fiestaturbo.com

[xrsi]

right am going to build myself a better spec head on a spare one i have and then sell my ported and polished large valve head with piper 258t2 cam...

is there only one size larger valve for the cvh and where is the best / cheapest place to get them from?

also what is a valve cotter?

[Oranoco]

I'd leave the valve sizes alone and would definately not fit the 285T2 cam. The profile is wholey unsuitable for the Fiesta RST (it's not all that clever on an Escort either). Be far better with a Kent CVH34 or 35 or better still a Newman.

[xrsi]

thats why i am changing the head, the one i have can go as a going concern. i am going to swap to a newman cam with the solid lifters.

however with valve size, larger exhaust valves will increase flow to the exhaust housing of the turbo and increase spool up reducing lag, hence why going for larger valve size on exhaust at least.

also the head will be alot better port matched to the manifolds to aid flow again.

[filtra]

I the haynes ford CVH tuning manual and pumaracing website it says that the exhaust valve size is very large anyway as standard. Wouldn't you be sacrificing low down torque anyway?

http://www.pumaracing.co.uk/CVH.htm

[Oranoco]

however with valve size, larger exhaust valves will increase flow to the exhaust housing of the turbo and increase spool up reducing lag, hence why going for larger valve size on exhaust at least.

Correct choice of exhaust housing would be far more beneficial than messing with valve size which will usually have a trade off effect. I'm still on stock valve sizes and the setup has done me good for a proven 256bhp

[BUTRE]

90% of the gains on the CVH head is made on the inlet. Exhaust only needs to have the std valve seat recut to a 3 or even 5 (if the tuner can do it) angle cut.

If you keep it 1.6 then going up to 43.5mm inlet valve is the best. Going 45mm is too much for the 1.6 displacement and by that a waste of money. 1.8 and 2.0 ZVH will need the 45mm inlet valve.

Pumaracing works very well the CVH head.

Also there is another company that are really a flow experts. It's not known in the Ford world but their work are really high quality standarts:
http://www.angel-works.co.uk/

[heeman10]

I'm still on stock valve sizes and the setup has done me good for a proven 256bhp

[devil's advocate] That doesn't mean that bigger valves wouldn't give you more power [/d.a]

[jonesy_rst]

a valve cotter is what holds the valve cup at the top of the valve spring. when compressed down u can release the cotter by spliting them and then u can remove the valve spring

[heeman10]

a valve cotter is what holds the valve cup at the top of the valve spring. when compressed down u can release the cotter by spliting them and then u can remove the valve spring

This is true (valve collets are used in pairs)...but why did you just write that?

[properphatboy]

also what is a valve cotter?

[xrsi]

so a cotter its half a collet then.... why not just bloody sell them in a pair for a valve and be done with it!

and james is right, prob get more power from slightly larger valve

[heeman10]

Cotters and collets are the same thing, and you need two to hold a spring in place.