Inliners International Forums General Discussion Engines GMC 302 Big Port Head

Here's a couple of photos of the intake port on the stock GMC 302 head. This is a cross section view and is an actual 302 head that was sliced with a band saw through the intake and exhaust ports giving a nice view. Many wonder what these things are really like inside so here's a shot of inside of an actual 302 head. You can all thank Arlyn Unrein of Russell, KS who had the wherewithall to slice up a scrap 302 head and send it to me all painted up so we can actually see what's inside this sucker!


Here's another view of it:


This gives you a sense of just what the inside of these heads really looks like!

AWESOME!!! Thank you, a great post! Any of the exhaust side? and and

Sure. This is not a good angle. If you want some better photos, I'll try to shoot a few tonight for you.


The intake is a little misleading in the angle; the head port is offset from the combustion chamber so as the fuel/air mix enters, it actually takes a 90 degree turn left then a 90 degree turn down to enter the valve opening. The exhaust on the other hand is split about in the middle (through the valve) and goes up and out with only a single 90.

The thing that surprised me was just how extensive the water jacketing is on these things.

Thanks to you and Mr Unrein for your work on this project. These pictures are immensely helpful for reference. An article detailing the exact specifications of the 302 intake and exhaust ports, illustrated with your photographs, would be useful in the *12-Port News* and might lead to some serious discussion about how to improve the 302 head for performance and efficiency.

God's Peace to you.

d
Inliner #1450

I can tell you that those cast iron heads are tough on band saw blades. I went through several cutting those cross sections.

If we are serious about an article, I stll have the remains of that 302 head, and could do some other cuts if necessary.