Doing my valve clearances - Updated!

[monkeywithaplan]

Right, shims back in, all valves re-measured, this is what I got, not nearly as bad as it was before, lol!!



So I got one exit valve that is pretty bad, 2 inlets pretty bad and 2 inlets just outside the range.

What would you do?

just outta interest, do yo hav the original sheet that has the details of when you measured the clearance between the rocker arm and cam? interested to see how off this makes the measurements.

cheers
david

[viper_biker]

just outta interest, do yo hav the original sheet that has the details of when you measured the clearance between the rocker arm and cam? interested to see how off this makes the measurements.

cheers
david

Dave, it shouldn't have any sort of corellation between the two. The gap between the cam lobe and top of the rocker arm and the gap etween the bottom of the rocker arm and the shim have too many variables to have any sort of formula.

[oliherst]

just outta interest, do yo hav the original sheet that has the details of when you measured the clearance between the rocker arm and cam? interested to see how off this makes the measurements.

cheers
david

Dave, it shouldn't have any sort of corellation between the two. The gap between the cam lobe and top of the rocker arm and the gap etween the bottom of the rocker arm and the shim have too many variables to have any sort of formula.

Dave, yes I do, but as Viper says there is no corellation between them, if you are interested I can post them up after work? Some clearances were exactly the same, but most were totally different.

Would it possible for someone to help me identify the shims I can swap and those that I need to replace? I'm currently working it out for myself as much as I can, but help from someone that has done it before would rock! :)

[oliherst]

I'm not sure if it would be best to just get them all into tolerance, or if I should try and make them all the same and aim for the middle range?

To just get them into tolerance, is this correct?

Cylinder 4 exit - swap 2.28 for 2.25, new clearance = 0.21
Cylinder 4 inlet - swap 2.30 for 2.25, new clearance = 0.12
Cylinder 4 inlet - swap 2.36 for 2.30, new clearance = 0.14
Cylinder 1 inlet - swap 2.30 for 2.25, new clearance = 0.16

Now if I do that I can get them all within tolerance, but is that best practice, should I be trying to make them all the same? Or getting them all in the middle of the tolerances? or both?

[CMSMJ1]

It depends on how you want it mate. Getting them in tolerance is a good start and will suffice - this is why Honda gave us a broad range of allowable clearances.

There are benefits from having slightly loose clearances in terms of a guaranteed seal but then you get slightly more valve opening if the clearance is tighter... but not too tight as then you get poor sealing..

The HRC manuals have clearances listed as .015 +/- .02 and 0.20+/- 0.2

So I would for for slightly tighter exhausts and middle of the range inlets if I had the shims to do it.

[oliherst]

Well I have spoken to the lovely Rick O this morning and he will do swaps for shims he has in stock at a great price and can get them from Honda cheaper than my local Honda dealer can (go figure ) if he has to order them in, so I'm not adverse to swapping out every shim to do the job properley once rather than badly twice :D

I guess I need to get the measurements for the rest of the shims next then.

[monkeywithaplan]

just outta interest, do yo hav the original sheet that has the details of when you measured the clearance between the rocker arm and cam? interested to see how off this makes the measurements.

cheers
david

Dave, it shouldn't have any sort of corellation between the two. The gap between the cam lobe and top of the rocker arm and the gap etween the bottom of the rocker arm and the shim have too many variables to have any sort of formula.

Dave, yes I do, but as Viper says there is no corellation between them, if you are interested I can post them up after work? Some clearances were exactly the same, but most were totally different.

Would it possible for someone to help me identify the shims I can swap and those that I need to replace? I'm currently working it out for myself as much as I can, but help from someone that has done it before would rock! :)

yeah if you could that would be good. i realise there wouldnt be any correlation, but its just to see how off it can put some o them.

entering geek mode :)

[911f]

Old thread, but I just did mine today. That damn haynes manual has a picture clearly showing the wrong place to put the feeler gauges - thankfully vipers thread and this thread pointed that out to me. the text in the manual is correct, but i'm a picture kind of person.

anyway, to add, when measured in the wrong location, mine were consistently off by 0.04-0.06mm when measureing above the rocker vs. under the rocker - not sure I understand why that is, but it was very consistent across every valve.

thanks to this forum.

[Neosophist]

It's a good idea to measure ALL the shims while you have it apart too.. that way even if some don't need adjusting you wont have to faff around next time as you'll know the shim in there so just need to measure gaps :)

[Jono035]

I'm planning to check the clearances on my NC30 sometime in the next couple of weeks so I'm in here sponging up as much info as possible.

Viper_Biker: Thanks for the guide in the other thread, very useful info.

Oliherst: Cheers for posting this thread, I would have just followed the photos in the Haynes manual and done the same thing.

I'm getting the impression that it's worth going through and pulling all the shims to get a record of their sizes for future reference and I like having as much info on hand as possible.

It was mentioned earlier in the thread that cranking the engine round with the shims out is a bad idea so I'm wondering what the proper procedure is if you have quite a few shims that need replacing. I guess if you just buy them in new then there is no issue because you can leave them in until replacing them, but what if you want to do a swap? Do the cams have to come out in that case?