Big Will_

Just ordering some new oversized valves for my ST170 head and i need a 6.02 and 6.03 internal diameter valve guide - however the manufacturer of the valves don't make the guides.

Is it possible for a machine shop to ream the standard ones out when i send the valves over to be cut in?

Red16

cant see why not

Turbo Zetec

iTrader: (1)

yes, see it done every day!

Big Will_

The valve guides don't have any coatings or anything on that will need re-doing and it won't damage the new valves?

These valves ain't cheap and i don't want it going wrong

Chip

iTrader: (3)

It will be fine, although obviously the valve guides will be less sturdy as a result, but if they are 5mm ones anyway, .5 mm thinner walls isnt going to matter I would imagine.

Turbo Zetec

iTrader: (1)

ah, now, are they shiny stainless valves? if so, you'll probably be wanting to fit some bronze guides or some k-line (or similar) guide inserts.

just out of curiosity, what size are the valves? and are the stems the same size as the standard zetec?

Big Will_

They're Ferrea +1mm oversize inlets and exhausts.

The stems are 6.02mm and 6.03mm.

They're the Competition Sport Valves made from a 'special alloy'

Would it be worth telling the machine shop to change them to bronze then ream?

Rick

u need to check the stem material, as some are very abrasive and will wear the guide out. You can overcome this problem by having a scroll cut into the guide for extra lubrication.

Rick.

tabetha

Stop worrying this is kids stuff to a half way decent machine shop.
tabetha

richard_syko

I always though broze guides had to be reamed once installed as they contract when pressed in. Could be totally wrong though.

JTECH James

iTrader: (13)

a good machine shop will always check and ream the guides after fitment

Big Will_

Well - an insert would HAVE to go in first as the standard stem diameter is 6.06 and the aftermarkets are 6.02 and 6.03 - so i need some more material in there!!