Quality Flat Tappet Components

[Walter R. Malik]

So question is, has the cam/lifter industry found a happy mean and grinding most of the lobes to the same taper and the lifters to a matching radius?

That's a good question, but I don't know the answer.
I don't really get into those older, less popular engines.
Almost all the lifters I sell, are one of these part#'s: 817, 900, 992, 998, 2000, or 2011.
I really haven't studied the other lifters.
Next time I talk to the Hylift Johnson engineer, I will ask him about the crowns.

I used to use the A-969R with every hydraulic GM engine except Pontiacs and they worked fine. The pushrod button was a little shorter on the A-817 but, in Chevys, that didn't seem to matter; Mercury Marine also used the A-969's.
I don't know if Hylift Johnson even manufactures those lifters anymore.

[Mummert]

I never got a answer to my earlier question, of what should the difference in hardness be, between the lifter and lobe, if any.

When we started making our own "Flat Follower" cams for IndyCar, in the 90's, I talked with a few metallurgists, and the consensus was, you should have a difference of 4 points of hardness, on the RC scale. On those, the followers were 4 points less then the cams, and the followers would wear quicker then the cams. Later on, we had the followers DLC coated, and that solved the wear issues.
In the 2000's, we were making all the cams for the Indy Pro Series, and we made the cams about 8 points harder then the followers they were using. They were bucket type followers with a puck on the top of the follower. Those pucks would wear, and have to be replaced every season, but they were only about $8.00 each, so it was much cheaper and easier to replace them, then it would be to replace the 4 cams.

3-4 point of hardness seems like what I've heard over the years. Cast iron flat tappet lifters seem like they are harder than camshafts.

Mike do you know what outfit (CMC or Engine power) makes the Y block core and what grade of core it is.

[c1500sbc]

I will put my two cents in here.

For what is worth over the past three years I tried breaking in three flat tappet cams. One from comp, one from lunati and the most recent was a GM performance directly from the dealer and GM performance lifters directly from the dealer.

Breaking in the comp cam and the lunati cam went very smoothly as far as process goes. Assembly paste used, break in oil used, I measured the lifter bores, ran for 20-25 minutes varying RPM yada yada. Neither one of them made it. The comp cam made it through the break in, but failed a few miles down the road. The lunati cam did not make it throught the break-in.

The GM performance cam/lifter break in did not go so smooth. Same process, assembly paste, break in oil yada yada, but the passenger side exhaust manifold was leaking terribly. Had to shut it down to fix that so I didn't piss off any neighbors. Then the passenger valve cover was puking oil. Had to shut it down again to fix that. Then the cooling system had a bubble. Had to shut it down to fix that. BUT the cam broke in fine, runs fine, ive put about a 1000 miles on it and it's been fine.

[BCjohnny]

The Powell Machine video is interesting, and in line with what I've measured myself, cams around 50+ Rockwell and lifters usually 4-6 points higher ....... ultimate hardness all being equal would mostly govern component lifespan

I remember testing lifter faces years ago and anything under 61Rc was not used in our own engines.
Later ... flat lifters used to come in the tray with that little testing dot in the face.

Did you by any chance measure the cams as well, Walter ?

Would have been interesting to know the hardness differential between the two

[Edit : In the posts made I'm specifically referencing tapered lobe, radius foot lifters as you'd fine, in say, a pushrod V8]

[Walter R. Malik]

I remember testing lifter faces years ago and anything under 61Rc was not used in our own engines.
Later ... flat lifters used to come in the tray with that little testing dot in the face.

Did you by any chance measure the cams as well, Walter ?

No ...

[Walter R. Malik]

Lifter crown checking and Rockwell testing etc., what are some specs that would be a good starting point. 56-58rc hardness?

Dual Pattern cams take more time because you have to switch masters etc.

Thanks

Years ago, (maybe it is still done in places), we would buy a tray of lifters where every one had a small dot on the face which meant they were hardness checked to 60C Rockwell, minimum.
At a cam grinder where I worked 50 years ago, single pattern cams were usually more intensive as the master was sometimes flipped for intake and exhaust where a dual pattern cam simply had two masters mounted on the machine.

Things sure have changed a lot since then.

[Mummert]

Bump

[PRH]

pics I rec’d last week.

Cam was broken in with the inners removed, and actual break in oil.
Owner was seeing some very minor lash increases(.001-.002) on a couple lobes at 100-ish mile intervals.

Several of the lobes have pitting, this is about the worst one.
About 500 miles on it.

The nose of the second one isn’t as bad, but I don’t love the chatter on the flank.

BFA239F3-003A-471A-B306-A473C3FE416D.jpeg

[CamKing]

pics I rec’d last week.

Cam was broken in with the inners removed, and actual break in oil.
Owner was seeing some very minor lash increases(.001-.002) on a couple lobes at 100-ish mile intervals.

Several of the lobes have pitting, this is about the worst one.
About 500 miles on it.

The nose of the second one isn’t as bad, but I don’t love the chatter on the flank.
BFA239F3-003A-471A-B306-A473C3FE416D.jpeg

It doesn't look like it was parcorized, and the chatter is really bad.

[PRH]

A couple more:

E7E9CC3B-C095-4256-BBD2-4F7AE531C734.png

8425DDE4-340C-4105-B487-C0A8B6025936.png

I haven’t seen any pics of the lifters yet.

I’ve seen similar pitting(and much worse) on the nose in the past, but those were cams that had been running Schubek or tool steel lifters.
On those, the only part of the lobes showing any distress was right over the nose.
The severely pitted lobes on those cams were also noticeably squared off.
Lifters and base circles were mint, so no lash changes were observed.
In fact, the owners were unaware of any problems at all until engines were being serviced for freshening.