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

[RemCharger]

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



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

That was my reasoning to go with the 528 about 20 yrs ago when I was using a .160 in the hole 440 for racing. If I recall it was 60° vs 76°, which was quite a bit

 

[4speed68rt]

I lost my first one recently in a small block chevy. It was just a mild rv cam and it flattened 14 of the 16 lobes within 10 minutes of break in on the break in stand. It was an enginetech brand and lifters too. The vendor told me that it was because I used Valvoline VR1 oil for break in. I tore it apart and put all new bearings and put in an Elgin cam and lifters, with Comp cams cam lube and Lucas break in oil and it broke in without a problem. I am not sure what to believe from the vendor, but now I am using the same stuff for my next install that I am doing now on my Big block Chevy. I hope it works again. I am like you Kerndog, I want to understand why it happened. Pi$$ed me off.

 

[HEMIB]

Talking to my engine builder he said he had 3 crane cams wiped in a week last month mentioned he always buys 20 lifters hardness tests them & normally 2 or 3 get rejected said he has not seen so many failures before

 

[Gunner1]

If you think about it. As the lobes became more aggressive the seat and over the nose pressures have increased. Most of the cams I’ve seen that were going flat all started on the nose. A cam with a 350# spring and a 1.5 rocker put 525# on a maybe .200 diameter contact patch. That is about .03 of a square inch. A .904 lifter has an area of about .7 of a square inch. I’m of a mind that the new oils are no longer formulated for our older motors. I try to run good old dinosaur oil at least 15/30 with a modern add in additive for older cars.

 

[Kern Dog]

I lost my first one recently in a small block chevy with a mild rv cam and it flattened 14 of the 16 lobes within 10 minutes of break in on the break in stand.

Wow, I've never wiped one out that fast.

The vendor told me that it was because I used Valvoline VR1 oil for break in. I am not sure what to believe from the vendor.
I am like you Kerndog, I want to understand why it happened. Pi$$ed me off.

In my experience, NO vendor or manufacturer is going to actually admit out loud that their product failed. They always say some lie like This is the first that I have heard of this...
Bullshit, man. You just ruined your credibility. In 2020 I called Racer Brown and talked with a guy about getting a flat tappet cam for the 383 in Jigsaw....

I told him of my concerns about failures and HE gave me that line.
Come on, man....if a guy like me has seen 3-4 failures in 18 years, a vendor sure has heard about it too. Denial of a known issue makes you look stupid or dishonest.
I know, I could just default to a roller and be done with it for awhile. I'm not afraid of spending the money if I could sell off a few things around here to make me feel better about it. Like many of you, I'm not poor but I have to rationalize the expense.
I'd want quieter operation, more vacuum for the power brakes, a power peak below 6200 rpms and more power than the '528 provided. FBBO Moderator @HawkRod has a hydraulic roller in his Road Runner and is quite happy with it.

I know that every engine and owner are different so what may be great for one may not be ideal for another.
I'm at 9.8 to 1 with these Edelbrock heads and quench/dished pistons. I've considered a switch to the Trick Flow heads at some point but I'm in no hurry there.

 

[Kern Dog]

How does one determine the overlap that a camshaft will have?

The first set of specs here is from one of the Comp Cams XE285HL that I had in 2006:

Here are the specs for the Lunati that I have in the engine now.

 

[Geoff 2]

To calculate overlap, you add the exh closing to the intake opening. For the Comp 35+37= 72*.

 

[Kern Dog]

That makes sense and I did notice that but why the heck did Lunati list their numbers above? This cam I'm running has to have more than 50 degrees of overlap for how rowdy it idles. What did they do wrong?

 

[gtxrt]

That makes sense and I did notice that but why the heck did Lunati list their numbers above? This cam I'm running has to have more than 50 degrees of overlap for how rowdy it idles. What did they do wrong?

the lunati cam has 100 degrees over lap using intake-exhaust. I get 71 for comp and 105 for lunati using advertise duration and LSA specs. must have to double the intake and exhaust valve opening and closing specs for the lunati

 

[HawkRod]

Late to the party here, but here is my 2 cents worth:

First, I will all but guarantee that there is no single reason why a new cam/ lifters fail. I'm sure if we knew the reasons for past failures there would be different reasons in different cases. Having said that, oil without zinc is a reason for failures maybe 10+ years ago, but now that issue is well understood so I think it is less common failure reason today.

I personally believe lifters not spinning in the lifter bores is one big reason. It only takes one bore with a burr in it to wipe a cam. And as these engines get older, and potentially sit awhile before they get rebuilt, that chance gets greater. I now use a small ball hone on the lifter bores and then make sure every single lifter and bore work smoothly.

I think another reason are the spring rates. "In the old days", we typically took a running engine and swapped in a "hot" cam and lifters to soup it up. How many of us changed springs? Most of us didn't, and yes, the engines started to float above 5000 RPM. But those weak springs helped save the cam at start up.

If I were building a flat tappet cammed engine, I would absolutely get lifters with an oiling hole or groove to give the cam direct oiling. Sure those lifters cost more, but how much does it cost to wipe a cam?

 

[PRHeads]

I was getting 71 for the Comp, using the adv duration and the lsa, which doesn’t agree with the open/close numbers(72).

Then I saw that the open close numbers are 1 deg off on int(286) and ex(298) from the adv duration numbers.

The Lunati is 105 based on the advertised(which is at some undisclosed lift point), and lsa.

Overlap numbers are usually based of advertised duration.
Keep in mind that comparing overlap between solid lifter and hydraulic lifter cams isn’t going to always be “apples to apples” because of the varying lash points of the solid cams vs the zero lash of the hydraulics.
The same holds true for solid cams that use different lash points and/or advertised duration lift points(the lift at which the adv duration numbers are measured).

 

[gtxrt]

the modern solid cams with a tighter lash like 16-18 thousand you can get close with taking 6 degrees off the duration at .050 so 226 hyd would be 220 at .050 on a solid cam. you need to add about 12 degrees to the advertised duration on a solid cam. so a 268 hyd would be close to a 280 advertised duration on a solid.

 

[Kern Dog]

Late to the party here, but here is my 2 cents worth:

First, I will all but guarantee that there is no single reason why a new cam/ lifters fail. I'm sure if we knew the reasons for past failures there would be different reasons in different cases. Having said that, oil without zinc is a reason for failures maybe 10+ years ago, but now that issue is well understood so I think it is less common failure reason today.

I'm not sure that I spelled it out but with those two Comp Cams that I ran in this engine, (2006) the lifters were from CC. I used regular oil but with the Comp Cams break in supplement during break in, then just regular oil afterward. I didn't know that the regular oil was a potential problem.

I personally believe lifters not spinning in the lifter bores is one big reason. It only takes one bore with a burr in it to wipe a cam. And as these engines get older, and potentially sit awhile before they get rebuilt, that chance gets greater. I now use a small ball hone on the lifter bores and then make sure every single lifter and bore work smoothly.

I don't know when I started checking for free movement of the lifters but it was likely after the 2006 failures.

I think another reason are the spring rates. "In the old days", we typically took a running engine and swapped in a "hot" cam and lifters to soup it up. How many of us changed springs? Most of us didn't, and yes, the engines started to float above 5000 RPM. But those weak springs helped save the cam at start up.

The 2006 failures were with the same springs that came in the Edelbrock heads.

If I were building a flat tappet cammed engine, I would absolutely get lifters with an oiling hole or groove to give the cam direct oiling. Sure those lifters cost more, but how much does it cost to wipe a cam?

I used the Johnson's EDM lifters with the '528 cam and this Lunati. The '528 was trouble free for many years but went bad fairly quickly after changing from Valvoline VR-1 to the synthetic that had high detergent.
I have not ruled out the use of a roller camshaft, I am just trying to understand what commonly goes wrong with these flat tappet setups.
That Comp Cam that HawkRod used is listed as Out Of Stock on the Comp Cams website.

 

[PRHeads]

That Comp Cam that HawkRod used is listed as Out Of Stock on the Comp Cams website.

In stock at Summit.

 

[gtxrt]

my last one I did on a fresh motor with a new comp cam the fastest the rings ever seated. 30 wt non detergent super tech oil with a bottle of Lucas break in additive. the next cam break in only no rings to seat am going to try the Lucas break in oil.

 

[Kern Dog]

In stock at Summit.

View attachment 1750426

After this, I’m interested in the cam but am unsure on the lifters. I’ve seen some videos on the “Evolution “ lifters but the comments below the video didn’t inspire confidence. The techs at CC never bothered to chime in.

 

[PRHeads]

You’re in the drivers seat.
There are plenty of cam grinders and lifter suppliers to choose from.

 

[PRHeads]

Don’t wanna spend the big bucks(and you’re feeling lucky)?
This cam works great with 1.6 rockers.

Not a Comp fan?
Oregon cam grinders has a version of that cam.
Howard’s has one very close as well.

 

[gtxrt]

comp has good hyd cams for mopars but I don't like comp solid cams for mopars. bullet has a solid with a lot more lift and less advertised duration for more vacuum smoother idle. 242-246 @50 with only 271-274 advertised duration 548-543 lift.

 

[Kern Dog]

I have these 1.6 rocker arms in the engine that sure do push the lift numbers up higher.

I don't know at what point the lift is too much but I'm at .600 exhaust now minus .014 lash. I'd have to consider that before committing to any choice. If I had to buy new rocker arms, that is yet another expense.