Well the 56 272 I have in my ski boat is purring away happily, however she has slipped the same pushrod twice now (I don't think I adjusted it enough the first time) and I have a couple of questions.  I have purchased a 55 customline manual but it isn't very concise and doesn't cover anything on checking and replacing the lifters.  I have been told that the problem lifter may be collapsing, and this makes sense as there is a marked visible difference on the available thread on the adjuster (wound further in) compared to the rest of them too have the correct setting.  Does anybody have an electronic copy of a good manual for the y block that I can refer too, as I'm new to the motor and v8's for that matter, or recomend a godd concise manual to buy? 

Also is there anything else I should be looking for to gauge how much use this motor has had, and what may be needed, sorry for being pretty vague.  I recently bought it as a neglected ski boat for several years and have cleaned her up and as stated she is now running beautiful.  Now burnt valves, idles perfectly once warmed up, and ran for a good hour last weekend on the river just cruising around at about half to 2/3 throttle with no dramas, after the pushrod was re-fitted as it slipped after a couple of minutes of starting.  I didn't get right into her and I just wanted to ease her back in as she hasn't been run for years.   Too be honest I thought she would get up and go a bit harder at that throttle as it's only a 16' glass boat that's pretty light, that's why I think she may be a bit tired.

She now has new oil and filter, but when I had the sump off there was a bit of sludge in the bottom, luckily with no metal pieces found.  Does anybody recommend any of the additives that I can add to the oil that would help in removing/disolving any buildup in the oil system?  One side pumps like crazy, but the side (passenger side for usa) is no where the same volume, but does continually get oil at idle, with the suspected collapsed lifter having the least.

I apoligise for the simple questions but still learning my way around the motor and I don't want to get rid of the old girl as I simply don't have a great deal of cash and it fits perfectly with the old classic ski boat.

Cheers  Geoff, Downunder as well.

You could put air in the cylinder or a cotton rope to prevent valve from dropping inside, remove keepers, retainer and spring, then the umbrella seal. See if you can rotate valve by stem and see if there is any bend to it, make sure it is straight, If it is you could then take a cordless drill, install it on the tip of the valve and work it with penetrant (I like marvel mystery oil or tranny fluid for something like this) up and down slowly. do not drop it in the cylinder and do not come up with it hard on the seat. once you know it is free, blow off with air and soak with oil. reassemble.

That is if you do not want to remove the head.