Originally Posted by TopspeedLowet
The lash will measure larger or looser when hot. The block and head grow and give greater lash when hot. The hotter temp you set the lash at, the tighter it will be when cold. Set the lash at the operating temp you run your engine at. Be it 200 deg or 160 deg.
Bruce
This hot lash procedure takes me a tick over 3 min from start to finish doing all 16 valves. I use the battery to roll the engine over with my remote trigger switch to my 90 deg marks and rock on thru in the firing order easily in 3 min. I leave the water pump on to maintain the heat soak and use my track temp gun to verify the engine temp. I'll bet that the engine block and heads do not loose 4 degrees during this entire process even with my all aluminum block set up. It is ok to do them cold like tod likes to. I used to do them that way as well. I had discovered on one of my oldsmobile engines that my cold extrapolation of -.006 from hot lash, was no where near where I thought it was hot when I had checked it a few times at temp. Some valves measured .004 loose or better hot, and some were not even close to the same lash as the one next to it. From that time on I did my lash at starting line temp and my engine ran faster and smoother than it ever had previous, I figured due to the lash being more identical at operating temp.
If you think your lifters and rockers are noisy you should hear my BBC coming back on the return road at 140 degrees. I thought that I broke a rocker the first time I heard that clattering. Lash makes noise, the more lash the more noise period.
Scooter, No matter which way you do them be it hot or cold, do them the same way every time to tell if there has been a actual change in lash and not just a thermal valve lash change.
Bruce