Quote:
Originally Posted by Texas Pete
Too tight as in no movement. All engines heat up and the metal expands. The thermal expansion when running means that when the engine is cold, the valve clearances will be at their largest. Hydraulic cam followers were put into modern engines to prevent tapping noises as the engine heat up they adjust with the increased heat, but they don't exist in our Chinese Honda clone engine. If you have tappet rattle at full running temperature then you can reduce the clearance within the specifications range. Just keep in mind if the gap is too large the tappets will rattle, but if its too small the valve will not close properly when hot, and that can lead to misfires and burned valves.
|
That's a good explanation of valve clearance in a cast iron pushrod engine but it doesn't necessarily apply to a cast aluminum engine with OHC and rockers mounted to the valve cover. While true that metal expands with heat, which expands more; the valve stem or the aluminum valve cover?
Anyway I'm glad you didn't run too long with no valve clearance. Mine was luckily perfect from the factory.