Valve clearances

MikeT · Unread post by **MikeT** » 18 Sep 2008, 11:50

I just posted the measurements of mine in the Blog and wondered if I should re-shim them?

The exhausts are ok but the inlets are all over the place with two of them at opposite ends of the tolerance limit. My first thought was I mixed up the parts but I was very careful to seperate and identify them so I can't really understand what's wrong. Any ideas?

jgra1 · Unread post by **jgra1** » 18 Sep 2008, 11:57

hi Mike, did you do any valve work ?

Worth gettting then close if you can.. I have 8 shims lying about and Jim probably has another 100

but you'll need to take camshaft off and work out what you have and what you need.. micrometer and some simple spreadsheet calculations... etc.

John

edit

sorry Mike just read the blog

You did a fine paste lap of the valves..

anyway, i have some shims if it helps..

Unread post by **CitroJim** » 18 Sep 2008, 12:37

jgra1 wrote:hi Mike, did you do any valve work ?

I have 8 shims lying about and Jim probably has another 100

Yep, that'll be about right John

Mike, I have an Excel spreadsheet to take the hadache out of calculating the shims you need. It's up on my website but hidden. I'll advise the like when I'm home and can look at the server to see where it is..

You'll need a micrometer to measure them properly. You can get an adequate micrometer for less money than an adequate vernier caliper. You need to measure to two decimal places ideally. Also, measure clearances very accurately with a set of feelers that go down to .01mm otherwise your shim calculations will be wrong.

If you have a good imperial micrometer, that'll do, just convert the measurements into mm.

MikeT · Unread post by **MikeT** » 19 Sep 2008, 10:25

You're right Jim, I need a new set of feelers and my micrometer is imperial

I can't resume work until Sunday evening now but I'll pick up a new set of feelers while I'm out this weekend.

Shim sizes according to imperial micrometer.

1. 121-122 thou (3.07 - 3.1mm)
4. 120 (3.05)
5. 121 (3.07)
8. 118 (3.0)

Using mental guesstimations, I'm thinking of swapping 1 to 8, 4 to 5, 5 to 1 and 8 to 4.

Thanks for the offer of shims lads, hopefully I won't need them. By the way, I notice the shims are "wear marked" by the valve stem - would it make any difference flipping them over so the mark is mating the follower?

Unread post by **CitroJim** » 19 Sep 2008, 12:27

MikeT wrote: Using mental guesstimations, I'm thinking of swapping 1 to 8, 4 to 5, 5 to 1 and 8 to 4.

Thanks for the offer of shims lads, hopefully I won't need them. By the way, I notice the shims are "wear marked" by the valve stem - would it make any difference flipping them over so the mark is mating the follower?

That can often work wonders Mike!You may even find you can swap shims arround and find you don't need any replacements.

No, no worry at all about flipping them over. The wear will be so slight as to be inconsequential...

I've still not dug out the spreadsheet. I was a bit busy (non car) last night...

citronut · Unread post by **citronut** » 19 Sep 2008, 13:03

if you only did a fine paste lapping in you will probably get away with having to altter the clearances

regards malcolm

MikeT · Unread post by **MikeT** » 19 Sep 2008, 15:54

citrojim wrote:Also, measure clearances very accurately with a set of feelers that go down to .01mm otherwise your shim calculations will be wrong.

Easier said than found Jim! Any ideas where I could source a set?

Unread post by **CitroJim** » 19 Sep 2008, 16:37

Not in the usual places like Halfrauds Mike. You may well have to go to a pukka purveyor of quality tools. I had a set that went down that far but now it only goes to 0.02mm. The thinner feelers are mighty delicate and I broke the 0.01mm one years ago.

citronut · Unread post by **citronut** » 19 Sep 2008, 19:10

Mike have you not got a tool supplier to the enginering trade in your neck of the woods

regards malcolm

ps
stick this in a google search

engineer tool supplier Christchurch dorset

quite a few come up

MikeT · Unread post by **MikeT** » 24 Sep 2008, 15:08

I've tried various combinations of shims and followers and I've settled on the following measurements. It's not possible to get all lobes facing perfectly upright anyway so accurate measurement isn't wholly possible. I would prefer all the gaps to be under rather than over but what do you think, bearing in mind the BoL states the acceptable tolerance is +-0.08mm?

1. 0.18mm (+0.03)
2. 0.34mm (+0.04)
3. 0.33mm (+0.03)
4. 0.14mm (-0.01)
5. 0.14mm (-0.01)
6. 0.34mm (+0.04)
7. 0.34mm (+0.04)
8. 0.14mm (-0.01)

citronut · Unread post by **citronut** » 24 Sep 2008, 22:55

how tight are you doing the cam cap nuts up each time you fit the cam, in between mesuring the clearance's

as this will give you differnt readings each time

also it should be easy to get the cam lobes pointting upwards to mesure the gaps,
they do not need to be pointting upwardsto the exact micron

regards malcolm

Unread post by **CitroJim** » 25 Sep 2008, 07:53

Cam caps are tightened to a surprisingly low torque. 13 ft Lbs if my memory is right. One set of nuts I always use my low-range torque wrench on.

Those clearances look OK to me Mike... Again from memory...

MikeT · Unread post by **MikeT** » 25 Sep 2008, 10:32

I torqued the nuts to 20 newtons as per BoL, Malcolm. All I know is that if I stop the lobe before or after (TDC shall we say

) I will snag the feeler that previously slid in snugly. I'm assuming the difference is 0.01mm or less but it's perfectly repeatable. After taking several sets of measurements (without removing/refitting the caps) I'm satisfied they're well within tolerances.

Next job turbo and manifold...

MikeT · Unread post by **MikeT** » 04 Oct 2008, 11:25

If anyone else is looking for a decent set of feelers I can highly recommend http://www.virtualvillage.ie/ (search for "feeler") for the princely sum of £3 inc p&p from China. Much cheaper than rip-off Britain's £10-£15+£4 p&p I found.

They even come in their own plastic case and a 25% off next purchase coupon.