same take-up profile is specified as 12 thou (which after allowing for rocker ratio difference) is 2 thou less than the B series. This allows room for a wear-and-reset cycle without getting into the high wear-rate zone.
So I have always set tappets to the A-series point, which has made for extended valve gear life. And quieter operation because it stays within the intended take-up velocity range.

If a correctly set tappet clearance is noisy, is is almost certainly an indicator to worn cam followers. (Here I stress correctly set, and acknowledge that wear on rocker tips and bushes can make this a challenge to achieve.) Worn followers in turn start pitting, and the pitted surface is very agressive to the cam lobe itself. We have seen lobes worn to as little as 1mm lift.

Camshafts are much harder and more expensive to replace than followers (unless you own a 1275 A series) so it always pays to investigate follower soorner rather than later when tappets are noisey and renew them if showing the slightest sign of pitting. That way you can save tha pain of unnecessary camshaft replacement.



Paul Walbran

This 'funny' cam is on a car I've had for over 30 years and has always been the same. Years ago I did take all the followers out to check them and the cam for wear, and the camshaft bearings for wear by seeing if I could move the shaft laterally or up and down, and nothing. Like I said it's always run very well - and quieter now - so I'm not going to do anything else until it needs it.
paulh4

Does anybody know what the B series cam profile drawing number is or better still have the drawing. The profile number will be referenced on camshaft drawing. It probably starts with 8A****
The A and B series profiles are Jack Bishop's patented Multi-Sine wave designs which were world leading at the time.
Paul Walbran is correct the control on base circle run out in North works Longbridge wasn't the best as the shafts were ground on centres.
I have renewed everything in my B valvetrain and its still noisy. I've taken to setting the tappets tight on the 15 thou feeler. I cant see much harm in setting the inlets at 13 thou. I believe my new standard camshaft came from India. It's steel and I would say its induction hardened rather that nitrided.
Paul Hollingworth

Just guessing,, a lot of the ADO numbers transfered over into part numbers so would/could it have been -
48G184 or 88G252 or something like that
William Revit

Paul-
What do you mean by "the A-Series point" when you say "I have always set tappets to the A-Series point"?
Stephen Strange

How noisey, or very noisey, the tappet noise (whatever the actual source) can be very subjective even with side-by-side comparisons of running engines.

I got my mate to set the tappets recently and I noticed the tappet noise more which I jokingly told my mate and his reply "turn the radio up". As if it's worth the effort of having a radio in a midget!

If when driving I could hear the tappets over the road noise, exhaust, induction, g/box and rear axle whines I'd be worried. My car doesn't have any soundproofing material, but sound deadening pads and the cheapest thinnest carpeting known to man, so I get plenty of noises.
Nigel Atkins

Steve
I'm pretty sure Paul means the same touch point up the quietening ramp of the cam
With the A series set at .012" the follower contacts before the end of the ramp whereas the B series set at .015" has the follower contacting the ramp right at the end just before the lift rate changes
Setting a B series at around .0135" gives the same result as the A series at .012"

Having experimented with this, I've run a B up the road and got it stinky hot , pulled the cover off and set No1 clearances to .0135" red hot with a dial indicator,then left it to cool right down--Rechecking them 2 valves dead cold without touching anything gave cold clearances of .013"In and .0148"Ex , so that's what I set std. MGB valve clearances to now , cold with a dial indicator

Probably shouldn't be answering for Paul but I just like talking cams
Sorry Paul,
willy
William Revit

The B series is before my time but I have seen the profile drawing and the design calculations. For some reason the number 8A1686 sticks in my mind. I doubt very much that the clearance takes you right to the top of the opening and closing ramps but there might not be much to spare. That's why it would be good to get hold of the original profile drawing. It could be that Jack didn't intend for the clearance to be 15 thou but that's what the development engineers settled on.
I was involved in redesigning the A series cams right at the end of its production. I think it coincided with the fitting of twin injectors. The idea was to make the engine less sensitive to badly set tappets by extending the ramps. Mini buyers were taking them back to the dealers before the normal 1st service. We also managed to maintain the 72hp output.
Paul Hollingworth

Willy, you are welcome, indeed thanks, as I have to spend a sunny holiday weekend building a race engine ....
And spot on. You obviously got it stinking hotter than I did on a similar comparison as I got only 1 thou variation.

Paul - very intersting on the injected A-series. I got the quietening ramp ending at 15 thou from campro analysis.

While all this talk of ramps etc gets nutters like me excited, the main points are these:
1. Tappets shouldn't be noisey if they are set correctly and the valve gear is in good order.
2. Excessive clearances are hard on followers, so never live with noisey tappets.
3. Most times excessive noise remaining after the tappets are set correctly arises from worn cam followers.
4. Worn followers will eventually wear out the cam lobes, so take correctly set noisey tappets as a warning to check and if necessary renew the followers. It's easy to do, and much simpler and cheaper than replacing the camshaft.
Paul Walbran

The only chance any of the old records exist from Longbridge is that individuals took them home. Lets hope so.
In cam profile design there is always an argument on how the period is defined. In my time we defined the period between the ends of the constant velocity ramps ie the part of the profile where the follower is accelerating. Others define it as being above a certain nominal lift of base circle typically 1mm. Having studied the A series cams I couldn't make any definition tie up with the quoted periods. I think that old Jack cheated. Development engineers always want the maximum lift on a relatively short period for idle stability, emissions and drivability. Any fool can design long period cams.
Paul Hollingworth

A huge amount of stuff from Longbridge became the starting point for the Gaydon museum.
paulh4

Most paper records were kept at Longbridge until 2005 when MG Rover collapsed. I do wonder what happened to the microfiche copies of the drawings, only of use if you know the part numbers of course. Fords ownership of the Gaydon museum was a deterrent to sending stuff there. I think its owned by TATA now. When SAIC shut the Longbridge technical centre I don't think what was left of the remaining records found their way to Gaydon. Its seems to me that the new MGCC archive at Kimber house maybe a safer refuge if anything can be salvaged.
Paul Hollingworth

Ford only owned the premises from when BMW sold Rover. The collection - vehicles and documentation - is the property of BMIHT held first at Studley from the late 70s then at Gaydon from the 90s. While Gaydon was being built I saw some of the vehicles at Studley with the chap who was the prime-mover in setting up the trust and Gaydon for which he was awarded the MBE. There had been a small fire in a basement at Longbridge and he was one of the people who went in to clear it up, and realised just what a valuable historical resource it all was. That's the era of Longbridge I was referring to.
paulh4

BMC specified a timing clearance at which the specified opening and closing events occur. Accounting for the rocker ratio this appears to be at 16 thou of cam lift off the base circle, at which point it is well into the acceleration phase. It always seemed to me this was done to use a point that is less vague, easier to measure and better represents when the valve starts moving significantly rather than gradually. If the lift is plotted graphically this point is close to the apex of the tight curve at its foot.

50 thou off base circle is another common reference point, as at that stage velocity is high and provides much better resolution between profiles.

Similarly, lift at TDC (at which point the velocity is high for any worthwhile cam profile) provides a means of checking timing with excellent resolution.
Paul Walbran

The 16 thou thing has always amused me, It makes it into a project to compare BMC grinds to aftermarket grinds
Most aftermarket cams available here are supplied with .050" lobe lift specs for setting up but are spec'd at advertised duration as well which is measured at .003" valve lift off the seat--usually
It would be really nice if everyone spec'd their stuff the same way
Bit like oil filters, why are their 17,000,000 different filters-should be 3 just like the three bears--little-middle-big
Having 100% faith in my camgrinder of choice, I can set up on the lift at TDC method spec'd on the card and be happy that it's spot on-every time and it's also a simple method of measuring if moving the cam timing around as well, just one measurement and it's done
I like simple-
willy
William Revit

Firstly, I would say to Paulh that all the drawings and design calculations for the powertrain were held at Longbridge. This covered anything from about 1960 onwards. All Rowertrain and Chassis activity for BMC was centred at Longbridge. The stuff from Canley was brought over in about 1980. That may have been cleared out and sent to Gaydon in the late nineties.
Having studied Jack Bishop's A series drawings in great detail I can assure Paul Walbran there was no such thing as a 16thou rule for the timing period. The Multi-Sine Wave mathematics defined the lift for when the follower was accelerating/decelerating. The opening and closing ramps were added afterwards manually ie the ramp height was added to all the lift ordinates. Similarly the ramp velocities would have been added to the eccentricity numbers.
When we were doing the re-design of two profiles in the late nineties we found on the shortest of them that the timing point was at almost the peak acceleration point of the flank. So a definite cheat. The replacement profiles we designed performed almost the same as the originals requiring only minor tweaks to the calibration. There's only one way to settle this and that is to get hold of the profile drawings. First step would be to know what the profile numbers were. They will be referenced on the camshaft drawing. It may be possible to find them using the quoted lift and period.
If you want to know more about the Multi-Sine Wave method you need to read Jack Bishops IMechE paper from the late sixties.
Paul Hollingworth

Paul Holl---

"I can assure Paul Walbran there was no such thing as a 16thou rule for the timing period."

-.016" lift at the lobe has been the checking spec for BMC camshafts since Adam was a boy . It's always amused me why .016" why not some nice round figure like 15 or 20 or 30, but no, it's 16
At least most cam grinders now all use the same .050" figures so comparing basic cam grinds with others isn't such a task

William Revit

Hi Willi,
There was something quirky about how old Jack defined his profiles. He called the back of the cam the clearance circle not base circle. He defined the base circle as an imaginary circle that went through the timing point. The lift ordinates were positive above the base circle and the ramps were shown as negative lift. The people who set up the cam grinders would have to have corrected this by adding the ramp height to all the ordinates. This also means that the lift above the clearance circle was greater than the quoted lift. When we did the A series re-design we considered two profiles one for a 64hp spec, and another for a 72hp spec. I don't recall the ramp heights being the same on the two profiles and 16 thou doesn't ring a bell at all. It was clear from the drawing that Jack had included some of the flank (the bit were the follower accelerate) of the cam in the ramp table. We always showed the eccentricity (the distance of the point of contact on the follower from the centre line) in a table on the drawings too. Eccentricity relates directly to velocity by the constant 180/PI. Seeing these numbers increasing told you straight away that the follower was accelerating. If we knew the profile numbers, I might be able to get hold of a drawing. Does Visard list them or just the camshaft numbers ?
Its annoying that I can remember so little without access to the files. 16 thou at the cam would be 20 thou at the valve so setting at 15 though you would still be on the ramp but we know its not constant velocity towards the end.
Paul Hollingworth

Hi Paul
Yeah, both the MGA w/shop book and the MGB special tuning book quote .021 for cam timing checking clearance so yeah ,you're on the money there
Not sure what Visard says, he does say a lot-!
For me, David Anton would be the man , I'll ask
No promises but --
William Revit

btw
I can see the logic behind Jack's base circle /clearance circle specs but yeah the cam grinders would have to know where he was coming from
I've been Americanised for years, it's a lot simpler---base circle round the back then everything goes up from there
Just from what you've said he reminds me of Colin Chapman---we'll do it this way , they're all wrong
Hopefully we can get hold of the profile ,we'll see
cheers
William Revit

We continued to call the back of the cam the clearance circle right up to the end at Longbridge but we showed all the lift values as positive. We defined the period as being between the ends of the constant velocity ramps.(so the part of the cam where the follower was accelerating)
A and B series, initially at least, camgrinders in North works would have been controlled by a Master Cam. This was a large cam about 1 foot in diameter made by a tool maker. I cant say I've ever seen cams made like this, in my day it was all Computer Numerically Controlled. We just sent the the computer file so we could get a camshaft with a different profile made the same day.
I've dredged up some drawing numbers off the net, 2A297 and 2A571 which are said to be 0.221" lift by 230 deg period. They wont be of course for the reasons explained above. The numbers do seem likely candidates but they could be camshaft numbers rather than Cam profiles. Other possibilities quoted are 8G712, 88G229 (different lifts and periods). The B series is shown as 88G303.
Cam designers around the world use a textbook by MC Turkish (of the Eaton corporation) as reference so we are all Americanised to some extent. Jack had long debates with the American Winston Dudley the inventor of the Polynomial method about who's method was best. Some of the correspondence is shown in Jacks IMechE paper.
Paul Hollingworth

Its interesting what comes up if you Google J L H Bishop.
Paul Hollingworth

If you Google J L H Bishop you can get his paper from 1951 and all the correspondence. Look for a link to Citeseer. The form of Multi-Sine Wave shown in the paper is an earlier incarnation than the one I used. Jack added another sine wave to improve the shape of the acceleration diagram (or as he called it the instantaneous radius of action) He gave a lecture at Imperial collage in the late sixties where he went public. Unfortunately I don't have a copy of his notes any longer. I'm not sure which of the A and B series cams use which version.
What a clever man he was. He had no degree just a Higher National Certificate.
Paul Hollingworth

Just got back to this after a hectic week. Paul, thanks for such very interesting posts.
Paul Walbran

This thread was discussed between 20/10/2020 and 05/11/2020

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