Chain or Gear driven Cams?
TwinCam and M8 models.
If you are going to mount faster camshafts with a TwinCam, you should keep an eye on which type of TwinCam engine you have. It has to do with the year of construction of the engine. If you have a Twin Cam from 1999 to 2004, it is equipped with a straight double valve spring. The 2005 and 2006 Twin Cam models and 2007 to 2016 are equipped with "Beehive" springs which is a single spring and recognizable by its beehive model. The Beehive spring can handle more camshaft than the straight spring. So if you want a 551 lift or higher with a maximum of 585 in a standard head in the older Twin Cam models, you have to replace the straight standard springs with other ones! Always, no excuses.
The valve spring from 1999 to 2004, maximum 510 lift
The Beehive spring from 2005 to 2016, max 585 lift
The maximum lift is given by S&S, it may be that other brands deviate slightly, but it is a good guide when choosing a different camshaft.
I am going to mount the S&S kit 510-0227. With this kit you can go up to 585 lift in a Twin Cam head. To know what has actually changed in terms of valve spring pressure, I have a valve spring tester. In the race this is quite important, if a valve spring loses some strength the chance of major damage is considerable. My Buell that did an inch lift and turned 10,300 rpm had to put at least 1 spring in the trash after every run. The mounting preload on this racing bike was around 420 Ft/Lbs and pushed in around 1200 which is really a lot.
The S&S kit with S&S number 510-0227 consists of 4 beehive springs, 4 top collars, 4 bottom collars, 8 valve skewers and 8 spacers. It is advisable to order new valve seals immediately, fresh is better and you cannot change the bottom collar without removing the valve seal. What S&S wants is a preload of 130 Ft Lbs mounted when the valve is closed. If you arrive at a lower value after mounting, you must use the supplied tensioners to increase the tension.
With the valve spring pliers or another tool, remove the original springs, and I immediately remove the valve seals and the bottom collar. I clean the valve and cut off the carbon in the lathe. If the clearance between the valve guide and the valve is good, I mount the bottom collar, and the 2 skewers with the top collar, which I then pull up with my fingers. Now I can easily measure the size of the spring when mounted. You can also immediately measure whether the lift of the camshaft fits in the head. Since the lift is a maximum of 585, which means that the valve opens 0.585 "or 14.86 mm. You can also check whether there is room for your valve seal. Of course this all fits because the 585 lift is no problem in the Twin Cam head with Beehive feathers.
When measuring the original valve springs, the preload value was slightly over 100 Ft Lbs. The S&S Beehive springs were all 4 slightly above the prescribed value of S&S namely 135 Ft Lbs. All springs were exactly the same, so I didn't have to fiddle with the supplied spacers for a higher value. Now assemble everything with new valve seals and the heads are now ready for a maximum lift of 585.