Alright, im porting a set of gm441 heads that have been machined for 2.05 valves, and so where the valve job meets the the bowl there is a slight lip. i dont know how to post pictures or else i would post a crappy illustration of it. But i was wonder if i can grind the lip down that way there is a smooth transition from the bowl over the valve job and seat. If anyone is willing to email me for the pic, i would be very appreciative.

 

I think what you are referring to is the throat cut which makes the inside of the valve seat larger in diameter to maintain a ratio between valve size and throat diameter. This cut often leaves a lip just above the valve seat angle, and yes you can blend it smooth and it should produce good results from considering it's very easy to blend into the bowl area.

Mike

 

does this go for the lip all the way around, or just at the end of the bowl?

 

If it left a sharp edge with the short side radius, blend that also, all the way around. The actual seat cut can leave a sharp edge also where it enters the combustion chamber. If you have an old un-used valve laying around, put it in the guide (so you don't nick your new valve job angles) and blend into the combustion chamber. If you have a head gasket to use as a template, you can scribe the edge of cylinder onto the head, and unshroud the valves while your at it.

I have a link to a write up I did on head porting, complete with pics if you're interested. It deals with LT1 specific, but a lot of the same principles apply.

Mike

 

Heck yeah! i'll take all that i can get. but wait.. on the blending to combustion chamber thing. you mean i can grind down that edge? isn;t that the valve seat?!? and i would think that messing with that would risk pressure being leaked into the runner when combustion occurs.

 

Here it is: http://members.***.net/gmarengo/

When the page opens, click the DIY Porting on the left.

Please keep in mind that this is not my page, just the article I wrote up a couple years ago to try help the "do it yourself" crowd. When I first wanted to port my heads, I came accross a LOT of skeptism and reluctance, not to mention lack of information. I did quite a lot of research and tried it, got lucky maybe and decided to do a write up on it since I took pics of the the head in progress. Since then, I've ported quite a few LT1 heads and picked up a lot more info as I go. I learn something new just about every time I port a set.

Email me directly if you have any particular questions. I'll try to help if I can although it's hard to describe things like this over email sometime. Good luck. Use this email: mhankel@pivotalcomm.com

Mike