what are your experiences with these rampy camshafts?
I have a few. Some good, some bad. I won't share a definite opinion, becuase those cams do have their place and application.
My first aftermarket cam ever was a VZ25, which from memory was .470" @ valve (stock 13-1600 1.1:1 rocker) and 286 seat duration, 256 @ .050". I originally purchased this cam (at 17 years old, mind you, succumbing to the "big numbers syndrome") for a 1914cc I was building on paper, though my bank account didn't follow along. In light of a teenager's economic plight, the 1914 became a 1641 but the cam stayed. Those that were around at the time 1988-89 (Sheep, not sure who else we hung out with here...) can confirm that motor was a real tiger. Say what you will about overcamming, but I can contest that with 40 x 35 valves, 9.0:1 and dual 36DRLA's this motor was able to hold its own from idle to 7000. Sure, it came into its own @ 4000 and above, but it was in no way "undriveable" (contrast: I ran Clay Smith 320 in 2332, 11.5:1, close gears, IDAs, etc... to me that was undriveable). It was driven daily, as a commuter, to and from college and work, neither which were nearby. After about 24 months, maybe a few less, I had killed 2 sets of springs, wore out a valve job, and widened the keeper grooves in all 8 valves. Now before you say "SEE? VZ cams do that, they wear shit out real fast!", realize these were off the shelf Claude's 044 Magnums that had just hit the scene, straight out of the box, with single springs, not shimmed, who knows how tightly the retainers fit keepers and springs, keepers were not ground, and God knows where the spring pressure was. So, running that motor as hard as I did, even a 110 would have killed parts off, setup as it was. Sure, the VZ just did it faster, I get that, but, that 1641 was untouchable among the VW guys I knew at the time, and even a few small block GM machines got to see my taillights a few times.
I got “numbers greedy” again in 1991, and stupidly, removed the W125 from my stone-reliable 2054 driver, and replaced it with VZ35, “the biggest cam I can buy without forking out dough for ratio rockers”. I ran that cam for precisely ONE week. It was horrible to drive in my car, with 44IDF and 7.8:1. See how stupid I was, running 278@ .050 with that CR? I can’t accurately explain how bad it really was to drive. Seriously, after a very frustrating road trip from SF Bay Area to Ventura CA, the car came home and had the motor yanked, and cams swapped back to W125.
Every motor I have built using the VZ15 has run very very well. At Buggy House, we built a 1914 daily driver (the guy had no other car) for a nice ’67 sedan, using that cam, 044’s and Weber 44IDF’s. The kid drove the wheels off of it, and it always ran hard, it was really more than the kid needed, and maybe could handle. The car had 165 radials on 912 steel wheels and it was a real handful in 1st and 2nd. The key to that cam is how fast it gets the valves open and keeps them open. Compare duration @ .050 and seat duration and look @ lift. Unfortunately, all that action, compressed into a “shorter” time, means things like lifters, pushrods, springs, valves, etc… all have to move farther in less crank degrees, i.e., time. With that said, I will leave you with this info…. My good friend John Holleran built a 1914, 8.25:1, VZ15, 044 CNC round ports (that he did some handwork on) and 46mm modded Kadron carbs, and made 139whp with it. This is in a fiberglass 356 speedster kit, which is daily driven, and as of today, nothing in valvetrain has budged. Canton filter comes clean every time.
Choose your “battles” wisely and prepare accordingly, and you can run a VZ, just make sure you have your ass covered, in the details.
The Cal-look Lounge
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