Flat tappet lifters, wear patterns, cam lobe taper and other things. Let's swap opinions and ideas.

[padam]

It may be obvious to some but why do milder cams survive while the bigger cams seem more likely to fail?
Is it because the bigger cams have a greater stress between the cam lobes and lifter faces? Is it that the springs place more pressure on the lobes and lifters that make the oiling even more critical?
I remember the factory recall that Chevrolet had in the 70s or 80s about the failed camshafts in their 350 small block engines. That was supposed to be due to the grade of metal used in the parts.
I’ve seen videos where modern cams and lifters have been tested for hardness and compared to readings taken from original vintage parts. The numbers are either identical or similar so maybe the problems actually do lie elsewhere. Has anyone actually measured lobe taper before installing a cam? How about the crown of the lifters?
That “love him or hate him” uncle Tony had a video where he bought some lifters from an auto parts store and tested them for crown. The ones he didn’t like were returned for a refund. Some time later he went back to the store and bought lifters again and was given the same exact lifters he bought the first time… the store didn’t send them back to the manufacturer as defects, they just put them back on the shelf to sell to some unsuspecting customers!

I think Uncle Tony got all wound up in a knot on that issue however I did buy 8 spark plugs a couple months ago and 1 had obviously been installed and returned then resold

 

[toolmanmike]

I do think a lot of the new grinds with the agressive ramps probably crap faster and more often. If you grind a cam with an agressive lobe ramp, make it a roller.

 

[Kern Dog]

See, that plays to my curiosity.
Common sense tells me that there are limits to how sharp a cam lobe ramp can be with a flat tappet lifter. I’d love to know the failure rate of the fast rate of lift Setups.
On a somewhat related note, I have a cam in use now that is too big for my needs and am looking to go smaller. I liked the power of the MP 528 solid but would like a little more while still having adequate vacuum for power brakes. Do I have to switch to a roller to get there?

If this Lunati has been able to survive despite its rowdy nature, it encourages me that what I want can be found and also survive.
I run better oil exclusively now.

 

[gtxrt]

Not sure if I just got lucky .
My comp cam and lifters flat tappet, hydraulic is the XE 262H. 474 lift / 224 duration at 50.
Pretty mild compared to what most of you guys are running.
Comps instructions said to limit open spring pressure to 260lb.
I had purchased a set of crane springs # 99839 that pretty well mimic the mopar oem hp spring and damper. But at a crane advertised 280 lbs I used my old worn oem springs for the break in.

Used comps assembly lube, and Gibbs break in oil.
Timing was pre set and a known good carb primed.
I did a near 30min break in at a up and down rpm scale max aprox 2,500/ 2,800 rpm.
Few months later and a couple thousand miles I was swapping intakes so I got a good look .
View attachment 1749588

what is the seat pressure on the crane springs ?

 

[gtxrt]

I really believe that a good part of the problem is people. They want what a flat tappet cam was never designed to do. I blame a lot of this on Hugh's 904 lifter thing. You can't reliably push the limits with production parts . I'm one and done with the .904 lifter hype. A hydraulic tappet can't do what a solid does. A solid flat tappet can't do what a roller tappet does. Think before you buy into all the advertising/internet/magazine hype.

Hughes cams are not really that fast of a ramp advertise vs @.050 duration. they are putting too much lift vs duration in their cams causing problems. comp cams came out with some new hyd cams for Mopar. for solid lifters bullet ultradyne cams have some good ones. I have the small comp hyd in my Newport and a small solid bullet in my RT. very impressed with both.

 

[1967coronet]

what is the seat pressure on the crane springs ?

what is the seat pressure on the crane springs ?

90lb, I had to look them up again, Summit now lists them with a higher open rate of 340, not sure why the change. Same part number. It was near 4 years back I ordered mine.

 

[Kern Dog]

I really believe that a good part of the problem is people. They want what a flat tappet cam was never designed to do. I blame a lot of this on Hugh's 904 lifter thing. You can't reliably push the limits with production parts . I'm one and done with the .904 lifter hype. A hydraulic tappet can't do what a solid does. A solid flat tappet can't do what a roller tappet does. Think before you buy into all the advertising/internet/magazine hype.

Excellent points. There are limits as to what a flat tappet setup can do and I'd like to remain within those limits while making respectable power.
I'd run a solid FT again if I thought it might run a little quieter than what I have now. For the record, here is the cam cars for what I'm running:

I bought this cam on the advice of a FABO member that was trying to help me bleed off cylinder pressure to eliminate detonation. I've learned since then that is a poor shortcut that rarely works. The cam is way bigger than I need. I also have 1.6 ratio rocker arms so the lift is actually .576 intake and .600 exhaust before deducting for lash.

All you can do is try and stack the deck in your favor.
Don’t use the fastest lobes, only as much spring as you need, good high zinc oil, proper break in, and ……… hope for the best.

If you’re not feeling lucky…….. then it’s roller time.

I appreciate the time that you have taken speaking with me in the past. The words of yours that I quoted here are probably the best advice and wisdom that can be expected. There are no guarantees.
Today I tore down a 383 that a FBBO member gave me. I marked lifters and pushrods with a white crayon and had my friend Rich watch them as I spun the engine by hand with a long bar. I wanted to watch lifter rotation. After I had my first cam failure, I was told to make sure the lifters spun in their bores so I would test all the lifters in the engine but I never tried it with the cam in place and the engine rotating. It was wild to see the lifters stay almost still until the lobes started to rise, then the lifters would spin maybe 1/5 a turn, then stay almost still until the lobe ramped up again. I expected that with lobe taper that the rotation of the lifters would be linear and constant. The pushrods barely spun.

 

[Geoff 2]

I am not buying a lot of the reasons for FT cam failures. I have been using FT cams, & installing them, since the mid 70s. I NEVER had a failure until around 2001, when I had one fail. Brand name lifters that were soft.
[1] Cam companies do NOT make their own lifters, so no point in blaming Comp, Crane etc.
[2] Also, I do not buy the 'lifter bore alignment is out'. These engine blocks provided 000s of miles of trouble free service; bores do not suddenly go out of alignment in 2024, but were in alignment in 1995....

 

[Kern Dog]

I am not buying a lot of the reasons for FT cam failures. I have been using FT cams, & installing them, since the mid 70s. I NEVER had a failure until around 2001, when I had one fail. Brand name lifters that were soft.
[1] Cam companies do NOT make their own lifters, so no point in blaming Comp, Crane etc.
[2] Also, I do not buy the 'lifter bore alignment is out'. These engine blocks provided 000s of miles of trouble free service; bores do not suddenly go out of alignment in 2024, but were in alignment in 1995....

Thanks. Where would you think the fault lies aside from the one issue that you had in 2001?

In the case of my 440/495, it seems that if two cams of mine have lasted this long, the block itself isn't to blame.

 

[Geoff 2]

Well of course the oil gets/got a lot of blame...& I do not believe it was ever an oil problem. I believe it is the lifters: soft metal, poor/wrong radius on the base. Possibly a few poorly machined cams, but the same companies [ Comp, Crower, Isky ] etc are machining the so-called faulty cams.....& those same companies were not getting failures 25 yrs ago.

 

[Kern Dog]

I made mention awhile ago about the supposed pattern that a lobe and a lifter wear that match each other. That still isn't clear to me.
How could a lifter that rotates develop a unique pattern to it?
Who remembers Schubeck lifters? They went out of business awhile back but those had a ceramic like coating that allowed them to be used with no break in period and they had the ability to be swapped from lobe to lobe, cam to cam without failures. Why hasn't some company developed something like that? Not enough profit in that market?
Some of the videos I've seen discuss the taper to the lobes are supposed to be what...between 1 and 2 degrees?

 

[Mebsuta]

I just use the traditional lazy-lobe factory pattern cam and valve train. I installed the cam in a parking lot around 1990, and it lives to this day.

I didn't know anything then and still don't. I just assumed the people that designed this stuff knew what they were doing and copied them.

 

[Kern Dog]

Here are a few responses from a thread I started a few months back.

Only once in a car I helped out with. Lost 2 lobes off a 528 solid MP cam that was 25 years ago. Pulled the motor and went through it and there was ZERO damage to the bearings. After seeing that we should have just pulled the radiator and shoved a new one in as the filter caught it all.

This is familiar. ^^^^

Been building motors for almost 50 years. I use a small amount of break in lube on camshaft .My motors all get Zinc additive and a can of STP. The last ten motors Ive built I used NOS lifters from the 60s, 70s or 80s! Zero problems

NOS lifters get you original metal that was durable back then and just as good today. I'm still curious about reusing resurfaced used lifters pulled from "core" engines.

Always stock cams & lifters with zero ptoblems

Same here. Mild camshafts seem to last and last but I want to go fast.

 

[padam]

I think that it is a combination of all of the factors discussed.

Think about how simple the flat tappet system is. But it is still metal on metal under pressure. (I know there’s a film of lube. ) It worked well for millions of cycles in factory form.

If you were designing a system today is that how you would do it?

I remember reading the DC manuals back in the 80s and them saying.600 lift was really getting radical. Not too radical these days.

I can relate it to this situation. When I raced my car in the 80s and 90s I ran it similar to what I have now but with an 8-3/4 rear, sure grip Richmond 4.30 gears factory axles. I was running 8.20 1/8 mile times.

My buddies always told me I was going to blow up the rear end. I never did. Towards the end of my racing I did break a factory axle.

When I started racing again I rebuilt the engine in 2021, a little bigger cam, but mostly similar stuff. 50 maybe 75 more hp. A little heavier clutch. Brand new spool, axles, gears.

Now the tracks use a lot more traction compound.

2021 I broke the driveshaft, then blew up the rear end. After I put in the Dana next season I bent the wheel studs. All for going .5 seconds quicker in the 1/8 mile.

I was just on the edge of what I could get away with for all those earlier years. I think it’s the same with flat tappet cams. The system can only support so much.

 

[AR67GTX]

Don’t judge but I own an old Corvette so I frequent the C2 Corvette Forum and there was a recent discussion about the flat tappet issue. Besides crappy foreign steel, lack of proper surface treatment on cam lobes, poor crown and lobe slope on lifters/cams, one of the retired GM powertrain engineers commented that the problem is being aggravated by the increasingly higher and excessive spring pressures that cam companies and performance parts suppliers are recommending. And the hotter the cam you use the higher the spring pressures they recommend. In most cases they are far higher than GM ever used for their 6,000 to 6,500 mechanical lifter performance engines. One reason for the higher failure rates in the higher performance cams.

 

[oldbee]

Like AR67 related, maybe the lifter manufacturers need to upgrade what they do. High spring pressures have to be part of the problem (but they’re necessary).

 

[Kern Dog]

Don’t judge but I own an old Corvette so I frequent the C2 Corvette Forum and there was a recent discussion about the flat tappet issue. Besides crappy foreign steel, lack of proper surface treatment on cam lobes, poor crown and lobe slope on lifters/cams, one of the retired GM powertrain engineers commented that the problem is being aggravated by the increasingly higher and excessive spring pressures that cam companies and performance parts suppliers are recommending. And the hotter the cam you use the higher the spring pressures they recommend. In most cases they are far higher than GM ever used for their 6,000 to 6,500 mechanical lifter performance engines. One reason for the higher failure rates in the higher performance cams.

The springs putting all that pressure on the cam and lifters does make sense to me as a contributing factor. It seems plausible that as spring rates go up, reliability would go down.
I'm not looking to go 6500 rpms. The Tremec in the car doesn't like to shift once I'm over 6000 anyway. It would seem that using a cam that gives peak power below that would be better fort many reasons.

 

[PRHeads]

Mechanically quieter and smaller than the current cam……..
Put the old 509 back in.

 

[Kern Dog]

I gave that away about 10 years ago!
I did run it with stock rocker arms and then with these 1.6 arms. Back then I was fighting the detonation but since then, I am using dished pistons....

I remember way back "when", Mopar Performance had a 440 based 500" crate engine that used the '509 cam with 1.6 rocker arms to get to .543 lift. Theirs was just a tick over 9 to 1 compression but was rated something like 530-540 HP if I recall. It does have that drawback of low idle vacuum. Oddly, the '528 solid was great for that...The power was good and idle vacuum was excellent for the power brakes.
Back when I had the '509, I had detonation issues and struggled with the crappy MP electronic distributor too. It had a crappy advance curve that didn't know how to improve. I chased my tail for awhile. The car ran great up to 1/2 throttle but what fun is that?
I am in no way an expert now but I'm not as clueless as how I was then.
I've had help from guys on this forum with some of this stuff and am making fewer mistakes now.

 

[PRHeads]

Fortunately, the car isn’t currently broken, so there is no rush to make the swap.

Oddly, the '528 solid was great for that...The power was good and idle vacuum was excellent for the power brakes.

Not odd at all. The 528 has way less overlap than the 509.