Fretting over lifters, replace or not?

[ronstory]

For the 'puzzle' build (a bought a partially rebuilt engine, think short block), I'm concerned about putting in my new MMI lifter with the existing cam. I know in auto-mobile space the cam and lifters are replaced at the same time since the develop a wear pattern.

When disassembling the engine, i pulled the lifters in sequence and labeled them, but this was an engine that reassembled by a non A4 expert. Eg. piston arrows were point to the flywheel, half the connecting rods were correctly oriented toward the camshaft. So while I pulled them in order, I'm sure the previous owner did.

What is the risk of flattening the lobe an existing cam with new lifters? Should I add the compcams break-in additive?

Other wisdom or thoughts? If I could buy a new cam, this would be a no-brainer.

[Al Schober]

My only concern is that there's a slight hollow worn into the face of your lifters. I'd put a piece of 400 grit onto a flat and check the face of your lifters. See if it's an issue or non-issue.

[ronstory]

Happy to do that, any thoughts on just using the new lifters with good dab of assembly lube on them?

I would prefer to use the new ones, but concerned about cam being already having a wear developed a wear surface with the old lifters. ... and cam is inconveniently located if I have a problem with flat lobe in 30-50 hours of usage.

Am I just being paranoid?

[ndutton]

Lifters affecting the cam or the other way around?
http://www.moyermarineforum.com/foru...8&postcount=47

[ronstory]

Neil--

My experience as well, a cam and lifters are a matched set once they are ran.

So I can by new lifters from MMI but all the cams are used... so thus my quandary. However, the spring pressure on the A4 is pretty wimpy compared to the GMs and Ford i've rebuilt, it that the reason we can use new lifters with and "well established" camshaft?

[ndutton]

Originally Posted by ronstory

. . . . is that the reason we can use new lifters with and "well established" camshaft?

The answer is beyond my pay grade so my suggestion is to follow MMI's advice. If they are using new lifters with experienced cams, that should be reason enough.

[Dave Neptune]

The accepted rule for the cam and lifters being a package is a very good one. However it also has a lot to do with how hard the valvetrain has to work. In an overhead engine that reaches far more RPM's two things are needed spring pressure and lift. The springs need to be strong enough to follow the cam back down without loosing contact or valve float.

Now in these ole flatheads the same rule applies but not as much. I have resurfaced many lifters from flatheads and reassembled without issue. The surface areas of the overheads and the flatheads are about the same in both. The flathead especially the A-4 has very little lift, very gentle ramps and very little spring pressure. I just helped finish up a restore from the frame up of an old army truck with a White engine. No lifters available so we just flattened the end and put back in. Never really pulled one back down after this and never really needed to. This is certainly not the best way but on old slow turning flatheads it doesn't seem to hurt. Done this probably with a dozen or so engines.

We have used a few different set ups and this works. Find a drill press with a large enough chuck to hold the lifter and use a fine diamond knife sharpening stone. Use some light oil or just plain dishsoap and water. Bring the lifter down gently against the diamond hone and hold a light pressure against it while constantly moving the stone to facilitate flatness and not just a wear "spot". You can finish up with some 600 grit or finer sandpaper on a flat hard surface. The drill press or mill will maintain keeping the lifter flat and "square" or 90* off the axis of motion.

No fears of this on one of these A-4's but new on new is always best. I have had more than a few cams go flat but never in a standard flathead.

Also the oils today are so far superior to what was available I wouldn't worry unless the cam looked really bad, can't fix that without a regrind.

Dave Neptune

[Ball Racing]

My cam and lifters had rust damage from a hurricane flood into a garage where the freshly rebuilt motor was on the floor.
Anyway, I took each lifter and hand lapped it on a diamond stone.
They have held up great at max high rpm for this motor.
The problem comes more when the cam wears, losing its ability to spin the lifter, and wearing a groove into the lifters bottom.
Most cams are ground have a very, very minute amount of angle I mean small amount. Or if the lobe is ground on shaft aligned slightly away from the lifter center line. It keeps the lifter spinning.
If you surface a used lifter, the "abrasion marks" will hold a little extra oil on the lifter, the cam lobe and lifter should mate back in no problem.