Dicking with porting

[amceaglesx4]

If I give a good hogging on ports without getting into the bowls is it worth any decent horsepower ? I found out the exhaust could use a little more. Thanks

[Cheromaniac]

If I give a good hogging on ports without getting into the bowls is it worth any decent horsepower ?

No. "Hogging" out the ports, as you put it, could make things worse instead.
The valve bowl/throat/short side radius are the main areas that need to be worked in order to extract more power. Unless you really know what you're doing, it's easy to screw up and best left to the experts.

[6TIME]

X2 Bigger isn't better. You are trying to make the airflow more efficient in getting to, and past the valve. Smooth casting roughness and blend throat cuts into the bowl. If you are not sure what to do, either do a bunch of research so your efforts aren't wasted or have someone do it for you. Google pocket porting...
Good luck.

[amceaglesx4]

So far I've just smoothed out the exhaust ports and opened them a little. That's about it. My Mustang cobra heads I opened them ALOT doing the intake, bowls and exhaust ports. Just didn't know how far to go with the 4.0 head.

[Cheromaniac]

So far I've just smoothed out the exhaust ports and opened them a little. That's about it. Just didn't know how far to go with the 4.0 head.

You've barely scratched the surface. Here's what I did to the '95 head that I swapped onto my old 4.0 engine:

http://www.jeep4.0performance.4mg.com/head.html

I went further when I ported my spare '92 head and bolted it onto the stroker short block:

http://www.angelfire.com/my/fan/prep.html

[optmaxx]

Don't mean to hijack, but can porting the exhaust and intake ports be done with a Dremel? If so, what bits are recommended and do the valves have to be removed when porting?

[Cheromaniac]

Yeah you can use a Dremel. I suggest you buy the Standard Abrasives Deluxe Porting Kit from http://www.summitracing.com/int/parts/s ... /overview/ and buy a couple of tungsten carbide cutters for your Dremel to do the rough porting work.

[SilverXJ]

You could use a dremel, but it would take forever. Plus the SA kit won't work with a dremel.

[JeepsAndGuns]

I ported the heads on the AMC 401 in my 79 cherokee. It took forever with a good air powered die grinder, a carbide bit, and a port/polish kit from summit. I can not imagine doing it with a dremel.

[gradon]

I ported the heads on the AMC 401 in my 79 cherokee. It took forever with a good air powered die grinder, a carbide bit, and a port/polish kit from summit. I can not imagine doing it with a dremel.

X2--It took me about 25 hours on mine and a little less on my brother's. A Dremel would be madness.

[Russ Pottenger]

I ported the heads on the AMC 401 in my 79 cherokee. It took forever with a good air powered die grinder, a carbide bit, and a port/polish kit from summit. I can not imagine doing it with a dremel.

X2--It took me about 25 hours on mine and a little less on my brother's. A Dremel would be madness.

Very true. More time than most people realize.

Just a couple of quick thoughts on the subject.
First go ahead and get a small bottle of Dykem (machinist layout fluid) and scribe out lines using the gasket as a template. Remember air and solid liquids don't like to make turns. So try and remove material to straighten out the port.
The sides and roof are the most important.
The most critical area of the port is the area surrounded by the seat or commonly referred to as the bowl.
The problem is if you don't get the shape right, you can very easily decrease the flow rather than increase it. Remember air doesn't like to turn. After 18° Turbulence drastically increases. That's why cutter angles above and below the seat don't change by more than 15°.
So be very careful and conservative in the bowl area. Blend and radius the short turn of the port removing the least amount of material possible. When looking at the bowl area directly underneath the seat, Think of the shape of a carburetor Venturi, or radius of an airplane wing. These are shapes you would most likely want to replicate.

Lastly what's most important is a good valve job. Meaning that valve seats are concentric and have no more than .0005 run out. A good rule of thumb is the farther you get away from the seat the less critical it is to airflow.



Russ

[amceaglesx4]

Actual carbide bits are pretty bad ass. 10-15 bucks a piece. A fast Dremel would be madness.

[amceaglesx4]

Cheromaniac are you that Dino Saava guy ?

[SilverXJ]

A fast Dremel would be madness.

The sizes of carbide bits available for a dremel would be a joke for head work.

[Cheromaniac]

You could use a dremel, but it would take forever. Plus the SA kit won't work with a dremel.

I used my electric drill. Not exactly the best tool for the job but it worked for me.
I've ported seven heads and two intake manifolds using the same method.