Predator valve adjustments

[Provff26]

So last weekend running my oval kart with a predator it seemed i was low on power. Compression tested it cold and it was down ten lbs compression compared to our two oter karts. Motor builder said check the valves. The were 3 and 4 thousandths. Stock call for around 6 and 7 (int and exh) so we changed them and gained the ten lbs compression back but im wondering if when it heats up will it be too off. Some other racers at the track say tey set valve lash to 0 and some 2 to 3. I know every engine is different but i figured you predator gurus would know better than the blue and yellow clone guys on the race forum for what is best for a predator. The engines are stock predators with an exhaust intake and rejetted. Governor removed

Thanks for the help cheers

 

[OzFab]

It doesn't take a predator guru to know that metal expands when it gets hot, meaning that 6 thou quickly becomes 2 thou once the engine warms up. If 6 thou cold is reduced to 3 thou, once it warms up, you end up with a valve that doesn't quite close, causing a loss of compression...

Of all the preformance tips & trick that I know, reducing valve clearance is not one of them, even on large engines...

 

[Provff26]

I guess ill just leave them as they are set right now. If its noticeably lower on power this week than last(god i hope not) ill reset them. I was noticeably down in power last week. Maybe the engine just needs breaking in, maybe it just a turd. Well have to see. What does everyone set theirs at and do you set them cold or hot?

 

[OzFab]

Cold!