BritishV8 Forum

zzzzzzzzzzzzzzzzzzzz I'm so tired of this

After 5k miles


Now at piper cams,to be sorted out,and micro polished and re-hardened.
TA roller cam, not as good as they and everyone thinks !

Interesting. What are your lift, duration and spring pressures on that cam? What did TA have to say about it? Seems like information that we need to know.

Also if you don't mind my asking, was that the only lobe affected, and what was the condition of the matching lifter? (was it flat spotted?)

Jim

TA denied everything, lifters cam,springs everything bought from TA
Lifters are really good,couldn't find anything wrong with them


I can't remember spring pressures, but I had to buy a bigger set from summit !

My engine is being refreshed at an engine builders, he found the cam,

Cam not properly hardened?

Well, it's a lot of lift and about twice the valve lash that I'd expect to see, maybe more. That can't be helping.  What is most obvious to me from that photo is the appearance of the metal being displaced, mashed, or smeared, indicating ductility, or insufficient hardness for the operating conditions. A Rockwell hardness test of the lobe surface might have given you grounds for a claim against TA or it might not. This can't be good publicity either way. However, as close to the limitations of the system as you are running, only a small increase in spring pressure might do it, especially with the hammering caused by the large valve lash. You might want to double check to make sure your spring pressures aren't too high and then close up that clearance some. Considering where the damaged area begins that's what I would look at first.

Also, I realize that lash spec is probably from TA, but it really looks like a mistake to me.

Jim

Your using  TA heads ?  What king of rpm ?  Solid stainless valves ?  Big roller cams sometimes benefit from "glass beading the lobes, to prevent "skipping".  .650" is a mother-load of lift. Shure you need that much ?  All  8620 billet roller cams "should be case hardened to about .080".   Art.

Yes TA heads, standard valves the heads came with

Particles blahblahblah
http://www.shopfiltermag.com/choose-your-filtermag/

I'm going with that cam was destined to fail from the start.  Thats crazy lift and that lash is too big.  The rover cam is a small diameter cam.  The LS cams went with a huge diameter and thats what allows them to get .600 and greater lift and still maintain reliability.  No way I would go above .550 unless it was race engine and I planned on tearing it down frequently.  Seriously, how much extra hp was gained going with that much more lift, and did you really need that extra couple of ponies?

To be fair about it, Buick engines have been running up to .750" of lift. Mostly those are purely drag engines but that by itself doesn't explain the failure. Neither does "particles". If you look closely it is clear that the metal was not worn off the lobe, it was displaced. Now that being the case it is not obvious that the lobe would have failed even though it seems likely.

Jim

Ha!
Particles was too oblique.
Was thinking of the particles that are now running around inside the engine, that may go through a standard filter but the Filtermag will capture them.

Wonder whether the cam was bedded in at first startup... 2,000rpm for 30 mins, no stops for adjustment or tinkering.. Yes, some may think that elementary but I don't know whether it's a universally accepted practice.

Ivor

To further cloud the waters, Early lifters from TA were made by Morel. Those have fallen into disfavor and the supplier is now Johnson. The Morel lifters were blamed for a number of failures.

Jim


Morel lifters

Ivor,

"Wonder whether the cam was bedded in at first startup... 2,000rpm for 30 mins, no stops for adjustment or tinkering.. Yes, some may think that elementary but I don't know whether it's a universally accepted practice. "

Yes, for flat tappet cams.  Is that really a concern for roller cams?

The engine was "run in" on a dyno,
The cams back,
It looks like TA  sold me the wrong springs !
Stay tuned 😎

Bryan, could you let us know what the spring specs were (open and seated pressures)? Might help someone else avoid this.

Jim

you'll find a unicorn and talking frog long before TA ever warranties any kind of cam issue even when it's plainly their fault.

To be fair, proving it was actually their fault is a stiff challenge to begin with, especially in an engine built for racing where the builder is pushing all the limits to get maximum power. Probably not a fight worth starting.

Jim

The springs are 175psi at install height

Yeah that's getting up there a ways. Can you tell us what they were at full lift?

Jim

As soon as I find out, I will post on here

Get the cam , problem lobe(s), Rockwell "c" hardness tested ! Stop guessing.  Should be 56-58c +/-. No need to bed-in a roller cam.

Full lift, the springs are 465lb. !
The cam is back,  like new and freshly hardened.
More bad news ,on inspection one of the top hat liners had "slipped" down, . It couldn't have been done properly in the first place.
This was a brand new block, I had top hatted. Liner being done,and new cam bearings,
We're going to source springs around 300lb

Can I ask who did the top-hat as I'm looking to get this done - and would like to know who I should maybe scratch from the list... Email if you'd prefer....

I'm in the UK,
It was a firm called DJE, now long gone