Stefano, When I rebuild my engine, the advice I was given was to make sure that the opening in both the head and exhaust manifold were identical. You did not want to have one opening smaller than the other. By using the hole of the exhaust gasket as a template, grind away on the inside of the mating lip any portion of the head/manifold that sticks out into the hole. No need to go too far deep into either unit, maybe 1/2" or so.
I used a carbide burr grinder bit in my air grinder which made fast work of both; I have stock cast iron headers. I did this when the engine was on the stand rather than in the car - it was easy to make sure any metal bits didn't get into the engine. There wasn't much need to take off very much metal on either the head or header. Bruce '73 GTV > Thanks everyone for offering all the suggestions. Lots of great > suggestions too. > > I had one more thing to ask. I didn't want to ask too many > things at once. Well, actually I just forgot. > > This is concerning the inner edge of the port on the manifold. > I have two sets of manifolds I'm preparing. One TS manifold > on a stock TS engine. One Nord on a prepared Dan Marvin > head. Engines are all in the car, so I don't have the liberty > of checking the smoothness of the mating area. > > Does it make sense to do any grinding on the inside of the > manifold at the mating surface on either of these? I wonder > how exact the head port and manifold port are to each other. > I wanted to alleviate the possibility of a step on the exhaust > side. I was wondering if the head prep on the Nord engine > has widened the port at all (I can't remember exactly the > prep, but it may have been just a polish on the exhaust > since I did not increase the valve size there). Since the TS > is stock, I was wondering if a little grinding wouldn't help > anyway, introducing a negative step. > > I was thinking about using one of those tri-stone things you > put on a drill and taking off a few mm of this edge. I don't want > to do anything stupid, so I would never attempt it before asking > those who know more than me. I have not even purchased > this stone attachment. > > I have never heard anyone discuss this, so I am prepared > for the wrath of the digest. Fire away if this is a bad idea > or just not worth it. > > Thanks, > Stefano -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
