Update 3: Valvetrain Setup.
Continuing the processes of measuring everything carefully, I tore down some new-in-box boss 302 CNC cylinder heads to upgrade the valve springs and retainers (and additionally some arp cam tower bolts to replace the small torque to yield bolts that are truly meant for one use only).
Valvespring Selection
I selected the PAC Racing Springs 1234x Coyote Drop-In spring. Drop in means that it should be install-able without significant need to measure or shim the spring or use an aftermarket retainer or base.
The stock boss spring has an installed height of 40mm or 1.575". The rate is supposedly 67lbs at installed height, and 157lbs at open (which is undefined). Rate is approx 190 lb-in (anyone feel free to correct me, math feels rough here)
The PAC spring has a similar install height (I did measure a slightly taller difference due to the titanium retainer design being different than oem). 92lbs at installed height of 1.575 (mine was 1.585), and the open height of 1.050 has a load of 218 lbs for a rate of 240lbs-in.
These rates come into importance when dealing with aftermarket cams which can have different ramp rates. I'm using an OEM boss exhaust cam, but a custom L&M intake cam (Which is similar to stock with slightly moved events).
The weights are also different: the Factory spring and retainer weighed in at 1.73 ounces, the PAC spring and titanium retainer weigh in at 1.52 ounces. Hopefully shedding 6.72 ounces from the valve train proves beneficial.
Final Note on selection: Titanium is a high wear rate material in this application. Yearly replacement is recommended per Ford on the FP350S. I'm going to see if I can push that to two years, but its not a huge cost. The springs would be checked at the same time and would be replaced if they fall significantly under their spec. Usually boss springs are a yearly or bi-yearly replacement item (though I've never made anything last a year personally), but this may allow longer intervals.
Spring Replacement:
The process is pretty straight forward, but time consuming. The tools needed are a valvespring compressor (I borrowed one from
@ArizonaBOSS ), a 14mm socket, 3/8" long hex drive socket, a magnetic pickup tool, 8mm socket (for cap bolts), and paint pens for marking.
The process (for head on a bench) is:
- label / validate cam caps and remove them from the head
- Install the tool base and arms over a set of valves to be removed
- Tighten down the main bolt on the tool to compress the spring and expose the keepers
- using the magnetic pickup tool makes it easy to grab the keepers
- undo the compressor bolt to release the valvesprings and retainers. Remove the assemblies
- install in the new springs and retainers
- Compress them using the compressor tool (this was difficult with the exhaust side, as the bolt was too short to start without hand compressing the assembly)
- With the springs compressed, carefully replace the keepers back on the valve stems (the pickup tool was used plenty to get dropped keepers out of the head). Also the valves are free to drop down, so be sure to seat them, I used a paper towel folded up under the head to hold them up in the chamber bowls.
- slowly undo the compressor tool and watch the retainer capture the keepers
- Take final measurements, and mark the completed assembly with a paint pen (I also measured the tops of the valves to ensure all keepers were properly seated as I marked each one).
Both heads took me about 4 hours altogether. On car it would be even longer, removing the cams and ensuring to put each cylinder to TDC and pressurizing them with air to hold the valves up. My biggest tips are go slow, measure everything carefully.
I also took the time to install the arp cam cap bolts. I see a lot of value in these as the caps require careful torquing to properly retain the cam and maintain its clearances. Additionally the arp kit is reusable where the oem bolts are TTY / one use only.
Some Photos of the process:
FP350S oil galley mystery:
I have also been looking at why Ford Performance chose to tie the left and right heads together at the backs of the oil galleys (from intake side to intake side and exhaust to exhaust with hard -6 AN line). Its definitely a balance thing, however I'm working to get answers. I have validated that common 3/8" NPT to -6AN adapters fit well in this application for the threaded ports on the heads, but I until I get a final word from FPP (who have no reason to provide any useful information), I'll leave the heads alone.