Roller lifters, Anyone tried them? Options

[r_towle]

Has anyone tried roller lifters in a type 4, or any flat motor?

[Jake Raby]

Those are .742 Harley lifters. The wheel diameter is so great that you must have a very large base circle camshaft. These hate lash, the issue that I had with them came mostly from axles failing prematurely do to base circle, and lash. The closest I came to success with these was using a Schubeck RollerX lifter that has no axle, but those went away with Schubeck in 2007.

If the base circle is too small, these things run super loud, sounds like a diesel. They beat themselves to death.

Again, you will have to rework the case to realign the cam tunnel with the lifter bores. These are no where near perpendicular enough for a roller cam to live without cam walk in any T4 case I have seen yet. That includes brand new, NOS cases. Call a company named BHJ, for about 6k they will make some jigs to your design to facilitate this, but when it doesn't work, and you chop up what they made to make it right, you'll be mad enough to spit nails.

You must "nest" the lifter with this arrangement, else the first rotation of the cam, every lifter will turn 90 degrees and crash the cam. We even tried to change the cam lobe to retain the proper lifter orientation, but those oil samples had 12X more iron in them than the worst comparative sample, and visual wear was very clear.

Modern Porsche engines have nested tappets, to allow for variocam plus on the intake, and VVT on the exhaust. In these engines a dowel is employed to do the job of alignment, but the cam profile is kept very conservative. It's no where near the lift per crank degree that the mildest roller profile that you'll find (Fox body Mustang, stock profile).

Don't put too much stock in what the guy in those pics has done... It's clear that he hasn't been able to achieve a proper cylinder head to cylinder seal, which is the first essential to T4 performance. See that nasty head surface? Yep, he had a head leak.

This post has been edited by Jake Raby: Oct 31 2015, 06:31 AM

[HAM Inc]

Those are .742 Harley lifters. The wheel diameter is so great that you must have a very large base circle camshaft. These hate lash, the issue that I had with them came mostly from axles failing prematurely do to base circle, and lash. The closest I came to success with these was using a Schubeck RollerX lifter that has no axle, but those went away with Schubeck in 2007.

If the base circle is too small, these things run super loud, sounds like a diesel. They beat themselves to death.

Again, you will have to rework the case to realign the cam tunnel with the lifter bores. These are no where near perpendicular enough for a roller cam to live without cam walk in any T4 case I have seen yet. That includes brand new, NOS cases. Call a company named BHJ, for about 6k they will make some jigs to your design to facilitate this, but when it doesn't work, and you chop up what they made to make it right, you'll be mad enough to spit nails.

You must "nest" the lifter with this arrangement, else the first rotation of the cam, every lifter will turn 90 degrees and crash the cam. We even tried to change the cam lobe to retain the proper lifter orientation, but those oil samples had 12X more iron in them than the worst comparative sample, and visual wear was very clear.

Modern Porsche engines have nested tappets, to allow for variocam plus on the intake, and VVT on the exhaust. In these engines a dowel is employed to do the job of alignment, but the cam profile is kept very conservative. It's no where near the lift per crank degree that the mildest roller profile that you'll find (Fox body Mustang, stock profile).

Don't put too much stock in what the guy in those pics has done... It's clear that he hasn't been able to achieve a proper cylinder head to cylinder seal, which is the first essential to T4 performance. See that nasty head surface? Yep, he had a head leak.

Holy head-leak Batman!

Those registers have been opened for big bore jugs, which I'd bet plenty of $$ were iron. Leaks in general, and that area in particular, are a classic symptom of big iron jugs, which just don't stay sealed long on T4 engines.

I have seen that soooo many times over the years I can spot it from across the room.