What cams are you going to be running? That will affect if you need different valve springs
Iirc Fred@btm can get these at a good price.
As James says, its cam dependant, but on 421s/438s you should be ok with standards.
They used to come with a stainless steel inlets and exhaust valves or stainless steel inlets and inconel exhaust valves but they stopped doing the stainless steel exhaust valves as they where no good for turbo engines so all that you can get now is the stainless inlets and inconel exhaust which is better.
Im sure Fred, ktec and Paul @ RS Tuning are more expensive tbh.
What's iconel?
So there's only one option now anyway, and that's the best?
Cheers.
Will order these as soon as possible
Its a coating i belive that allowes the valve to run at higher temps which boosted engines do.
Yes its better than stainless, i will be getting a set once im ready to have my head ported and my 421s fitted.
You wont have the problems with the exhaust valve dropping.
Inconel is a super alloy that can work reliably at temperatures from cryogenic upto about 1000 degrees C.
Its a great material for exhaust valves, although the supertech ones are two piece which is a slight weakness, but they are joined in a more sensible place for performance than a standard valve (further up the stem)
I thought Supertech valves were one piece???
Thought that was the main point in them lol
Like I said, joined further up the stem.
Like I said, joined further up the stem.
No point over springing the valvetrain, just increases parasitic losses and camlobe wear and gains you nothing.
You want the minimum spring that still properly controls the valve really, which in the case of 421s I believe is the standard spring.
As Chip said.
The 421 is on the limits of the standard springs.
For cams bigger than 421 where you need uprated springs, rather than get Cat or Supertech you could fit the 197/200 valve springs as long as they are within the spec required by the cams.
The gains on 421 are likely to be minimal though, ported heads are more important on hotter cams, will still help a bit though.
If you fancy getting a quote on some valves from the US I'd be interested as well...
Fair enough, I'll prob have a look anyway to see
the valves I put in Petes racecar engine are proper one piece
the valves I put in Petes racecar engine are proper one piece