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I've got my 300 torn down and I'm about to send the block and crank out for machining, and need to disassemble the head and get that out for a P&P. I could have sworn that years ago I read about a guy in the OR/WA area that specialized in porting these heads, but for the life of me I can't find any information about it. Does anyone know what I'm talking about, or am I remembering things wrong?
IMHO, there is really no "rocket science" with regards to head porting to start with and especially an (any) oem cylinder head, only people who want to "market" their skills... any good machinist or even yourself can do this effectively and efficiently.
IMHO, there is really no "rocket science" with regards to head porting to start with and especially an (any) oem cylinder head, only people who want to "market" their skills... any good machinist or even yourself can do this effectively and efficiently.
Makes sense. I think the person I was thinking of used to race with 300s or something of the sort and so had good knowledge about P&P as well as other speed parts to help with power. But I could also be confusing them with someone else.
Larger valves are recommended to get a significant increase in flow especially the intake port.
Use a 1.94" intake and a 1.60" exhaust.
Your stock valves are 4.810"long.
SI valves sometimes carries the 1.94"/1.60" valves in the Ford 300 length. The 1.94" intake is part number SEV-2533 The 1.60" exhaust is part number SEV-3005
Otherwise you can use the Chevy 1.94"/1.60" valves which are 4.910" long.
Do the porting first so there is less chance of touching the newly machined valve seats
The port walls are thin so you just take a little off the port walls to clean them up.
Most of the work is done in the bowls to get the air to flow around the valve stems and guides.
Here is a good view of the intake bowl
As shown leave a vane behind the valve guide to direct the airflow
On the exhaust bowl just cut straight across the valve guide and leave a shelf before flowing into the port.
I like to unshroud the combustion chamber by installing the head on a bare block and scribing the cylinder bore on the head surface.
Then grind the chamber walls around the spark plug out to the scribe lines.
Shown below is a chamber with 2.02"/1.60" Chevy valves.
You will want to use screw-in rocker studs.
The only roller rocker that has the correct length to give you the proper rocker geometry is the Harland Sharp.
You can use the Harland Sharp Ford six 1.6 ratio rockers or the Harland Sharp Chevy six 1.75 ratio rockers.
The BBC rockers are .050" too long and have to sit way down on the rocker stud to get the roller to travel across the center of the valve stem.
Rather than using the Comp 268 cam that has a low valve lift use one of the other four cams in that range that have higher valve lift and stay with a 1.6 ratio rocker.
The 1.6 ratio rocker has less stress on the valve train than a 1.7 or 1.75 ratio rocker and the pushrod is better centered in the guide slot in the head.
The Comp 268 cam is detonation prone due to it's short advertised duration.
The cams listed above are presently being used by different members (fordsix.com) and show a strong power band from 1000 to 5000 rpm with a ported big valve head and tolerate a higher compression ratio (or lower octane gas) than the Comp cam.
I left Spokane WA several years ago. I was going to offer fully assembled ported heads before my move but decided to turn the project over to Bruce Sizemore (worldchampgramp2)
