valave cover performance on atc 70

[oneroom42]

i have seen the billet valve covers with holes in to relieve pressure and add performance. does anybody have these and did they notice any difference? or has anybody just drilled a hole in the stock valve covers and noticed a difference?:wondering :wondering

[KASEY]

on stock bore engines it makes no difference,, when you start getting above 125cc its just a breather ,,, so it helps keep the crankcase pressure down,,,

[mustangmachanic]

where do i drill this hole? i have too much crankcase pressure where is the factory crankcase vent?

[oneroom42]

on the atc 70 there are valve caps with a hex head in the center for removal. the billet ones looked the same with a little open nipple in the center of that hex. i cant seem to remember what site i seen them on, or i would send you there rather than have you drill out four stock ones. i do kinda remember the billets being around $30.

[big_daddy124]

just curious why would you drill out 4 of them on a 70?

[big specht]

I drilled out mine on my atc I did notice a change . I end up JB welding a brass nipple in top so I could mount a filter the only thing I ran in to was valve clearance with the brass nipple it was hitting the adjuster nothing a little grinding wouldn't fix:)

[oneroom42]

i just read my reply and i was also confused as to why i said four stock ones. i guess my mind was going somewhere else when i was typing. A D D sorry about that!

[freaksfix]

I seen an ad in an old 3 wheeling mag years ago when i built my basket case 70 for these vented caps. So i just drilled one and tapped it for a brass fitting and put a section of gas line for a vent.. Not sure if it did anything perfomance wise, but in my eyes if you can cool the motor in any means it has to do something you might not beable to feel the differance but at the very lease you will be impoving the life of the motor i would think..