how do you cut/grind them?
how do you cut/grind them?
With 'Mira' tools.
In sweden we call it that..
i have grinded special seats,,
how do you like 1 angle seats??
i tought so..
But connecting to this angle i have two radius.. = Optimal
Sometimes you are the bug
sometimes you are the windsheild
Forgive my ignorance, but , what the feck does that do then? and of course the golden oldie..........."What kind of power gains will I see?"
Clicky link for the longest (11 years and counting) rebuild thread..
Chip says..Bunch of jokers the lot of them, wouldnt know a good map if you stuffed an AA road atlas of great britain up their arse and set fire to it..
allows for easier heat disipation?????
(¯`·._'Keepin It Mk1'_.·´¯)
www.mk1oc.com - The Mk1 Owners Club!
Provides for a better gas flow and seal.
The ideal seat form is a continuous radius from the port to the combustion chamber, this eases the airflow across the seat and helps to improve the discharge coefficient of the seat, this is especially noticeable at low lift. If the guides are even slightly worn the radius seat will soon hammer and become wider, its part of the seats job to guide the valve head down to a seal, if the valve is at a slight angle to the seat it will wear the seat.
Creating a full radius seat is also very difficult to do so the next best alternative is a multi angle seat, sometimes this is three angle 60/45/30 degrees or 70/45/15, sometimes 4 and sometimes 5 angle, these are definitely preferable to a large wide 45 degree seat with a sharp edge.
Many manufacturers now produce their heads with a three angle seat as standard, the C20XE, Zetec, Rover K etc. all have 3 angle seats as standard, some even have a radius machined on the insert to help things.
Multi angle seats can be created using conventional seat cutting equipement such as Peg grinders, Neway cutters or similar. Care must be taken to ensure that the seat is wide enough (in the case of the exhaust seat) to provide sufficient area for heat transfer, as a guide the seat on the inlet valve should be around 4% of the head size, on the exhaust around 4.5%.
Once the inner cut has been made, this can be blended into the port to create a curve/radius as long as care is taken not to mark the seat. On some heads a small venturi before the inner cut can help further.
A similar radiused profile can be given to the back of the valve and in the case of exhaust valves the leading edge of the valve should also be radiused slihtly.
Last edited by DVAndrews; 01-01-2003 at 05:27.
Se7ens petrol head
(It's the voices that make me do it)
cant say i noticed 3 angle seat on my head when ive had it off. will never know cause it actually does have 3 angles now.