[quicksilver97ta]

Comparing two Crower cams (60919 vs 60244), Looking at the valve timing events I came up with a question. On a given cam like the 60919 why would you, and what would be the effect of having 4* more .050 intake duration when opening the valve and leaving it open 4* longer at .050? I know the cams are not identical other than the intake events but that looks like the biggest difference, ramp rates being second. Or do I have that the other way around?

Is there a total effect, for example, is this something you would attempt to correct poor low lift intake flow? Is this not too unlike running 1.6 intake rockers and 1.5 on your exhaust, what does that "fix" when the car runs better that way?


60919- 304/316 : @.050 231/240 : intake opens 7.5 btdc closes 43.5 abdc : exhaust opens 56 bbdc closes 4 atdc

60244- 297/308 : @.050 240/242 : intake opens 12 btdc closes 48 abdc : exhaust opens 57 bbdc closes 5 atdc

[screamingchief]

but that looks like the biggest difference,

Nope,biggest difference IMO is the overlap numbers.

The 60919 has 84° total overlap,and 10° O/L @ .050".

The 60244 has 78.5° total overlap,and 17° O/L @ .050".

But that said,closing the intake earlier in almost all cases builds more cylinder pressure,but looking at the .050" events for that purpose is misleading,so it's best to look at the seat events for that info,and crower does'nt provide those numbers as SOP,so you gotta sit down and do some math to get those figures.

At the seat,the 60919 closes the intake @ 81° ABDC when installed on a 109° intake centerline.

And the 60244 closes the intake @ 76.5° ABDC when installed on a 108° ICL.

So as you see,the overlap is reduced in the 60244,but a portion of the existing overlap was also "shoved" up the lobe some as well (more O/L @ .050" in spite of less total O/L).

The end affect of all that,a choppier idle,with more cylinder pressure due to the earlier intake closing event when using the 60244 cam.

But all in all they are pretty close in most respects.

HTH.

[67drake]

SC,how did you come up with the seat #'s for a Crower? I've been using this formula.
(Advertised Duration - .050 Duration)/2) + Intake Valve Closing @ .050 = Advertised closing point
I don't know how accurate it is though. Is this what you use,or is there another one.I had to dig this one up out of an old post.

[screamingchief]

To solve for the intake closing event: (advertised or .050",works for both);
Duration / 2 = (XX) + installed lobe centerline = (XX) - 180 = the IC.

To solve for the intake opening event:
Duration - 180 = (XX),then the intake closing event is subtracted from (XX) = the IO.

When doing this on the exhaust lobes,do note the events are flipped,and the first formula is for the exhaust opening event and the second formula does the exhaust closing event.

Thus: (60244)

Intake side:

297 / 2 = 148.5 + 108 = 256.5 - 180 = 76.5° ABDC~IC event.

297 - 180 = 117 - 76.5 = 40.5° BTDC~IO event

And the exhaust side:

308 / 2 = 154 + 116 = 270 - 180 = 90° BBDC~EO event

308 - 180 = 128 - 90 = 38° ATDC~EC event

You can double check the overlap numbers with this next formula as well:

Add intake and exhaust durations (again advertised or .050" whatever your solving for)
divide by 4
subtract LSA
multiply times 2
Equals overlap

Thus: (60244)

297 + 308 = 605 / 4 = 151.25 - 112 = 39.25 x 2 = 78.5° total O/L

Add the IO and the EC events to verify 40.5° IO + 38° EC = 78.5°

Go ahead kids,try that on the cam cards .050" numbers just for practice.

Funny how that works huh...

This of course only truly shows a symmetrical lobe accurately,but you will find that almost all the "advertised" specs on asymmetrical lobes are pretty much the same as these formulas kick out,at most I've seen a half degree "glitch" here or there,but nothing much bigger than that ever shows up so I figure these formulas are OK for basic comparison purposes,short of a cam doctor printout a fella would be hard pressed to be more accurate than that.

The 180 number in the above formulas represents the cams base circle,and it is a constant in those formulas.

HTH.

[Z Code 400]

The new Bullet Flat Tappet looks great, Chief...very nice workmanship coming out of Olive Branch these days....:-)

[screamingchief]

Originally Posted by Z Code 400

The new Bullet Flat Tappet looks great, Chief...very nice workmanship coming out of Olive Branch these days....:-)

Yeah,wont be too long and I gotta call them and get them to grind me one of the old UD solids for the second back-up 400 for the race car.

All I hear are good things about them folks at bullet thus far,I really like that!

Have a good new year Robert!

[67drake]

Thanks,SC.I owe you a kringle!
I've been running #'s on 3 Crower grinds that I'm looking at.The formula that you gave matched 1,and was only .5 degree off on the other 2. So it looks like I did something right.
Thanks again,Drake

[Z Code 400]

The guru sayeth:

Loveth not duration alone, for it will surely buildeth little torque without lift. Tighten not thine lobe centers if thou havest a long stroke....if thine compression be low, alas! reduce thine advertised duration and quicken thine ramps for the moments of low lift flow are at hand. If thine compression be high, the larger numbers will serve thee well.

If thou be one in spirit with me, one who loves to turn rpm, then limit thine stroke to less than a quarter of a cubit, increase thine duration and lower thine gears.

There are those who marvel at a behemoth that turns slowly with much force, but verily I say unto you, if thine liters be great and thou turnest much greater rpm, will thine be even more blessed in the eyes of the guru...:-)

[quicksilver97ta]

Thanks for all the replys. Bret, I have the formula 67drake posted but not the ones you did so I will have some fun crunching those numbers. In your first post I get everything you say except why it would have a choppier idle.
I also reconsidered something in my first post where I thought this application might be for poor low lift intake flow, perhaps it's actually better for a combo with improved exhaust flow and thus is making less compensation for it. Both intake and exhaust advertised durations are about 7-8 degrees more on the 60919 however, the .050 exhaust numbers are nearly the same where the intake shows 4 degrees more on the opening and closing for a total of 8 more degrees at .050. Is that where the choppier idle will come from, more reversion even though the intake valve actually opens later and closes sooner?

[screamingchief]

Originally Posted by 67drake

Thanks,SC.I owe you a kringle!
I've been running #'s on 3 Crower grinds that I'm looking at.The formula that you gave matched 1,and was only .5 degree off on the other 2. So it looks like I did something right.
Thanks again,Drake

Ha,ha,ha,your gonna get a kick outta this Drake!

I was born and raised in Racine Wi. myself,moved here to Tx. my senior year in high school with ma & pa,and I've moved back and forth every so often ever since I graduated high school here,my dad worked at SCJ for like 25+ years,his brother worked there till he retired too,their father worked there also.

My brother lives right across the street from the SCJ headquarters and the golden rondell,get to watch the SCJ helicopter land and take off all the time when it's nice out.

My sister works security for the company SCJ uses,last I recall she works at the SCJ hanger out at Batten field.

But the funny thing is,after all that time & history there,I'm not a huge fan of kringle,dont get me wrong I like a couple of types well enough,but honestly I'm not the biggest kringle fan overall...

Also not the biggest cheese guy either,some types are OK,but others...

Now pizza,we could talk about,pias,buona vita,infusinos sure!!!

My niece works the phone/register at the infusino's in west Racine.

Or subs,,,the meatball bombers at Jerry's,man those are the $#!t!

Hamburgers at the farm or kewpies,good stuff.

And the french dip sandwhich at chubbies,oh man that is just too much food!

And those are just scratching the surface...

Damn I miss the food up there,can ya tell!!!

Was up there for the power tour last year,that was real cool,even though the weather sucked.

Will likely be back up there again this summer.

Will have to get in touch then,hell,we probably know a few of the same people,it's not that big of a town,and the pontiac fans tend to run in the same circles more or less.

I also reconsidered something in my first post where I thought this application might be for poor low lift intake flow,

Of the two cams,the 60919 is clearly the one that thrives on low lift flow,this is evidenced by the fact a large bulk of it's overlap and seat duration is biased to come in very early on the lobe,thus why the .050" specs are less than the 60244,this is very much like the OE pontiac performance cams,and it is widely accpeted that is what the pontiac engineers were after when they designed the pontiac engines,and thus also the cams.

perhaps it's actually better for a combo with improved exhaust flow and thus is making less compensation for it.

I would be willing to bet if we got a chance to bend the ear of said pontiac engine designers they would tell us they found out that the pontiac head design scavenged very well at low lifts in "stock" form,thus the reason why if we look at the OE pontiac cams design,the one thing that constantly is increased when going up the "food chain" is the fact that without exception the overlap increases.

The lift is often the same,the advertised durations are often within a few degrees,the LSA's are the same as well,but for every jump up in "size",there was always an increase in total overlap.

So,it's safe to surmise that they based their choices on these cams based mostly on overlap,they used it to target the power they were after,then used the rest of the specs to "fine tune" the choice of overlap.

My comments about the choppier idle come from the fact that there is a "delay" of the overlap period with the 60244,that part about pushing a portion of the overlap "up the lobe" a bit,this is an attempt to mimick a bigger cam and it is almost always seen when a cams LSA is tightened up to add overlap,this is where tight LSA cams get the "rep" of having nastier idle notes,the delay of the overlap period just seems to allow slightly more charge dilution and thus affects the idle slightly at idle RPMs.

Truth here likely has that a fella would be hard pressed to tell the difference between those two cams from the idle sound alone though.

Even though the 60244 has more .050 duration,it still has less total overlap,and the earlier intake closing event,and thus would be considered the "smaller" cam IMHO.

The "faster" lobes can often make that the case,they are very misleading when you look at just the advertised specs without looking at the valve timing events at both the seat and .050"!

Only then does the "truth" about our cams begin to surface.

Isky and crane are the only cam companies I can think of that include both sets of specs for their cams,and from that I feel the other companies could learn a thing or two.

[quicksilver97ta]

Well hopefully I didn't do to bad a job picking this cam out. I actually bought it 12 or so years ago for my 428 and that was way before I ever heard about fast ramp rates. I just figured the factory ramps were more for stock valve springs than anything else, I guess the marketing is newer than the actual lobe profiles, lol. I originally ran it for a brief time with some lower compression heads but pulled it in favor of a Lunati with less duration. I’m gonna run it again though, it’s what I have laying around and it's practically new, but this time it’s going to get higher compression ported 997 heads to go with it. I have read enough about the popularity of the RAIV like 60916 it’s good to hear that it’s pretty close. That’s about the performance level I’m shooting for. Everything else is fairly matched for it, 3.55 gear, loose converter, dougs, and a tri-power in my 68 firebird whatever that weighs all steel with me in it. I am going to post a very detailed account of SCR and DCR when it’s up and running. Again, thanks for the replies.

[67drake]

[QUOTE=screamingchief]Ha,ha,ha,your gonna get a kick outta this Drake!

I was born and raised in Racine Wi. myself,moved here to Tx. my senior year in high school with ma & pa,and I've moved back and forth every so often ever since I graduated high school here,my dad worked at SCJ for like 25+ years,his brother worked there till he retired too,their father worked there also.

My brother lives right across the street from the SCJ headquarters and the golden rondell,get to watch the SCJ helicopter land and take off all the time when it's nice out.

My sister works security for the company SCJ uses,last I recall she works at the SCJ hanger out at Batten field.

But the funny thing is,after all that time & history there,I'm not a huge fan of kringle,dont get me wrong I like a couple of types well enough,but honestly I'm not the biggest kringle fan overall...

Also not the biggest cheese guy either,some types are OK,but others...

Now pizza,we could talk about,pias,buona vita,infusinos sure!!!

My niece works the phone/register at the infusino's in west Racine.

Or subs,,,the meatball bombers at Jerry's,man those are the $#!t!

Hamburgers at the farm or kewpies,good stuff.

And the french dip sandwhich at chubbies,oh man that is just too much food!

And those are just scratching the surface...

Damn I miss the food up there,can ya tell!!!

Was up there for the power tour last year,that was real cool,even though the weather sucked.

Will likely be back up there again this summer.

Will have to get in touch then,hell,we probably know a few of the same people,it's not that big of a town,and the pontiac fans tend to run in the same circles more or less.




I know this! I read in an old post someplace that you were from around here.
I'm between KR and Taylor,off of Ohio street.Just north of Sanders Park.

[screamingchief]

I know this! I read in an old post someplace that you were from around here.
I'm between KR and Taylor,off of Ohio street.Just north of Sanders Park.

Nice neighborhood.

Back in the day I often got my kegs at Dandees liquor,they can order some awesome import beers in kegs!

Also used to get steaks and meat from time to time at the georgetown village market when I grilled out up there too.

Have an old friend that lives right up the way,just at the corner of 11 and Meachem,right across from Pritchard park.

Knew a couple of girls from that neighborhood back in high school too...

Used to work at what was then the Benjamin/sheridan pellet gun factory off Chickory rd. years ago.

Been to more than a few parties at Sanders park in my days!

That's not too far from great lakes dragaway either,usually drive out that way when I head out there.

Lot closer than the tracks around here...

Yep,know the area well!

[Z Code 400]

Originally Posted by screamingchief

"Knew a couple of girls from that neighborhood back in high school too..."

Yeah....those were the days.......

A few months ago, I got a letter at my parent's home from a girl I dated 19 years ago. She left our hometown to pursue a career in modeling and was in town visiting her family for the holidays.

We got together at a local restaurant and talked about the old days. I was impressed by the fact she remembered my 1967 Dodge Coronet R/T.

Man...those were some good times...Robert

[67drake]

Originally Posted by screamingchief

Nice neighborhood.

Back in the day I often got my kegs at Dandees liquor,they can order some awesome import beers in kegs!

Also used to get steaks and meat from time to time at the georgetown village market when I grilled out up there too.

Have an old friend that lives right up the way,just at the corner of 11 and Meachem,right across from Pritchard park.

Knew a couple of girls from that neighborhood back in high school too...

Used to work at what was then the Benjamin/sheridan pellet gun factory off Chickory rd. years ago.

Been to more than a few parties at Sanders park in my days!

That's not too far from great lakes dragaway either,usually drive out that way when I head out there.

Lot closer than the tracks around here...

Yep,know the area well!

Do you know Wayne Schicantek ?
That's who's doing the work on my 96 heads. Supposed to be the Pontiac guru around these parts. I was supposed to hook up with him today to drop my heads off,but he never answered his phone.Must have took an extra day off.
Yeah,Dandee's is now a McDonalds,Georgetown mart is still there,but Danny the butcher set up a new place of his own on 4 Mile & Charles St.
Your friend across from Prichard,is he a Pontiac guy? I noticed a black 68-69 GTO parked on Ohio St. a few times at the end of the summer.I figure someone must have just bought it.
Get ahold of me the next time you come up,you can check out my "work in progress". BTW,one of the reasons I'm bumping up the performance of the 71' is because I got spanked so bad by the other PY members at Da Grove.
Drake

[screamingchief]

Do you know Wayne Schicantek ?

Personally,no,by reputation yes,Wayne by all reports I've heard is a pretty good guy,and does very good work,one of the best choices for pontiacs in that SE Wisc. area.

Dan Whitmore is/was another,he ported a set of #96's for me a few years back,but he's basically retired at this point from what I've heard,so Dan can be damn near impossible to get ahold of these days,and I'm not even sure just how much work he's doing these days,if any at all.

I think at one point those two worked pretty closely with each other,I think Wayne did quite a lot of Dan's bottom end work or something like that.

Both were in Waukesha at one point I know,though the last time I dealt with Dan he was in Dousmann,he moved his shop out there not too long after I took my heads to him,he also had some health problems around that time,a heart attack and bypass IIRC,then his wife had GB problems,was waiting a while to get my heads done,but the work was very good,well worth the wait.

I've checked out more than a few cars with engine/heads done by Wayne at GLD,talked to a few of their owners,they all were strong runners,owners were happy customers.

So Wayne should have your back!

Yeah,I saw they put the mickeyD's there where Dandee's was,that's OK,plenty of other places to pick up imports,and rarely do "keggers" much anymore...

My friend up the road is more a harley fella,no pontiacs.

Will get in touch next time I'm in that neck of the woods for sure,should have my "driver" '72 bird going by then,may even bring it up!!!



Sorry for the hijack...