There is a lot of OLD school, out of date info out there, as well as some total mis-truths. Maybe I can help the masses to under stand what is what.. The camshaft has to be strong enough to hold up to the wear and tear of performance spring pressures, the aggressive ramp angles, the rockers rolling on the lobe. PLUS get some good wear out of it!! Camshaft grinds ( spec ) is all important, and having a great powerful camshaft will sux if the cam wears out or even breaks!! Yes?? THUS a lot of cam grinders here in the US are reluctant to cut some of the camshaft cores that are on the market today from India/ Turkey.. ect. The quality of the cores wont meet the requirements of the camshaft grinder, and they WONT put out what they feel is NOT a good quality!! ( LOL good ole USA!!) 1) CORES: There are a bunch !! Cold cast has three different types. according to hardness and casting imperfections. It is cake to tell the difference with just looking at them! No trick here.. just look at what is coming out and what is going in the engine. Then there is the Billet camshaft cores. They cost at least 2 xs as much as the Cast cores. Their quality is 2 xs better as well.. They have a smooth polished looking core. No ruff casting marks. 2) The hardness of the camshaft differs from running the flat tappet core as the lifters are dragged across , or ROLLER Lifters as on ours that roll. The spring pressures of the OHC cylinder head isnt as stiff as the older push rod engines ( like the V8). Also the hardness is either re applied on the Cast cam.. or the billet cam is hard enough thru the entire core. Jut a note here.. The US uses different standards for harness than most of the rest of the world. 3) Head restrictions. Yep we all know about that spark plug tube on the exhaust side of the camshaft. Cant get too much lift unless you ding that tube.... and then IF you ding it too much, then you can not get the tool in to remove the spark plug. ( example looking at the schrick..) As we continue... just regular talk thats gonna be so everyone can evaluate the meaning here... cool?? I am sure there will be a lot of adding and changing the discussion points.. thats cool. First: Is a crappy quality of the core isnt important with the OHC engine we have?? I used to say YES!! Then all of a sudden there were a bazillion on the market!! SO I held my thought and decided there isnt the need for a 200.00 billet core, if these 50.00 cores are making it fine. Well as time goes by, we hear of bent cams, casting so bad it is scary, and actual lobes wearing off or the core breaking.. HMMmm... maybe I am rethinking?? Yes?? WTF.. how do we get a quality core at a price that all can afford ?? Easy!! Back in the day, they used to "REGRIND" camshafts.. and what happened?? a FEW ( that is a FEW) that didnt get the correct hardness would wash out the lobes!! Was that all do to the harness?? Or to aggressive of spring pressures, or the lack of correct lube and break ins.. ?? ALSO , MOST of the failures are the flat tappit type lifter camshaft, NOT a roller!! Sure is easier for a roller to ROLL than a tappet to be dragged, yes?? SOooo... we go back to the cores.. IF you start with a good core, the regrind ( to a POINT.. there is always a point!! LOL) will hold up and meet all the requirements of the intended use!! Now you can use the BMW OEM great camshaft core and cut a different spec on it!! AND Now the cost is just the R&D for the spec and performance, no core cost. This will work up to a certain spec.. really high lifts, or long duration cams need to have a larger core to grind, than the short lift OEM. Now back comes in the cost of the cores... HMMmmm... well what abot the old school way of cutting off the base circle to increase the lift and duration of a camshaft?? OMG!! That is BAD!! You can NOT do that!! But actually you can with our rocker and lifter parameters. The are hydraulic lifters.. they move around, they will accept a good amount of a smaller base circle with NO ISSUES!! LOL NFW!! Yep.. it is true!! View attachment 39965 Do to the limitations on the Head, EVERY camshaft I have tested that has a high lift Exhaust or a large duration.... Cuts the base circle!! The Schrick keeps the OEM base and there for needs to clearance the spark plug tube!! I would say it is a safe bet that ANY camshaft out there, that has a more aggressive number over the Schrick.... has the base circle smaller than the OEM!! Just has to be.. do your own measure and see!! This is NO biggy as it is made out to be on the web!! SOOoo... the 'under cut base circle" is more of a norm, than an exception!! I have hit a few BIG items!! ALL this is easy to check with just a visual..or a dial indicator ( or outside mic). This is NOT rocket science( lol)the specs can be guarded, but the way they are cut on the camshaft is the same as it has been in 100 years!! Hope this helps a few people. Just me................................................ ... Thumper