Well, I got off the phone with Rick Hobbs and Brian Ucheata (sp?) today. Brian is an American Honda road racing guy but mostly dealt with the works parts not the kit parts. Rick built many SP1's with kit parts and had some memory of what he found out, here is what they remember. Brian says he has never seen any HRC valve seats that where Ti, they have all been steel. Rick seems to recall the HRC SP1 seats where thinner to allow more valve lift with out the springs going in to bind. Rick said from what he remembers you could not run the HRC cams with the HRC springs and retainers with out the HRC seats with out binding issues. With the lift of Dales cams there is no problem with spring binding with the OEM seats. Rick could not tell me for cretin but he believes the inner seat may have a slightly different diameter to fit the inner spring better and prevent the spring form walking around and causing wear to the seat or spring. As I said, Rick is going off his memory and the only way to be 100% is to install and measure for yourself. I have a set of HRC seats ordered so I will be able to compare them to the OEM seats soon.
It gets a lot more complicated but to sum up our discussion...
-The HRC springs have less installed seat pressure then OEM and require less valve mass to prevent float. The Aluminum HRC Retainers help a lot.
-The OEM springs will go in to bind with any more lift then the OEM cams.
-You must use the HRC retainers with the HRC springs and if you run in to binding issues with the OEM seats you will need the HRC seats.
-The HRC cams require the HRC seats to prevent spring binding.
-You may be able to get away with the OEM seats but it would be wise to check for wear on the seats after 100 miles of hard running or so.
-If you dont have the Ti valves it would actually be better to run the OEM (thicker) seats as long as there are no binding issues to help add spring pressure and prevent valve float. This is especial true with a rev limiter above OEM.
There, I hope that all makes sense.
Neither had any info on the -700 spring part number but both guys said stick with the -000.
I am still waiting on one or two other sources that may be able to back this up (I love redundancy).
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