With the increasing number of failures of flat tappet lifters in recent times, roller lifter camshafts would perhaps insure a given amount of durability in this area depending upon the roller lifter design.

Gerry, You're correct in that the Y has no oil feed to the lifters but that's only an issue if trying to run some form of hydraulic lifter.  Roller lifters refers to having a roller wheel at the camshaft side of the lifter which reduces the friction at the point of contact while also allowing for a much more aggressive camshaft profile.  On my Fe's, I block the oil galley that feeds the lifters when running either flat tappet solid lifters or non-hydraulic roller lifters.

1.) the lifter bore is round and has no provision to keep the roller aligned with the cam, what would need to be done, we wouldn't want the roller turning sideways on the cam. in order to place keepers on pairs of lifters the lifter would need to be much taller to stick out of the block and require shortened push rods.

2.) The lifters turning rotate the push rods, with rollers they would not turn, would this accellerate wear and require more frequent valve adjustment or would they wear less and require less adjustment.

Just some thoughts to stir more minds

Link bars as pictured above is one way of keeping the lifters from rotating.  Another method is a stud or protrusion in the lifter bore with an appropriately grooved lifter.  The SBF and scrubs use the 'dog bone' method with a 'spider' to keep the dog bones in place.

The pushrods not rotating on a street engine doesn't seem to be an issue for the factory equipped hyraulic roller cammed engines.  I'm sure a hardened pushrod tip and the appropriate hardness in the rocker arm would help though.

It would be great to have hyd lifters for the Y.. Surley someone can drill the block, if your going to go as far as bore the lifter guides.. Just a thought..

Hey Ted, didn't see ya at the Bracket Finals at Texas Motorplex this last weekend.. There was a Red 57 Bird, turning 9.1 ET..

Then what happens of you loose a roller, it appears to me you would be adding another weak link unless the lifter bores were drilled large enough to accomodate a larger roller.

Just my 2 cents

Unfortunately the standard run of the mill Y blocks do not have enough material to be safely bored for the larger and already available lifter sizes.  Ford did make a run of large bore hydraulic lifter blocks for the military but these are rarer than hens teeth.  It would be ideal to have the larger roller wheel on the lifter but it's not a show stopper as long as the lifter is built to superior specifications in regards to the axle and the support bearings within the roller itself.  Tolerances just get more critical with the smaller sizes involved.  The motorcycle industry is already there in that regard.

Ideally the camshaft does need to be steel but I have run specially ground 'cast' camshafts with roller lifters without any adverse effects on race engines but I was limiting valve spring seat pressures to 160-175 lbs and over the nose pressures to 425 lbs.  A street engine could get by on less but the weight of the lifter will help to dictate what the valve spring pressures will ultimately be depending upon the usage and application.  Regardless, camshafts are unique for roller lifters in that the lobes are without the bevel that's required to rotate the lifter on a flat tappet design and if trying to capitalize on the benefits that a roller lifter provides, then the ramp or profile is going to be much more aggressive on a roller camshaft than the run of the mill camshafts that are currently available for the Y.

True on losing a roller and the increased chances for some sort of failure in this area.  That comes with the added complexity and more moving parts.  Roller speed would definitely be higher with a smaller diameter roller and with it, the potential for increased wear.  Maintenance or replacement schedule would likely have to be stepped up especially if being run on a street engine.  But, with the OEM's getting 200K+ miles on roller lifters without failures attributed to the roller itself, the matallurgy and tolerances are available.  Failed or damaged roller lifters in a racing engine isn't necessarily attributed to the length of time that they've been run but rather the weakening of valve spring pressures to the point that the roller lifter is allowed to bounce or not stay securely seated on the lobe which then hammers and destroys the axle or bearings within the roller wheel.  I've even seen the wheels split in half as a result.

As far as pushrod lengths being shorter, that's typically not a problem unless there's some angularity problems that must be dealt with at the bottom of the head.  I typically have to alter pushrod lengths anyhow when correcting the valve train geometry so using non-stock length pushrods is not an issue from my standpoint.  I am using some of the 'retro' hydraulic roller lifters that are available for the older engines and some of these are so tall that they can not be removed from the lifter bores without first pulling the heads.  I would rather be able to pull the lifters without pulling the head but that's something that goes with the territory depending upon the engine.