Porting my 317s...
 

I am starting to port the 317s that I pulled off to put the LE heads on. I am shooting for a 15 to 20% increase in volume overall. I figure that will be fairly large in comparison. I was wondering, does anyone know how a 15% increase in runner volume will affect the increase in airflow? should I expect approx 15% increase in airflow or will it be more or less? I know there are other factors, valve size (I haven't decided if I am putting bigger valves in or not), airspeed and whatnot, but I would like to know how airflow is increased percentage-wise with respect to runner volume.

Also, does anyone have any recommendations for carbide grinding tips and good lubricants? Which ones are better than others, last longer, preferred tip shapes. I need to use metal tips initially, because I plan on removing a significant amount of metal. Any suggestions?

I have had great luck with the carbide bits available otc at fastenall stores, I think that they are nation-wide, hope i helped even a lil bit

definitely. thats better than ordering online. What do they usually get you per bit?

When looking for bits for porting aluminum, make sure the cutters are fluted for Non-Ferrous metal. Regular carbide cutters for Ferrous material will clog up quickly and you will spend more time digging aluminum out of the bit than you will porting. I like having a selection of 6" long shank bits as well as a set of 2" long shank bits. An assorted Cartridge Roll Kit (multiple diameters) with 1/4 in. Shank Mandrels in 60/80/120-Grits to finish things up.

For cutting fluid, one of the better products is made by Milacron and is called Cimcool (used to go by Cincinnati Milacron). Cimcool provides metalworking industries worldwide with a variety of coolants, lubricants, forming fluids, process cleaners and corrosion inhibitors used in the shaping of metal products. They have been around since the 1860's!

While most of their products are designed to be mixed with water to be used as a cutting/cooling fluid in milling or CNC machines and may be reasonbly hard to find for the average Joe, for doing small projects I like using the product in a small tub form, where you can just dip the bit in the paste.

That saved me alot of money right there...thank you!!! I like the look of the regular tips, they look less abrasive and more controllable, but I would rather have the right tip for the aluminum heads. I have an assorted kit (whats left of it) and there is a place in orlando that I can go and get individual rolls, which is nice. As for the grits, I stop at 120 when finishing the intakes, but I polish the hell out of the exhaust runners...figuring that it can't hurt. I haven't found any info to say thats a bad thing, so...

The cutting fluid, I haven't used anything yet, is there a significant benefit? Cutting tip life? Dust control? Tip control? What is the main benefit that you see out of it? Thanks for all the info man.

The main benefits are tool life and the greatly reduced the amount of aluminum that tries to stick to the bit. Especially when dealing with soft Non-Ferrous material, as you grind the material heats up, the hot metal will then stick in the flutes of the cutter. The cutting fluid, besides being a lubricant is a coolant.

A side benefit is as with any liquid, will be some reduction in dusting or metal flakes shooting everywhere.

Be careful if you're doing your own porting, don't remove too much, and try to maintain the shape of the runners, as that factors in to flow. It's not just the size of the runner that counts, the shape of it makes a difference also. :)

Well, regarding shape...I am doing a bit of "reshaping". The exhaust ports, I am looking to try to get a fairly large area right behind the valve, to assist with immediate cylinder evacuation, followed by a very smooth walled runner that will maintain its narrowest point in the middle of the runner, then funnel out to a larger exhaust port, trying to capitalize on the benefits of scavenging. The intake runners are a different story. I have been staring at them for a few days now, trying to figure out which direction to go. I am battling back and forth between shaping the intakes for airspeed or opening them up as wide as possible and using a cam profile that will generate a lot of vacuum in the chamber in the transition from the exhaust stroke to the intake stroke, and hopefully generate a fairly high amount of cylinder pressure. The second option is probably the best, because the heads will work well in a FI setup as well, where as if I screw up shaping the runners in the first option, the heads are all but garbage. Still undecided.

Good luck, post pics of your progress if you can :thumb: