Valve clearance help

[Gs425FridayHarbor]

Hi all,

Finally checked valve clearances on my 79 gs425 and all shims are 2.7mm with no.2 intake at 2.65 mm. I could not get my .02 feeler gauge in any of them, so I was going to reduce all by .08 and order replacements from the shim club. Is this a safe guess? Since .02 is the smallest gauge I have and figure a little extra clearance might be okay, I was just going to reduce all by .08. Any thoughts greatly appreciated!

Also, when checking my exhaust shim on no. 2 I noticed a lot of oil pooling when I released the tappet depressor. Do you think this means valve seal replacement neede on this valve?

Jamie

 

[tkent02]

The shims only come in .05mm increments, you can't just go .08mm smaller. Do this, see if the shim bucket will spin in it's bore with light finger pressure when the cam isn't depressing the shim. If the bucket will spin easily there is at least some clearance, so go one size smaller, .05mm. Replace the 2.70 shim with a 2.65 for example. This should leave you with something over .05mm clearance.

If it won't spin at all theres less than zero clearance, go two sizes smaller, which is .1mm. Replace the 2.70 shim with a 2.60. This should get them all in the ballpark. This should give you at least .05mm clearance on all.

Might leave you with a few above .08mm clearance, might be up to .10mm, but that's OK. A lot of us go for .05 to .10mm clearance anyway. It works fine.

The ones that won't spin could be so tight that a .10mm thinner shim still doesn't give any clearance, if so do it again. Usually that's not the case on engines that run OK, it they were that tight it likely would have burned the valve.

The oil in there is normal, oil flies all around in there from the cam chain when it's running, it just doesn't drain out.

 

[Gs425FridayHarbor]

Awesome. Thanks for the help. I was able to spin all of the buckets with finger pressure but one, so will proceed as you suggest. Thanks again!

 

[Guest]

You already have one shim that is thinner than the rest. Take it out, put a quarter in its place. Move that thinner shim to the other positions one at a time, measure the clearance there. You will at least be able to see if one size smaller will be enough or if you need to go more.

If you don't have a quarter, use a nickel, half-dollar or even a silver dollar, but put SOMETHING there or you will damage the edges of the cam lobe.

 

[Nessism]

One other thing, once you figure out what shims you have and will need in the future, I'd order up a selection so you can keep them on hand. Z1 Enterprises sells shims for about $6 each so stock up.

 

[tkent02]

Or save some money and get them from Ray.