[KEN CROCIE]

The HC-63 was 244/252-500/504--same as the HC-03 back in 1978.

[screamingchief]

Originally Posted by HWYSTR455

Those LSAs would certainly have an effect on filling, or packing! the chambers! I think there's no maybe about the secret part!

.

Just an FYI here,those H-O cam listings dont mention the LSA anywhere I can see,what those 108/120 numbers indicate are the repective intake & exhaust centerlines,not the LSA.

You have to add those two and divide that sum in half to get the actual LSA.

108 ICL + 120 ECL = 228 ÷ 2 = 114,so the LSA on that cam is 114°

The fact that the intake centerline is @ 108° means the cam is ground with 6° of advance in it.

Originally Posted by HWYSTR455

Because of overlap, you will bleed below a certain RPM, loosing power, and the DCR will be the giveaway.

Overlap in and of it's own right does'nt "bleed" anything,you can easily have a ton of overlap,and still have a very high DCR (even with a modest static CR),all you need is a relatively "slow" lobe coupled with a fairly early intake closing event to make that happen.

The only way overlap affects the cylinder pressure is by it's ambiguous effect on the end of the cylinder evacuation process,and the start of the cylinder filling process,but that is not very easy to quantify in terms of DCR,not a single DCR calculator has any idea what the cams overlap is,all they care about is when the intake valve is closing.

And with modern "fast" lobes & asymmetric cams,you can confuse that deal even more of you really want to.

IMHO it's always the best course of action to look at the cam card and all the actual valve events if your serious about knowing what is going on with any given cam.

But I digress.

HTH.

[HWYSTR455]

Originally Posted by screamingchief

Just an FYI here,those H-O cam listings dont mention the LSA anywhere I can see,what those 108/120 numbers indicate are the repective intake & exhaust centerlines,not the LSA.

You have to add those two and divide that sum in half to get the actual LSA.

Good catch, only skimmed over the specs and focused on the duration. I did assume the final number was LSA. (And we all know what happens when one assumes!)

Originally Posted by screamingchief

Overlap in and of it's own right does'nt "bleed" anything,you can easily have a ton of overlap,and still have a very high DCR (even with a modest static CR),all you need is a relatively "slow" lobe coupled with a fairly early intake closing event to make that happen.

The only way overlap affects the cylinder pressure is by it's ambiguous effect on the end of the cylinder evacuation process,and the start of the cylinder filling process,but that is not very easy to quantify in terms of DCR,not a single DCR calculator has any idea what the cams overlap is,all they care about is when the intake valve is closing.

You again are technically correct, and my remark was more generic, with 2 indirect points to make, not the same point.

Aside from that, explain then how you feel 'overlap' won't effect DCR?
With an early intake closing as you mentioned, or for example an extreme earlier closing, would there be proper cyl filling on a NA engine?

Originally Posted by screamingchief

IMHO it's always the best course of action to look at the cam card and all the actual valve events if your serious about knowing what is going on with any given cam.

Again this is the best practice, though for arguement's sake, isn't there a 'usual' or predictable pattern to cam's profiles as it pertains to duration & LSA? Compare valve events on 'similar' profiles by several manufacturers are they're going to be within a few degress of each other, correct? There are laws of physics that can't be broken when it comes to cam specs, right?

.

[uneasyrider]

I used this cam in my 4-spd 467, RPM man., 750cfm Q-jet and I was very pleased with the performance and it would run the power brakes, Crower 60243, 284/290, 228/235, Lift With 1.5 Rocker Arms .479/.494, Lift With 1.65 Rocker Arms .527/.544, 112.

[screamingchief]

Originally Posted by HWYSTR455

Aside from that, explain then how you feel 'overlap' won't effect DCR?

This topic could easily fill a book,and even then it would just begin to scratch the surface.

It's pretty basic at it's root though,overlap happens at the end of the exhaust stroke,and at the begining of the intake stroke,so how exactly do you see it significantly affecting the cylinder pressure?

Especially when that point in the engines cycle has almost nothing to do with determining how the cylinder is going to "trap" the existing intake charge to compress it.

The only way it has any affect is by the ambiguous means I mentioned earlier,by affecting the timing and characteristics of the cylinder purging/filling dynamics,and the slight influence that has on the actual density of the intake charge that exists at that point,and thus to a lesser degree,later on when the intake valve indeed closes and the compression stroke does it's thing.

There are two or three main things that primarily affect the cylinder pressure,how much (read:how dense) intake charge gets trapped in the cylinder when the intake valve closes,and the "effective stroke" coupled with the mechanical compression ratio that is used to "squeeze" that said charge,so when talking about overlap,timing is everything,so that could be considered the third thing,actual valve event timing as a whole.

Valve event timing determines the existing charge density @ the start of the compression stroke (#1),the physical charge density determines how much "stuff" that exists to actually compress (#2),and the ES/CR does the rest of the work (#3).

You can absolutely have a bunch of total overlap,but if that overlap is timed for the specific goal of producing a denser intake charge,it can easily add to the amount of intake charge that gets trapped,and not reduce it.

But if the overlap were timed to "bleed" some charge density by letting a portion of the charge back up the intake tract (intake reversion/passive EGR),or when it lets some charge go out the exhaust tract (over-scavenging),then it may indeed "bleed" some of the charge density off,and thus reduce the resulting cylinder pressure due to the timing of that process.

But you cant necessarily predict any of those situations with 100% reliabillity.

It would mostly be trial and error to find what works best for a given combo.

Often the overlap is the end result of a set of other choices that were made in the cams design,ask enough cam designers and a few may even tell you they could care less about it,they'll tell you "it is what it is".

If the bulk of the overlap is happening when the valve is barely off the seat,the intake & exhaust valve "curtains" (read:flow thru area) is relatively low,and the affect of that overlap will be much less than if that overlap happened at greater lifts where more valve curtain area should allow a greater amount of "crosstalk" between the intake and exhaust tracts.

In other words,if one cam has more total overlap,yet has almost none @ .050",and the other cam has slightly less total overlap,yet has significantly more overlap @ .050",which of those two cams would you expect to have a greater affect on the dynamics being discussed here?

Also,understand that you can easily have more total overlap "by the numbers",yet still end up with less overlap "area",and in order to accurately discuss overlap,the actual overlap area in question is rarely ever considered in these sorta discussions,as almost nobody bothers to figure that deal out,and there is no "popular" spec to state such.

Overlap @ lower lifts covers far less area than overlap @ higher lifts does.

And one must also consider there are a whole slew of other influences that come into play,head flow,intake and exhaust tract efficiencies,honestly this topic could easily fill a book all by itself.

Suffice it to say,that overlap taken out of context of the duration,LSA,and actual valve event timing,means almost nothing in terms of all this,it's all relative to the rest of this.

And still not a single DCR calculator requires an overlap input to calculate the DCR.

So the overlap's affect on cylinder pressure is tenuous at best,non-existant at the worst.

What overlap will affect is the power output potential,more overlap generally = more power potential (for a given headflow).

But there is a point of diminishing returns on overlap too (especially with big CID and ample headflow no.s),but like I said,that's all part of a much more indepth discussion,best left for another thread.

Originally Posted by HWYSTR455

Again this is the best practice, though for arguement's sake, isn't there a 'usual' or predictable pattern to cam's profiles as it pertains to duration & LSA? Compare valve events on 'similar' profiles by several manufacturers are they're going to be within a few degress of each other, correct? There are laws of physics that can't be broken when it comes to cam specs, right?

To answer this to it's ultimate "truth",would be to take this thread much further off topic than this has already gone,I could easily post the specs for 5 cams and ask ya'll to tell me which will theoretically do what,but theory does'nt necessarily translate 100% to what will actually be true.

Are there predictable patterns???

At times,,,yeah sure...

But only if a fella takes the time look at absolutely everything that is possible to know.

If that fella is only looking at one or two things,all bets are off.

Results will be hit or miss,mostly a crapshoot @ best.

Laws of physics,I dunno what to say 'bout that,I dont use the laws of physics as it relates to cam selection.

HTH.

[takid455]

thanks for the input. I was able to get a hold of ken and get the HC-03 cam w/ rhodes lifters. I'll just change the gear on the distributor to the non SD gear. cant wait to see how this beast runs.

[gtofreek]

Originally Posted by takid455

I guess my biggest debate between the HO cans and the current cams IS the LSA. when designing a cam, this has a great deal to do with obtaining the best DCR. whist, new cams come close, none of them are near the HO cams which were design for low SCR engines. I spoke with Ken C once about the cams and their design intents and stated that they did in fact design them to achieve the best DCR with low SCR engines. only if he was easy to get a hold of I'd get one of his cams.

Ken C - where are you ?

Ken C works for Kaufman Racing Equipment. I'm sure you can reach him there.

I also like the 231/239 Ultradyne that Oink 1 suggested. That cam makes butt loads of low end torque and has such a flat torque curve to about 5200 in a stock 9:1 455.

[screamingchief]

Originally Posted by gtofreek

Ken C works for Kaufman Racing Equipment. I'm sure you can reach him there.

FYI I'm pretty sure he means Ken Crocie of H-O racing fame.

You know,the fella that posted on this thread already,the guy @ the top of this page.

Not that other fella from Ohio...

[grandville455]

Originally Posted by takid455

thanks for the input. I was able to get a hold of ken and get the HC-03 cam w/ rhodes lifters. I'll just change the gear on the distributor to the non SD gear. cant wait to see how this beast runs.

would like to see that difference too...

[uneasyrider]

Just an FYI for those that aren't as savvy about the cam thing as many of the people that posting here are there is a nice little old book out there called “Basic Cams, Valves, Exhaust Systems” Petersen’s Publishing, 1979 that will give you a good basic, as the title implies, understanding of the above and is now a little piece of automotive flash back. There are articles on how to hop up your Pinto, Dodge Colt, header installation on your Ford Courier, etc. Great stuff to look at 25 years later! They can be picked up on line cheap. I don’t know if there is a newer publication of it or not.

[gtofreek]

Originally Posted by screamingchief

FYI I'm pretty sure he means Ken Crocie of H-O racing fame.

You know,the fella that posted on this thread already,the guy @ the top of this page.

Not that other fella from Ohio...

Yeah I saw that SC. I was wondering why he was asking about the other Ken C[who, by the way goes by Ken C on these boards]. Doohhh! I pulled a Homer!

[speedshopmike]

takid, how's your car coming along?
fired it yet?
-mike

[gto65lvr]

I have the HC-03 in my wagon flat tops 400 with SD 62 heads and an RPM intake runs great on da pump gas pretty impressive. Sounds cool too cannot believe that it has those kinds of numbers @ 050


And to think my IA2 has not much more cam I wanted a driver now wish I put way more cam in it LOL.

[Cliff R]

The Crane 234/242/112 is a great cam in the 455 engine. I'd want to see around 10 to 1 SCR to effectively use it. We've seen dyno runs with that cam in 455's at 10 to 1 SCR with 240cfm heads, it's about on par with the Crower 231/240/113 cam.

Keep in mind that we made 455.4 HP with the Crower 231/240/113 cam using plain old 6X-4 heads, intake matched and basic clean up/bowl hogged to 232/cfm. With better heads, unported KRE aluminum "D" ports, we ran as quick as 11.64 at 3740lbs with that cam. Idles OK, better with Rhoad's lifters and a very broad/flat power curve......Cliff

[Larry Navarro]

Originally Posted by speedshopmike

takid, how's your car coming along?
fired it yet?
-mike

Yeah, is it built yet??

[johnreeves]

Hi All,
Does anyone have any remarks/data on a HC-02D camshaft in low compression (8.5-9.0:1)455 will 3.42-3.55 gearing. After reading the other post on the HC-03 cam some used Rhoads lifters would this also be applicable to the HC-02D grind with a low compression 455? By using Rhoads lifters Does this mean that the cam is a little to big for the application to start with?
Thanks.

[TCSGTO]

I ran the HC-02A back in the 80's in a 9.7cr 455 as well as a 10-1 400 both with Rhoades lifters. I believe the specs were 231/243 @ .050 114LSA with the intake at 107. It idled smooth in gear with the 455 and ran very well in that motor. I had 3.55 gears at the time.

In the 400 it loped and lacked low end with an automatic and 12" converter. The car ran better with a 222/234 @ .050 114 LSA cam with the near stock, original 68 400 engine. I ran it with a 400 4 speed combo too and it was ok in that application from what I remember. Like I said, it was a loooong time ago.

HO Racing was the one of the only games in town in those days and helped us Pontiac guys get through those dark times.

[misaac]

I agree with Gregg and Paul, the UD 231/239@.050 112 LSA is great in a low compression 455. My car is a 4000# pig with a 468, un-ported 96's, and 3.23 rear w/28X9 14" ET Drags. Car is a consistent 13.0@104. On a 180hp hit with the Cheater plate, it runs in the 11.30's@119. My previous Crane cam with a 114LSA went 11.42@117 on a 150hp jetting.

http://www.youtube.com/watch?v=XGf_pe66mOE

http://www.youtube.com/watch?v=obtS3...eature=related

[Sporter]

I ran the Crane 296 with Rhoads lifters and 9.3 5C heads on my 455 for years in my Firebird. Great cam, very mild lope, made 386 rwhp on a chassis dyno, and would get 19 mpg highway with either a lockup 2004r trans or a TKO 5-speed trans. That was with a Qjet, of course.