intake matching to the heads

[Belgian1979vette]

As i'm fitting my itb's to my heads i found out they are horrible when it comes to the fit between the manifold and the heads.

First the manifold has pretty square ports, whereas the dart pro1's do not. Secondly the roof of the manifold needs to go up, and third the sides of the ports on the head are smaller than the manifold.

Did someone do a job like this and how did the tackle it ?

 

[Twin_Turbo]

Simply blend the head from inside the port, don't enlarge the short side radius too much where it flows into the bowl, same for the long side but not as critical. You can gradually open up the runner roof, and the bottom. Just don't go all out when grinding as you will do more harm that good most likely. A nice pocket porting would give some good results too. With widening the port entrance, be sure you don't break into the pushrod hole.

 

[mrvette]

Simply blend the head from inside the port, don't enlarge the short side radius too much where it flows into the bowl, same for the long side but not as critical. You can gradually open up the runner roof, and the bottom. Just don't go all out when grinding as you will do more harm that good most likely. A nice pocket porting would give some good results too. With widening the port entrance, be sure you don't break into the pushrod hole.

What he said!!!

 

[Belgian1979vette]

Simply blend the head from inside the port, don't enlarge the short side radius too much where it flows into the bowl, same for the long side but not as critical. You can gradually open up the runner roof, and the bottom. Just don't go all out when grinding as you will do more harm that good most likely. A nice pocket porting would give some good results too. With widening the port entrance, be sure you don't break into the pushrod hole.

I used this method to get a more accurate idea of port misalignment.

http://www.circletrack.com/techarticles/general/139_0305_port_matching_engine_porting/viewall.html

The problem is mostly on the short side of the port (side toward the middle of the engine on ports 3-4-5-6, and towards the outside on ports 1-2-7-8). The amount is something like in the range of 2 to 3 mm i would have to enlarge the port outward.
The manifold floor seems to match pretty well, but the roof needs to go up and leaves the edge a little on the thin side.

BUT then i have a serious problem with port nr 7 on the head. The outer edge (towards the rear of the engine needs to move a large amount out). The edge left for the gasket is to small imo. Plus the divide between 6 and 7 seems to have to move towards the outside also. However I could tackle the problem if i could add something like 2-3 mm to the outside wall of the port on the manifold and the outside wall of nr 6.

Anyway, the manifold ports look even in size, pretty rectangular and in the right position. Looks like something in the head is of. Maybe i should compare it to the victor jr i have here. Will do that tomorrow.

Did someone ever weld on an intake or would this be something you could fix with some epoxy. If so what type of epoxy. I have a feud with 8115, but seen the fact that its easy to manipulate to the correct size an make it smooth, it would suit the bill perfectly.

 

[clutchdust]

Simply blend the head from inside the port, don't enlarge the short side radius too much where it flows into the bowl, same for the long side but not as critical. You can gradually open up the runner roof, and the bottom. Just don't go all out when grinding as you will do more harm that good most likely. A nice pocket porting would give some good results too. With widening the port entrance, be sure you don't break into the pushrod hole.

I find this surprising. What is the logic here? Not disputing you, Marck, just thought that having more of a D shape with the wide part at the bottom of the runner would help maintain flow over that sharp radius. Is that wrong?
Glad I'm reading this before I start working on my heads.

 

[Belgian1979vette]

Simply blend the head from inside the port, don't enlarge the short side radius too much where it flows into the bowl, same for the long side but not as critical. You can gradually open up the runner roof, and the bottom. Just don't go all out when grinding as you will do more harm that good most likely. A nice pocket porting would give some good results too. With widening the port entrance, be sure you don't break into the pushrod hole.

I find this surprising. What is the logic here? Not disputing you, Marck, just thought that having more of a D shape with the wide part at the bottom of the runner would help maintain flow over that sharp radius. Is that wrong?
Glad I'm reading this before I start working on my heads.

Imo and as far as i know, the flow is highest near the top.

 

[clutchdust]

But isn't that because the radius at the top of the port is a longer, more gentle radius? I thought that was the whole point of opening up that short side, to try and speed that air flow up to match the speed of the incoming charge at the top of the port.

 

[Belgian1979vette]

Coming back to this. I was shifting the manifold back and forth. Seem that the best fit i can get with it, and having the common wall on the other ports aligned is when the common wall on the rear runners seems to be off.

Did anyone ever opened up a runners common wall and rewelded it ?