Max Valve Spring Pressure for Reground Camshaft

[mopowers]

For those of you with reground hydraulic roller cams on stock cast cores, what kind of spring pressures are you running - seat/open?

I'm considering having a stock roller LA cam core reground to 233/241, .544" w/ 1.6s. but was told not to go much more than 110lbs seat and 300lbs open for spring pressure because of the cast core. Doesn't that seem light for a hydraulic roller cam with those specs. It's a just a street motor and won't see crazy RPMs, so maybe it'll be fine.

 

[RustyRatRod]

Whatever your cam grinder says. There's really no difference between a new one or a regrind regarding that.

 

[GTX JOHN]

I have run as much as 140 on the seat on my street cars with
no issues for a number of years with a quality CWC cast iron
cam. I never use the new Chinese cams in anything. I would rather
regrind the cam when there is enough left on the lobe to do so.

However, I never let the cars sit idling for more than a minute or
two without shutting the engine down in any of my cars.

 

[Bewy]

Flat tappet core are 'cast' & they can handle much more than that. It is the barrel diameter, the section between the lobes, that takes the load [ & flexes if not big enough ].

 

[mopowers]

Whatever your cam grinder says. There's really no difference between a new one or a regrind regarding that.

That's what I thought too. The cam grinder said that original cores weren't made from the best materials though and that the springs he recommends are seemingly nothing more than a comp 901. That seems a pretty strange for the hyd roller I'm looking at considering all other cam makers are calling for something in the 120/355 range for similar grinds.

 

[RustyRatRod]

That's what I thought too. The cam grinder said that original cores weren't made from the best materials though and that the springs he recommends are seemingly nothing more than a comp 901. That seems a pretty strange for the hyd roller I'm looking at considering all other cam makers are calling for something in the 120/355 range for similar grinds.

Ken Heard at Oregon says the stock Chrysler cores were hardened almost slam to the center of the core. He said they have never ground through the hardness. I guess if you're getting into solid roller territory, it's best to go with a billet core anyway.

 

[mopowers]

Ken Heard at Oregon says the stock Chrysler cores were hardened almost slam to the center of the core. He said they have never ground through the hardness. I guess if you're getting into solid roller territory, it's best to go with a billet core anyway.

That's weird. He told me that regrind I wanted would definitely grind through any hardening, but since it's mostly on the base circle where spring pressure is lightest, it's not a huge problem. He also said the material itself is such that he wouldn't recommend running much more than 110 seat and 300 open pressures. Seems a light for a small hyd roller, but I guess we'll see.

 

[RustyRatRod]

That's weird. He told me that regrind I wanted would definitely grind through any hardening, but since it's mostly on the base circle where spring pressure is lightest, it's not a huge problem. He also said the material itself is such that he wouldn't recommend running much more than 110 seat and 300 open pressures. Seems a light for a small hyd roller, but I guess we'll see.

What kinda cam are we talkin about here? Roller? All I've ever discussed with him are slant 6 and early Hemi cores. Plus he also said that of other Chrysler V8 flat tappet cams.

 

[GTX JOHN]

If the cams are stamped "CWC" they are the quality
casting and you will have no issues except with some
of the cheap Chinese lifters that will be an issue = not the casting.

The old CWC castings are not getting any easier to find.

 

[mopowers]

What kinda cam are we talkin about here? Roller? All I've ever discussed with him are slant 6 and early Hemi cores. Plus he also said that of other Chrysler V8 flat tappet cams.

Yep, hydraulic roller. Maybe they don't have as deep of hardening because they use a roller tappet. Who knows?

If the cams are stamped "CWC" they are the quality
casting and you will have no issues except with some
of the cheap Chinese lifters that will be an issue = not the casting.

The old CWC castings are not getting any easier to find.

That's good to know. Definitely no CWC stamped on mine. I only saw an "8" lightly stamped on the back end and a few three digit numbers cast between a couple lobes. Thanks for the info.

 

[RustyRatRod]

Yep, hydraulic roller. Maybe they don't have as deep of hardening because they use a roller tappet. Who knows?


That's good to know. Definitely no CWC stamped on mine. I only saw an "8" lightly stamped on the back end and a few three digit numbers cast between a couple lobes. Thanks for the info.

That's possible. It's also true that rollers require higher sprAng pressures and that puts more leverage against the cam core, so the need for something "other" than a cast core comes into play.

 

[GTX JOHN]

In our race cars we generally have over 200 on the seat and over 400 open with
no ill effects over the years. We run a LS style spring (Bee Hive).

Our street stuff is generally 140 on the seat and 350 plus open and some of our
engines are 10 years of use.

We have been using Clay Smith Camshafts for well over 50 years and George know
what is required in profile/taper/finish to make them live.

 

[lead69]

That's weird. He told me that regrind I wanted would definitely grind through any hardening, but since it's mostly on the base circle where spring pressure is lightest, it's not a huge problem. He also said the material itself is such that he wouldn't recommend running much more than 110 seat and 300 open pressures. Seems a light for a small hyd roller, but I guess we'll see.

Is this a factory magnum cam core?, I know Ken has had issues in the past with them being soft. they were having issues with the lobes failing during the regrind process and when they tried to weld them up they were like butter. This was a few years ago but that may be what he is referring to.

 

[RustyRatRod]

Is this a factory magnum cam core?, I know Ken has had issues in the past with them being soft. they were having issues with the lobes failing during the regrind process and when they tried to weld them up they were like butter. This was a few years ago but that may be what he is referring to.

That's probably why he's never mentioned this to me. I'm too broke to do a roller. lol

 

[mopowers]

Is this a factory magnum cam core?, I know Ken has had issues in the past with them being soft. they were having issues with the lobes failing during the regrind process and when they tried to weld them up they were like butter. This was a few years ago but that may be what he is referring to.

Thank you. Yes, I was looking into having a factory roller LA cam reground. What you posted would explain his hesitation to normal roller valve spring pressures. I made a couple more calls today and will most likely go with a new cam based on what I found out.

What I'm looking for seems to be too much for a regrind on a stock core. Heck, the guy from Bullet that I talked to recommended going no more than an additional 10-15* more .050" duration than stock on a regrind. He pretty much echoed what Ken at Oregon told me in that the flame hardening on the factory cams is pretty shallow. Add to that the spring pressures needed, and it's not the best recipe for success.

 

[lead69]

Thank you. Yes, I was looking into having a factory roller LA cam reground. What you posted would explain his hesitation to normal roller valve spring pressures. I made a couple more calls today and will most likely go with a new cam based on what I found out.

What I'm looking for seems to be too much for a regrind on a stock core. Heck, the guy from Bullet that I talked to recommended going no more than an additional 10-15* more .050" duration than stock on a regrind. He pretty much echoed what Ken at Oregon told me in that the flame hardening on the factory cams is pretty shallow. Add to that the spring pressures needed, and it's not the best recipe for success.

I was lucky and had a factory billet core from a mid/late 80s 318, if you can find one they are a nice piece.