1mm oversize valves

[snoopi2GSX]

Ok guys ive read pretty much every thread on here titled 1mm oversize cams and still have some questions i spoke to guy from a local machine shop about upgrading to 1mm os valves i just had the head built by the same machine shop i went with bc 280's ferrea comp 6000 standard sized valves bronze valve guides milled the head the works now im going from a 60-1 to a pte 6765 bb i fig i would benefit from the higher flow of 1mm os valves so i asked about port and polish and larger valves to get a price idea when i was quickly met with "you know you cant do 1mm os valves on the intake and exhaust side you have to oversize one side or the other" ive never heard of such a thing bfr can anyone on here please shed some light on this matter (now i dont know if this is correct and should i continue to trust this machine shop?) any help would be great thanx guys

 

[ChiTownHussla]

I MIGHT BE WRONG, so dont flame me, but I think its only the exhaust side that get the OS valves. This is to spool up the turbo faster? Just my opinion guys, B E Z

 

[snoopi2GSX]

Thanks chitown for the effort but ive only heard of people upgrading the exhaust side because the guides went out of specs but im also not 100% sure because i know a friend who ran 1mm os valves intake/exhaust without any problems that i know of

 

[chadnum1]

I have 1mm on intake and exhaust, they went in with no issues

 

[ChiTownHussla]

See, I stand corrected. Both can take the oversized valves. Hhope it helps !

 

[snoopi2GSX]

Ok this means I need to speak to someone else when I call back because maybe that guy didnt know what he was talking about but he definitely put doubts in my mind thanks a lot Chad for confirmation

 

[talontsi18]

I also have +1mm intake and exhaust valves. A good port and polish is needed to take full advantage of the bigger valves.

 

[BigBeans]

I'm not sure that's the shop you want doing your head work, because they're wrong.

I'm another one of the many with oversized valves on both sides.

 

[BoostedBeaver]

I too have the oversized valves on both. I only got them because I had to get a valve job anyway so they already had to cut new seats. In my opinion, you can keep the stock valves and be fine but if you want to upgrade by all means do so.

 

[kchaazz]

Id definitely consider taking your head somewhere else, as these guys dont seem to be very familiar with DSM stuff
My friend (BOGUSSVO on this site) does DSM heads all the time and Ive watched him do it. In a nutshell, the valve seats are cut to accept the OS valves. Course, there are other things that this shop probably WONT know, and may not even check, like proper installed spring height, spring pressure for YOUR springs, amongst other VERY imoportant things that could make the differrence between a good performing valvetrain and a catastrophic failure. If it were me, Id check around to see if there are any DSM shops within driving distance

 

[954TalonTsi]

Your machine shop has amatures. All they have to do is cut the seats, and youll have OS valves like the rest of us. If i were you i'd find a better shop.

 

[snoopi2GSX]

Update: by the way thanks guys for all your answers I appreciated very much well it turns out the kid I spoke to is a newbie at this machIne shop I managed to speak to the guy I dealt with before and were all good I'm getting nitrided supertech OS valves on both sides he even offerred to give me a deal if he supplies the OS valves so I'm going with it