Hello, I´m planning to do the valve adjustment in my 308 QV and have some questions for the experts. Do you think I´m too optimistic if I try to do it without removing the camshafts on a 4 valve car? The cam seals have not any leak, so I would prefer not to change them. The other question is probably a silly one: When measuring the clearance on a lobe, the piston should be on TDC. That means that all the valves are fully closed. Then you have to press over the shim with the special tool to give clearance to take the shim off. Well, if the piston is up (TDC), and you´re moving the valve down, is there any risk to touch the piston with the valve? I assume that when you press over the shim with the tool, you don´t fully open the valve, so there´s enough room over the piston to allow the valve move down a bit, but I´m not sure. What are your experiences? Thank you
I have always rotated the cams until the lobe is 180 degrees away from the tappet. Spark plug removal makes this easier in case you have not done that. I have done it with the cams in and the cams out. It's easier to remove the tappet with the cams out but removing cams is a lot of work. Never had a valve hit a piston with lobe pointing up.
The "TDC" part is where you are making an error. If both the intake and exhaust lobes are generally pointing up (say at ~10 o'clock and 2 o'clock), you are much farther into the power stroke so the piston has descended a fair bit down the cylinder. At TDC, either the intake valve would just be opening, or the exhaust valve would just be closing (i.e., the corresponding lobe would be pointing downward at about the ~4 o'clock or ~8 o'clock position, not up).
This, take the plugs out & stick a 36mm socket on the damper bolt & rotate the engine till the lobes for each valve point upwards (there is some margin for error on this but remember the valves are set at an angle in the head) & measure. Write it all down & then repeat. WIth the cams in, the manual says to use compressed air to remove the shims (once you have levered the valve open with the tool & held the bucket down with the hook thing) but a small pick and a magnetic tool thing should help you get them out. When you take the shims out don't believe what is stamped on them - measure them as well with a micrometer (and you will find they seldom match up with what is stamped on them!) Inlet valve clearances should be 0.20-0.25mm For the exhausts there is a debate. The book says 0.3-0.35mm but there is an argument to suggest that's wrong & they should be at 0.35-0.4mm. I don't think its that critical but the last time I did mine I set them all at as close to 0.35 as I could. Depending on how far you want to go you could consider a) measuring all the clearances b) removing the belts & cams & then measuring the shims. c) Make a map & swap shims around to give yourself the best / most even set of clearances you can (and probably end up needing to source 2 or 3 new shims) d) If you do that then with the cams out its a good opportunity to replace the camshaft oil seals. This will then give you a map of what shims are where in your engine that you can keep & you can then swap shims around to try & give yourself the best/most even set of clearances you can. As things wear the clearances will close up (but this should happen very slowly) so if you set everything towards the upper end of the range then you know you will have a good long period of running before you need to do it again - and when you do, you will know what shims you have got & where they are in the engine. If you find an inlet valve at say 0.20 or 0.21 , while its technically in spec, I took the view that I'd try & find a way to swap some shims about to open that out to .23 , 4 or 5 & that's what I did. As above, all my exhausts were 0.34 or 0.35 the last time I did it.
That means that when pressing on the shim, this piston should´t be on TDC, it should be in a position in wich the lobes where at 10 o'clock and 2 o'clock to be sure that the piston is not in the highest position. I´m right?
Basically yes but I don't think you are going to be able to bend a valve by hand doing this so I wouldn't give it too much thought or worry about valves hitting pistons (and they don't). If you are going to take the shim out from under the cam then the lobe needs to be pointing up & out the way in order to do it, you don't have much choice in the matter! Engine TDC is not really relevant with this process although obviously with the cams in you do this with the belts still on so that you can maintain the basic engine timing as you work your way from one valve to the next and clearly you don't rotate the engine with a shim out.
Another great thread with a wealth of tips. I have always just taken the cams out. I don't think it's much work at all. Especially if the alternative requires posting a thread or worrying about how you're going to get a shim out. Then not knowing what shim do you need and doing them one at a time can be a challenge for the DIYer. I have only done this at the 5 year mark when I'm changing the belts and figure the cam seals should be changed, too. I do all my measurements twice (some recommend 3 times) and record the values. I remove the cams. I then measure the shims out of spec with a micrometer and calculate what shims I need. I go buy the shims I need at the Volvo dealer since they are compatible with the old Volvo 240/360/740 gas engines (I have a 2V car). Then I measure the new shims with the micrometer because nothing in this world is perfect and the new shims won't be either! And when all is done I check the clearances yet again. Though, having done multiple measurements before removing the cams and double checking the size of the new shims I have had no surprises when taking the last measurements.
Try this to help along. I use it. No issues to date. It calculates for you automatically so some cells you cannot type into. ** No warrenty is expressed or implied. ** Image Unavailable, Please Login
