Gt40 Headporting....

[Alex Kraczek]

Before I start, no, I did not do any research on this topic as Im assuming such a strange question does not come up very often.

My question is this- how hard is it to port GT40 heads, and make them flow worse...not better?

The reason I ask- I picked up a set of gt40 (not P) heads for 50 bucks. I ported them pretty thoroughly, no polishing. I took down the valve guides the best I could, and opened up the bowls quite a bit as well. I stayed away from the floor for the most part, cleaned them up a bit thats all. Cleaned up the intake side as well, taking the guides down. My question is this, I hear alot of talk about opening up the bowls etc.... can you make them worse? Just curious, I trust my work but again Im no expert...

 

[stykthyn]

If you alter them in the wrong areas you will actually hinder flow rather than promote it which will make them flow worse so, in a nutshell, yes. Contact @tmoss he is the porting guru.

 

[jrichker]

See diyPorting.com it says GT40P, but the basic principals should be the same.

 

[a91what]

Cleaning up the walls is ok, in all the short side radius is most important. Never touch the floors. Bowl work is fine and encouraged, leave the area tward the port in a tear drop shape at the guide this promotes velocity. Take off all casting flash and blend the bowl into the port, use a gasket of your choice.

 

[84Ttop]

Without putting your heads on a flow bench, it's a shot in the dark as to whether you made and improvement or not. I've seen plenty of DIY port jobs that have seriously hindered performance, for that matter I've seen some of the top names in drag racing engines playing with new heads and making them worse before figuring out just what to do. Granted, these guys usually invest countless hours into porting a set of heads and have years and years of experience. Long story short, coming from a guy that does damn near everything myself I don't port my own cylinder heads

 

[Alex Kraczek]

Thanks for the input guys. I am going to hopefully clean them up some more in the near future, and go for the teardrop shape as much as possible.