Vintage Mustang Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
1,794 Posts
Discussion Starter #1
Before is on the left, and after is on the right

http://home.comcast.net/~dciab/VMF/before_and_after.jpg

I know the pictures are kinda blurry, but you can get an idea of what I did.

- Ground down the big bump, is that the "EGR" bump?
- Hogged out the exit to closer match the header ports (my header flange openings are actually slightly bigger than the gasket opening, so I am actually making it better match the gasket)
- Smoothed out the area where the valve stem pokes through
- Smoothed out casting seams in the port

This is just the "roughing out" stage, I will go back and smooth everything out with the sanding rolls later. But as far as port jobs go, how does it look (besides blurry)? I wasn't planning on doing much of anything to the intake side except smoothing out where the valve stem pokes through.

Give me your opinions on what you see and what I can do to make it better. Also, what amount of porting would you say that is? Port match, thorough, generous, massive, gargantuan?
 

·
Registered
Joined
·
3,897 Posts
It looks really great! Did you use a die grinder to accomplish the task? What kind of bits?

I'm head porting dumb, so please correct me... On a street driven engine which does not live in high rev land, its my understanding that you want to focus on porting and polishing the intake side, to provide a much smoother air/fuel path to the cylinders. And to not port too much on the exhaust side. If the exhaust side is ported too much (port matched), you reduce your exhaust scavenging (or backpressure), thus losing low end torque.

Am I wrong with this way of thinking? I too, want to port a set of heads, I just need to know that I'm doing it properly for the appropriate engine application, namely a non-raced mainly stock street engine...with a Paxton!!!! ::
 

·
Registered
Joined
·
3,514 Posts
Keep going! Cast iron takes forever, huh? Here's some pics of an SBC 'display' head this guy who working out of my buddy Rich's machine shop. I think he finally got the flow bench set up if you want to check your work when you're done.

Here's some downloads that might be helpful:
http://www.sa-motorsports.com/diyguide.shtm

Good luck!

Robert
 

·
Registered
Joined
·
3,971 Posts
These are the basics that I work by.
1.clean the valve pocket up.
2.reduce and taper the valve guide.
3.widen the short turn radius by about .080 especially toward the bottom of the port on each side.
4.smooth and blend the short turn radius.
5.remove the thermactor inlet bumps.
6.gasket match the end of the port and blend.
7.triple valve grind.
8.a nice set of aftermarket valves.
Keep in mind that I'm no expert myself.
 

·
Registered
Joined
·
1,794 Posts
Discussion Starter #5
Those SBC heads look nice, but I don't think I can get mine to look like that!

The SBF heads are kinda weird with that big 'ol thermactor bump in the way (see drawing 1 for an exaggerated example), and I am afraid to take more out of there. I have reduced the bump to a ramp, going straight from the opening to the valve guide boss (drawing 2, exaggerated). Are you suggesting that I keep going and get something like drawing 3? I am worried about what is lurking under that ramp, or rather what isn't lurking.

http://home.comcast.net/~dciab/VMF/ports.jpg

Has anyone else taken that ramp completely out while porting?
 

·
AKA Exchevman
Joined
·
5,383 Posts
It looks really great! Did you use a die grinder to accomplish the task? What kind of bits?

I'm head porting dumb, so please correct me... On a street driven engine which does not live in high rev land, its my understanding that you want to focus on porting and polishing the intake side, to provide a much smoother air/fuel path to the cylinders. And to not port too much on the exhaust side. If the exhaust side is ported too much (port matched), you reduce your exhaust scavenging (or backpressure), thus losing low end torque.

Am I wrong with this way of thinking? I too, want to port a set of heads, I just need to know that I'm doing it properly for the appropriate engine application, namely a non-raced mainly stock street engine...with a Paxton!!!! ::
From what I understand, you want the intake to be rough to better mix the air and fuel, you want the exhaust to be smooth to let the motor "breathe". I'm no expert, some one else, please chime in.
 
1 - 9 of 9 Posts
Top