Spring pressure ratings for various cams and applications?

[RobinLBuddi]

Hey guys!

Can anyone tell me what is the general "rule of thumb" regarding recommended spring pressure ratings to use with different cam core alloys. In other words, where is the line drawn for this. I do realize that certain things such as lobe aggressiveness and lift height probably make a difference when trying to figure this in, but I'm just wondering what the "ball park" figures are on the max spring pressures to be used for the following cams:

For cast iron hyd flat tappet cams?
For cast iron hyd roller cams?
For 8620 billets steel hyd roller cams?
For solid roller cams?

Also, if anyone knows where I might find any good information specific to this subject, that would be very helpfull.


Please let me know, I would very much appreciate it.

Thanks a million!!!

Robin L. Buddi

 

[Ormand]

If you get a catalog, from Crane, or Competition Cams, or Crower, or any of those guys, it will have a guide as to what "kits" to use with what cams. They are all a little different, but any one will give you a general idea, which seems to be what you want. I guess this is for a Buick? The numbers will be different for different engines,too. Check for "on-line" catalogs, maybe you can just download what you need.

 

[RobinLBuddi]

Thanks for the response! I guess I should've explained myself a little bit better from the start. I have been looking for some information that is more geared towards the question of; What really determines when it is acceptable to use hyd. roller lifters on a cast iron hydraulic roller camshaft? If this is acceptable at all, with what valve spring pressures? From what I have gathered from several people, is that it should never happen, hyd roller lifters on cast iron will not work, however, I am trying to prepare for if I ever have to present my case in a high potential small claim suit. I'm looking for pertinent information on the subject. Even a written, signed statement from any individuals and/or buisinesses that are experienced and/or educated in the field, either an experienced professional engine builder, an experienced machinist, or metalurgist. The statement would only need to be in short, and addressing reason(s) as to why hydraulic roller lifters shouldn't be used on a cast iron camshaft, and maybe also add what has been known (from your perspective) to happen in the past when Comp Cams had tried this same combination of parts, which had resulted in countless camshaft failures (re: econo budget roller problems).
If anyone can possibly help me out with this, it'd be very much appreciated. Please let me know, either reply or private message me.

Thanks a million!!!
Robin

P.S. If anyone is confused by this post, please go here: http://www.turbobuick.com/forums/showthread.php?s=&threadid=71425&highlight=hyd+roller

 

[Ormand]

All cast iron is NOT the same. There are better grades of cast iron which would make an acceptable roller cam, although not likely a "premium" roller cam. (high lift) Some of the OEM cams are cast iron. The trick is to get a matched set from a cam grinder you can trust. But how you know which one to trust- that's a good trick, apparently. The cast cam will support lower lift, less aggressive opening/closing rates, like the OEM smog cams. For a high performance cam, the billet cams are more common. Tough to say what the break point is, if you read the Mondello cam thread, you may be scared away from cast iron.

 

[RobinLBuddi]

Yeah, but by running steel hydraulic roller lifters on a cast iron camshaft, no matter what the grade of iron, would be inevitable destruction, given that the steel roller lifters are much harder than the cast iron. Especially if stiffer springs were used, 140# closed, and 340# open max.

The specs for the camshaft in question here are as follows:

Mondellos' "RH-6-14" (which is an Engle cam):

Gross Cam Lift Duration @ .050

Intake = .319" .205"
Exaust = .325" .214"

Lobe centers = 110

Valve Lift: Running Duration:

In. = 510 254
Ex. = 520 266

VALVE SPRINGS (Comp Cams 986-16)

Closed = 120lbs. min. 140lbs. max.
Open = 290lbs. min. 340 lbs. max

Every lobe was wiped out on this camshaft, I'm pretty certain that it wouldn't have ever happened if Mondello would have sent me an 8620 Billet Steel cam, which is what I'd ordered, and what I'd paid for.

Thanks!
Robin

 

[Ormand]

I think the cast iron camshafts used by GM for roller lifters may be surface hardened. I know they're more expensive than the ones for flat tappets. Ductile cast iron can be as hard as 320, brinell, and have a tensile strength of up to 175,000 psi. So, like I said, it all depends... just have to trust the cam grinder/vendor.