'48 288 Valve Lash

Posted by DavidPackard On 2017/4/24 21:54:58

Does anyone have a recommendation on cold valve lash settings for a '48 288 (solid lifters)?

I know the recommendation is to adjust the lash on a warm engine, but I don't see myself finishing a valve adjustment in the amount of time it would take for the engine to significantly cool, and the idea of reassembling to rewarm seems a bit odd. Plus I would like to 'take all day' crawling around on cardboard without getting a lot of oil on the cardboard.

For the '48 288 there is the original lash recommendation and then a later Packard recommendation to help reduce 'valve clatter' . . . they reduced the lash about 0.002 on both valves (see Service Counselor 22-12). The 'new' recommendation is 0.006 for the intake, and 0.008 for the exhaust.

I searched the internet on this subject and there is plenty of advice for overhead valve engines with all of the possible combinations of block, head, and pushrod material choices, plus rocker arm ratio. As a result the delta valve lash between cold and hot varies quite a bit. The question I'm asking should be based only on the differential temperature between the block (coolant temperature) and the valve, plus the valve length. I did a quick calculation and convinced myself that we may be talking about 0.002 clearance reduction for the exhaust and less for the intake . . . perhaps just set the original clearance (pre- SC22-12) cold and 'call it a day'.

I would like to hear from those that have some 'first hand' experience in this area.

dp