I have a set of Dart 180's that I am planning on porting. I have seen the Standard Abrasives web site, but I also realize that porting techniques are typically head specific. Can anyone give a walkthrough of problem areas and other areas of restriction that could be cleared up in the dart 180's?

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355 c.i.
Dart 180 Heads
Lunati 224/224 cam
Harland Sharp 1.5 rockers
Performer RPM Manifold
Holley 600 cfm double pumper
Hooker Super Competition Headers
Flowmaster Exhaust
Competition Engineering Sub-frame connectors
Super T-10
GM posi 3.42 rear
Hurst Roll Control
13.9@102

 

THere's not much left to do around the valve seats. Dart did a good job with them. Just blend all the sharp edges where the CNC-machined parts of the port (near the seats) meets the base cast parts of the ports. That's about all you can do to them without getting seriously involved. Dart did a good job getting the most critical flow areas right- 1/2" before and after the valve seats.

You could probably smooth out the areas around the valve guides a little, too, but they aren't that bad to begin with.

Backcutting the valves is also a good way to gain some flow once you have determined the exact relationship between the valve and it's seat.



[This message has been edited by Damon (edited September 13, 2001).]

 

Well, there is definitly room for improvement. Dart heads flow something like 208 cfm at .400'' and 209 at .500''.I'd be happy with about 10% cfm improvement on the intake and exhaust. If there are any flowbench numbers, before and after porting that someone could post, that would be great. Pictures would also be excellent.

 

Well, there is definitly room for improvement. Dart heads flow something like 208 cfm at .400'' and 209 at .500''.I'd be happy with about 10% cfm improvement on the intake and exhaust. If there are any flowbench numbers, before and after porting that someone could post, that would be great. Pictures would also be excellent.