That being said what is the down side of a setup that reduces valvetrain wear and tear and also brings you into your power curve sooner and keeps you there longer. Now maybe I am and so are todays car manufactures are all wrong (because they're putting roller cams in todays engines) and we need to come consult your expect opinion on cams. .
There are several downsides. I am VERY aware of them because I spent about two months trying to get a roller cam for my /6 turbocharged race car.
I have a friend who, up until November, raced an (NHRA) A/SA big block 427 Chevy, a class in which OEM style lifters are a class requirement (flat tappets.) He experimented with roller, "billet" blanks (no billet blanks were available for flat tappet big block flat tappet Chevy cams), because he was flattening cams; He tried ceramic (Schubesk) lifters and tool-steel lifters, all the while adding ZDDP in required amounts to his cam/lifters. He ended up with no less that four (4) "flat" cams, and that scared me to death!
I started trying to buy a roller cam for our /6/turbo project, in deference to his ongoing problems.
I emailed or called every cam manufacturer I could find that ground roller cams and slant-6 cams over the last 25 years. I wanted a roller BAD.... real bad!!!
They all told me the same thing, in one way or another: There are
no blanks extant for a /6 roller cam. In order to get a roller cam ground, I'd have to first, provide the cam grinder with a blank ($1,000.00+) and then come up with a set of lifters that would work on that blank and come up with some way to keep those lifters aligned.
Special pushrods would be required to match the different required length, and one-off receiver cups would be required in the lifters.
As someone else pointed out, the oil pump and distributor would be a problem, since there is no gear on the cam to drive them,
We are looking at at least @1,500.00 here for a CAMSHAFT. Probably a whole lot more after procuring a remote drive oil pump and a distributorless ignition.
The amount of time necessary to get all this stuff together, and the insane cost to make it happen, would make it a
"never gonna happen" deal for 99-percent of people fooling with /6 cars.
Probably more like 100-percent.
I was disappointed in what I learned, but have since come to the realization that the reasons that other engines NEED roller cams and /6s don't are:
1. Slant 6s have small (light-weight) valves, so don't need a lot of valve spring pressure to control valve float, so cam life is not a problem, generally.
2. The 4,125" /6 stroke keeps RPM's on the most popular (225-inch) /6 motors under 6-grand, so a lot of valve spring pressure is not needed to control valve float.
3. There are no racing organizations that have classes for a /6 where a roller tappet would be a class advantage. NHRA only has classes for '6s in stock eliminator.
In short, common sense would tell you (or, anyone else) that at this stage of the game, dealing with the considerable hassle and egregious expense for the slight advantage afforded by a roller cam, in a /6 is just not something that a thinking person is going to do.
I once saw a guy put a Chevy V8 in a Nash Metropolitan (look it up) with a VERY LARGE shoehorn.....
Just because you CAN do something, doesn't mean you should.
