a bit confused about tappet clearances

Hi all,
I'm currently getting a Lister D that was given to me up and running. i've come to the part where i need to set the valve/tappet clearance. As i began to look into this i noticed that .31thou was a common number. But i then read a post on a forum that stated that .31thou was a misprint and that running a Lister D at .10thou works perfectly well.
probably the reason why i'm a so confused is because i'm 15 and i've used centimetres and millimetres all my life and i have know idea wether .10thou is smaller than.31thou or not:oops:  
and just to be certain .31thou is exactly the same as 0.31thou or is it 0.031 thou:?:   
Thanks for any help given, I'm so confused about imperial measurements   
Callum

callum12 wrote:Hi all,
I'm currently getting a Lister D that was given to me up and running. i've come to the part where i need to set the valve/tappet clearance. As i began to look into this i noticed that .31thou was a common number. But i then read a post on a forum that stated that .31thou was a misprint and that running a Lister D at .10thou works perfectly well.
probably the reason why i'm a so confused is because i'm 15 and i've used centimetres and millimetres all my life and i have know idea wether .10thou is smaller than.31thou or not:oops:  
and just to be certain .31thou is exactly the same as 0.31thou or is it 0.031 thou:?:   
Thanks for any help given, I'm so confused about imperial measurements   
Callum

thou means thousands of a inch so 1 thou is 0.001

whats your email i can email you a manual , matt

Hi Matt,
being a new member i can't post emails or links for 7 days.
so, what i've done is i've put my email into my profile under Jobs/Hobbies. so you should find it there.
thanks for the help,
Callum

Hi Callum,
this why when I measure anything around my 4 year old I show him metric and imperial

its not .31 thou that would equate to 0.00031" ie less than a thou.

The measurement in the manual is 0.031" which is 31 Thou or thousandths of an inch.
Don't get too hung up on it for now, its decimalisation of inches but all you need to know is the number .031" and have access to an imperial feeler guage. .010" or 10 thou is a smaler gap but I would be inclined to go with the manual.

Where (roughly) are you, if your parents were happy about it somebody may be local and able to help you a little.

If you fancy a laugh ask a teacher to explain thou Most these days will not have a clue what you are talking about

Callum,
I did my time in the metric age as well and still find imperial a bit of a pain.
Best way to deal with it is to remember just one thing, that there is 40 thou to a mm. So , if your manual says 30 thou then its 0.75mm. I have done most of my work on metric lathes and am in the habit of doing the conversion in my head every time I make imperial parts. The drawings may be imperial but I still think metric.

With valve clearances I would not be too worried about loose clearances. When I raced motorbikes we always set the clearances at the outer limit, The thinking was that a loose clearance will just make the engine a bit noisy, tight clearance and you run the risk of burning valves. For these old engines I don't think its too important. You could run 0.030" ( 0.75mm ) all day long and it won't hurt a thing.

Peter

Thanks everyone,
my granddad used to be an engineer so i'll have chat to him about. although now i know how to go about setting the clearance i should be good.
just to make sure, with feeler gauges if you don't have the right size you can use multiple to get the required size? i would assume so.
thanks again,
callum:D 

Callum, I stated my apprenticeship with BR in 1970 and was right on the transition between imperial and metric. I still have a bad habit of measuring things using both... and using the measurement that is easiest to read on a rule or tape. As for multiples of feeler gauges, no problem - just make sure they are clean with no dirt in between the 2 (or 3) and all should be good. It was drummed into me that when used, feelers should be a smooth sliding fit and not a tight in the gap being measured.

pjjms, what bikes did you race? I raced grasstrack and speedway for many years and used 500cc Weslake engines before going onto sidecars with Honda Fireblade engines. I always used max clearances as well. My engines often sounded rattly, but went well and often surprised a fellow competitor who thought the sound meant a bad engine. I did drop a valve (or 3) once in the Honda at 16000 odd rpm ..... carnage ensued - ££££many!


Steve

I was into road racing Steve. Finished up on an F1 bike built up from the last of the CB900's along the lines of the US superbikes of the time (that's a few years ago now). Took it out to 1062cc, and it went great. I liked endurance racing and had the advantage of being able to build reliable engines. I was always amazed how many bikes could not last a 2 hour race. Got some podium finishes for just that reason, sure wasn't my riding as there were guys riding faster. I still build bike engines for a few guys.

Sorry Callum, hijacking your thread a little here.

For a Lister D 10 thou clearance is fine.  A Lister engineer told me that they just made sure there was a gap and left it at that, they are not exactly high speed engines so the gap wont change much when running.

Pete.

thanks for that every one, i'll set it to 31thou and see how that goes. 

callum12 wrote:thanks for that every one, i'll set it to 31thou and see how that goes. 

TEN THOU WILL BE FINE!!!!! 

Pete.

Well i would leave it if it was at ten thou but since the head has been off ect i will need to set them so i might as well set it to what its supposed be. unless it will run better at ten thou? if 31thou doesn't do it i will try ten thou.
thanks

callum12 wrote:Well i would leave it if it was at ten thou but since the head has been off ect i will need to set them so i might as well set it to what its supposed be. unless it will run better at ten thou? if 31thou doesn't do it i will try ten thou.
thanks

just set it to ten thou and be done with it !

matt

callum12 wrote:Well i would leave it if it was at ten thou but since the head has been off ect i will need to set them so i might as well set it to what its supposed be. unless it will run better at ten thou? if 31thou doesn't do it i will try ten thou.
thanks

Callum. 31 thou was a misprint, David Edgington admitted that in his book and has now (in the reprinted book) corrected it to 10 thou as Listers advised.  I have four D types and they are all set to ten thousands of an inch.

Pete.

[quote="callum12"]thanks for that every one, i'll set it to 31thou and see how that goes. 
[/quote]
Good plan, set them at 31 thou, or more then you can sit there and sleep to the sound of the rattly tappets.

Villiers wrote:

callum12 wrote:thanks for that every one, i'll set it to 31thou and see how that goes. 

Good plan, set them at 31 thou, or more then you can sit there and sleep to the sound of the rattly tappets.

   

sorry i sent it twice so i deleted this one
 

I assume Villers was being sarcastic when he said "Good plan, set them at 31 thou, or more then you can sit there and sleep to the sound of the rattly tappets."
I wasn't doubting any of your knowledge or being stubborn, i just wanted a simple yes or no answer as to valve clearances.
I will be setting it to 10thou as you've all made it QUITE clear that it should be 10thou.