The decision between a roller cam and a flat tappet cam should be based on performance criteria and not upon the fear of premature flat tappet camshaft wear. There is always something amiss with any decision based on fear. Fear normally indicates something is not fully understood.
I do not think the fear of flat tappet cams failing prematurely should be a selling point for roller cams, this has the feeling to me of taking advantage of someone's fear and/or ignorance. For decades we used flat tappet cams without a worry. My Pantera's motor has one in it and operates trouble free. It is important to realize that even during this last decade most enthusiasts installed new flat tappet cams without a single problem, the wear problems occurred to a limited percentage of unfortunate enthusiasts. The problems occurred for one or two reasons, (1) the reduction of ZDDP in motor oil and (2) quality control issues in the heat treatment or surface finish of "off the shelf" cams and lifters. Armed with this information the solution to these problems is easy to determine, since off-the-shelf camshafts and lifters are suspect,don't purchase them off the shelf! Instead follow these steps:
(1) Purchase a camshaft directly from the cam grinder and request the cam grinder's best heat treatment and best surface finishing. Factory flat-tappet cams were phosphate coated for break-in. It would be advisable to have a cam phosphate coated if that option were available from your cam grinder.
(2) Request quality lifters that have had similar preparation during their manufacturing (Johnson or Eaton).
(3) Then use motor oil designed for racing (off-highway usage) which contains generous amounts of ZDDP (zinc & phosphorous). ZDDP has been reduced in motor oil because it "poisons" the catatlyst in catalytic converters and automobile manufacturers are required to guarantee their emissions systems for 100,000 miles. But racing engines (off highway only) are exempt from the need for catalytic converters, motor oil designed strictly for racing engines has a lot more ZDDP in it.
If we approach building the valve train this way, with a bit of engineering precaution, there is no need to fear the use of flat tappet cams, the cam & lifters should be damn near bullet-proof.
It is also important to point out that use of a roller cam does not give an enthusiast the freedom to use any motor oil in their motor. Distributor drive gears still need ZDDP even if a motor is equipped with roller lifters. Modern OHV motors can operate with modern "Low-ZDDP" oil not solely because they are equipped with roller lifters, but also because they have distributorless ignitions and crankshaft driven oil pumps.
-G
____________________________________________________________
Pantera Photos |
351C Historic Information |
351C Technical Information
If you use a 351C 4V powered vehicle for a grocery getter ... the eggs aren't going to make it home!
