Crane Cams is BACK!!!

[Duke W.]

Re: Crane Cams is BACK!!!

Until the advent of beehive valve springs I would have agreed with you. Modern springs, such as those used with the LS series engines are an excellent choice for vintage engines. They will allow somewhat higher lift and somewhat faster ramp rates while providing valvetrain control impossible to achieve with old fashioned springs. They are lighter in weight, do not require inner springs, and do not require dampers.

The LS1 spring provides 114 pounds on the seat, a 313 lb/in rate, and 255 pounds over the nose at .450 lift. Compare this to the much heavier 068 spring with damper which delivers 80 pounds on the seat, a 267 lb/in rate, and 200 pounds over the nose at 0.450 lift. The old "Z28" spring (142) has 110 pounds on the seat, a 358 lb/in rate, and 271 pounds over the nose at 0.450 lift.

Check the numbers again. The LS springs have much greater force and rate than the 068 springs, but the LS valvetrain can handle it with OE reliability because it is stiffer and incorporates roller lifters.

The 068 springs have proven reliable in billions of acculumated SB miles in the last 35 years. With attention to proper installed height they will rev to 6500+ with an OE hydraulic lifter cam and 7000+ with an OE mechanical lifter cam.

Plus the Sealed Power VS77 equivalent costs about a buck a piece.

I go by the creed: If it works, don't fix it!

Duke

[Duke W.]

Re: Crane Cams is BACK!!!

I won't even read your pompous post through before replying.
There you go again, changing the subject in order to divert attention away from your error. You should have been a lawyer instead of a self proclaimed engineer.
The problem here is that everybody here is too afraid of you to pull back your curtain of smoke and mirrors. You remind me of the scene in The Wizard of Oz, when the wizard is exposed for the little man he is, after being discovered manipulating the controls of his apparition machine.

I endeavor to explain the complicated physics of IC engines to those who are interested, and you won't read my explanations in hot rod magazines. Granted, it's a rather complicated subject. With effort some may understand, but some will never get it.

Duke

[Joe C.]

Re: Crane Cams is BACK!!!

Check the numbers again. The LS springs have much greater force and rate than the 068 springs, but the LS valvetrain can handle it with OE reliability because it is stiffer and incorporates roller lifters.

The 068 springs have proven reliable in billions of acculumated SB miles in the last 35 years. With attention to proper installed height they will rev to 6500+ with an OE hydraulic lifter cam and 7000+ with an OE mechanical lifter cam.

Plus the Sealed Power VS77 equivalent costs about a buck a piece.

I go by the creed: If it works, don't fix it!

Duke

We're not talking about price here.....were talking about effectiveness and durability.

[Joe C.]

Re: Crane Cams is BACK!!!

There you go again Joe, using "advance" and "retard" in vague, nonsensical hot rod lingo. Engineers don't deal with such foolishness.

You should note that I speak in terms of valve opening and closing points and "phasing", and the inlet lobe is most important because of the effect of its phasing on the position of the torque curve on the rev scale.

Most vintage OE cams have an inlet POML in the range of 108-110 deg. ATDC, and I used this range as a benchmark. If a cam has an inlet POML later than 110 I call that "late phased", and vice versa.

Note that many high overlap aftermarket cams try to make up the lost low end torque by phasing the inlet valve early - about 106 deg. ATDC inlet POML, but then the thing drops dead at 6000 revs, where an OE cam of similar duration and less overlap will keep making power another 500 to 1000 revs higher, in addition to making better low end torque. It's like trying to jam a square peg in a round hole.

The LS7 cam is an excellent example of modern valve timing that is matched to the flow characteristics of the engine with a very road worthy torque bandwidth spec - modest duration, late phased inlet valve, and a wide LSA for low overlap. The exhaust duration is longer with a very early phased exhaust event because GM purposely made the exhaust valve and port restrictive in order to achieve the largest inlet valve/port possible, but this can be compensated with an early opening exhaust valve, which is what you get with 230 deg. .050" duration and a POML of 127 deg. BTDC. That's VERY early phasing compared to a vintage OE or aftermarket cam.

I follow the same basic philosophy with my designs to replace the OE 300 HP cam, however, there's a twist. As machined by Flint the E/I ratio is about 0.65 (same as the LS7), which, as is the case with the LS7, responds well to longer exhaust than inlet duration to yield an early opening exhaust valve.

However, massaging OE big port heads yields an E/I ratio in the range of 0.75-0.80. With such a free flowing exhaust (compared to the inlet) a late phased exhaust event with shorter exhaust than inlet duration is the key to broad torque bandwidth.

Another way to look at lobe phasing is to look at the "split overlap" point, which is where the point of equal valve opening occurs relative to TDC. On most vintage engines it is before TDC. On the McCagh Special cam it's 7.7 deg. after TDC. EA will tell you the point within a few degrees, but EA's cam models assume symmetrical lobes. Most OE lobes are asymmentrical with a slower closing than opening below .050" lift so the actual split overlap point is several degrees later than what EA reports. The 7.7 deg. is based on the lift data from the GM drawing for the lobes with the inlet POML at 116 deg. ATDC and the exhaust POML at 108 deg. BTDC.

My first design forced an early split overlap point due to 20 degrees more inlet than exhaust duration. Though it made L-79 top end power with 300 HP low end torque, it did not meet my peak power and revs expectation. After the dyno numbers were in I set up an isentropic flow analysis on Excel covering the beginning of the exhaust stroke to the end of the inlet stroke, which includes the overlap period. I used lift right off the GM drawings so (for an isentropic analysis) I believe it is accurate.

What it told me is that at high revs the early closing inlet valve builds up high pressure as the piston approaches TDC, which increases pumping work and dilutes the incoming fresh charge - a double downside whammy. The analysis showed that my cam design has double the pumping power loss of the L-79 cam, which has a much later closing exhaust valve. The algorithms in EA are apparently are not sophistiated enough to pick this up, which is probably why the actual engines did not meet EA's prediction

So for the next design I shortened both durations with only 8 more degrees at .050" on the inlet side and phased everything late so the exhaust valve hung open much longer than before while maintaining the same effective overlap.

The test engine has a torque curve nearly as flat as Nebraska. In addition, it made EA's predicted top end power with more low end torque than predicted. I was happy with the performance and the owner had a ball scaring the sh...t out of the PV judge!

In the case of the LS7 cam it has a late phased inlet event and early phased exhaust event (relative to vintage OE cams). These combine to yield a very wide LSA and low overlap. The valve timing is very well matched to the head flow and is the reason why the LS7 provides torque bandwith that is unobtainable in a vintage engine with conventional vintage engine valve timing.

Valve timing has to take into account the relative flow of the the two ports and the torque bandwidth specification. Simplifying this to typical hot rod terms like LSA, advance, and retard looses site of the complex physics that is going on inside IC engines, and is the reason why most aftermarket cam designs are poor choices for broad torque bandwidth road engines.

The sacred cow "LSA" is not a design parameter, but most hot rod types think it contains some kind of magic. I design by indepently optimizing the inlet and exhaust phasing to get the broadest torque bandwidth once I have selected durations that take into account the E/I ratio. LSA is just a simple number that falls out out of the final design valve events, but I could care less what it is, as long as, in the case for my 300 HP replacement designs, that the effective overlap (that EA tells you) is maintained at about 0.9 sq-in-deg, because maintaining that value is critical to maintaining the 300 HP engine's idle characteristic - butter smooth 500 in neutral with about 18" Hg manifold vacuum

If you only understand valve timing through the myopic lens of hot rod magazines and aftermarket cam catalogs, you will never understand the big picture.

Duke

Respond to post # 27 directly, without the smoke and mirrors.

[Joe C.]

Re: Crane Cams is BACK!!!

Respond to post # 27 directly, without the smoke and mirrors.

Duke...............you alright? I hope I didn't hurt your feelings too badly.

No response, so I'm wondering if you didn't stick your head in the oven.

Please respond.

Oh, I feel so guilty!

[Jack H.]

Re: Crane Cams is BACK!!!

....
It's still an okay cam for a 283, especially with less overlap, but I still recommend the LT-1 cam for 327s and 350s.
Duke

Duke and anyone else with an opinion on the subject...

I plan to completely rebuild my 1967 327 and generally return it to L79 specs. I already have a new SpeedPro version of the L79 cam waiting to be installed.

However, I'm a big fan of horsepower/torque/drivability (aren't we all?), and was wondering if there is cam selection that would be better, i.e. maybe the LT-1 cam you mention above?

For additional info, I'll be running the stock alum intake, stock Holley 3810, L2166 SpeedPro pistons, 2.02 heads that have been unshrouded in the bowl area, etc.

Thanks,
-Jack

[John R.]

Re: Crane Cams is BACK!!!

Since this thread is about Crane Cams, can anyone tell me what engine a Crane Cam Part # 134822, Fireball II 302H applies to or can direct me to a site that will tell me? Have one new in the box. Thanks!

[Jack H.]

Re: Crane Cams is BACK!!!

Since this thread is about Crane Cams, can anyone tell me what engine a Crane Cam Part # 134822, Fireball II 302H applies to or can direct me to a site that will tell me? Have one new in the box. Thanks!

http://cranecams.com/?show=browsePar...tType=camshaft
'67 Up BB Chevy 396-454. This would have been an aftermarket grind, i.e. not OEM.

[Duke W.]

Re: Crane Cams is BACK!!!

Duke and anyone else with an opinion on the subject...

I plan to completely rebuild my 1967 327 and generally return it to L79 specs. I already have a new SpeedPro version of the L79 cam waiting to be installed.

However, I'm a big fan of horsepower/torque/drivability (aren't we all?), and was wondering if there is cam selection that would be better, i.e. maybe the LT-1 cam you mention above?

For additional info, I'll be running the stock alum intake, stock Holley 3810, L2166 SpeedPro pistons, 2.02 heads that have been unshrouded in the bowl area, etc.

Thanks,
-Jack

That's been done - L-79 converted to a "327 LT-1". Well massaged heads will yield about 325-350 net horsepower with a useable power curve to over 7000. Better con rods are mandatory unless you want to take a big chance on a blowup.

If the clearance is set properly there is no hint of a mechanical lifter cam, but the idle will be a little rougher with 12" @ 900 versus about 14" @ 750. A PV may be touch and go depending on the judge.

Everything else the same the the L-79 will cam produce slightly less power with about 6500 useable revs - a little more low end torque, but the difference is not huge. The biggest advantage of the LT-1 cam is extending the usable rev range where near peak power is available. Peak power with either cam will depend on how well the heads flow.

I have no opinion to offer, but if you want facts, search "327 LT-1" and you will find the system engineering analysis, configuration details, and test results for the two that have been built including some references to threads on The Corvette Forum going back several years.

Duke

[Tom P.]

Re: Crane Cams is BACK!!!

I was hoping someone would expand a little more on the use of the beehive spings in Gen1 style heads combined with lifts in the range of .500. Anyone?

[Duke W.]

Re: Crane Cams is BACK!!!

Different subject. You should start another thread.

Duke

[Joe C.]

Re: Crane Cams is BACK!!!

I was hoping someone would expand a little more on the use of the beehive spings in Gen1 style heads combined with lifts in the range of .500. Anyone?

Use Comp Cams spring number: 26918, and install them @1.850.

[Clem Z.]

Re: Crane Cams is BACK!!!

I was hoping someone would expand a little more on the use of the beehive spings in Gen1 style heads combined with lifts in the range of .500. Anyone?

here is a write up about bee hive springs. http://74.125.47.132/search?q=cache:...&ct=clnk&gl=us

[John H.]

Re: Crane Cams is BACK!!!

here is a write up about bee hive springs. http://74.125.47.132/search?q=cache:...&ct=clnk&gl=us

Comp Cams' advertising guys would like you to believe that they invented and developed the beehive valve spring, but they didn't. The beehive springs were developed by Mahle - we used them as OEM on the Viper V-10 beginning in 2002.

[Dick W.]

Re: Crane Cams is BACK!!!

If my feeble memory is not failing me, I have seen beehive springs on older engines, 1900's, maybe to early teens.