De4n0

Ok so im going to be rebuilding my 2.0l zetec head for my zetec turbo build and have an rs exhaust cam, 1.8 inlet cam, rs exhaust valves and uprated springs.
I would like to port and polish the inlets and make sure the valves seat properly, can anyone give me any advice on the best way to do this, ive seen a video on youtube of someone using a suction stick and a cutting compound to seat the valves, is this good practice?
Any help would be great, thanks, dean.

mk1 rob

iTrader: (1)

Hi,
Yes the suction stick is the way to go. Any good motor factors should sell you the stick along with a pot or two of cutting compound (usually one courser and one fine) Just be careful around the seats if you are porting the head yourself as a little score with the porting tool can take ages to take out with the cutting compound.

Also if you have the time try to round off the lip on the valves at the edges of the seat area. I find this can add almost as much power as the headwork itself. I put valves in a pillar drill which makes it nice and simple.

And port the head, dont polish it. Its a generic term which can be a bit misleading. you want a smooth finish but not shiney or fuel will drop out of your air fuel mix and beed on the shiny surface. I normally finish off ports with an 80 grit flappy wheel which leaves the desired finish. Also as you are turboing your engine make sure all sharp edges are removed (rounded off) from the combustion area or you will get hot spots glowing which can cause detonation which will soon destroy all of your hard work.

Hopefully some of that helps.

Rob

xr-stu

ive heard of 3 angle valve seats obviously but never heard of that before. makes sense to do it but do you really believe it makes a noticable difference? im planning on doing some DIY porting to a 1.7 puma head of mine, only mild stuff, but would it really be worth doing that? what about machining down the stems slightly at the same time? worth doing?

mk1 rob

iTrader: (1)

3 angle jobs are for the seats but the same principle applies. 3 angle seats are better than single but blended seats are superior again. Don't try to waste the stems of the valves, either buy wasted stem valves or leave well alone. They could become weak and snap the head off at higher rpm and if you haven't seen what happens when a valve head comes adrift it usually puts a hole in the piston then gets embedded sideways in the seat. Not good.

xr-stu

makes sense. no harm in smoothing the valve head though, will give it a try.