[PAUL K]

Originally Posted by wovenweb

Old technology does not = bad technology. Only bad technology = bad technology.

Truth

[Skip Fix]

"Let me simplify it, with this question. Will using 1.65 rockers put more strain on the pushrods, lifters and cam lobes, than using 1.5 rockers ?"
Figure EVERY BBC has had 1.7s(348-409s 1.75) BBF 1.7 + , every LS motor in trucks and cars 1.7+.

Yes it will put some mechanical stress more than a 1.5 but figure all these factory motors had even higher than 1.65s it must not be that bad.

[b-man]

Originally Posted by steverino

Funny, when calling the "tech line" at comp for cam selection advice, I had that "cubicle" feeling after hanging up

Obviously a popular topic here, lots of good info and shared experience , including that last link to more great experience shared by Jim Hand

I also feel that it's two different worlds between HR and HFT cams, and don't see myself considering the HR route anytime soon , so am focusing on the HFT info

I am also uncertain if I'd like the Rhoades lifters (restored stock looking gto convert), but I'd really like to hear them in person if there's anyone in central/eastern MA , southern NH that is running them ? Maybe I could catch up with them at an event somewhere over the summer

On the other hand, (and seemingly supported by that last Jim Hand article linked), I may not absolutely need the variable lifters if I were to switch to an 041 style cam, since I have a manual trans and manual brakes ? (currently I have 14" vac @ idle)

So I'm also wondering if anyone uses an 041 in a 455 with standard lifters , and with 1.65 or 1.5 rockers ?

I guess at 9.4 I could use an 041 cam, but if I wasn't planning to try the Rhoades lifters, what option might I have ?

It's obvious that the Rhoades with certain cams (041 etc) are a proven performer, but what about HFT options with standard lifters ?

My current "plan B" (if dissatisfied with the xe274), was/is the crower 60243 , but I'm not sure how much of a difference I would experience or if it would be worth it

I'd go right ahead and run the 041 with standard lifters, 1.65 rockers and 9.4:1 compression. Your car has a stick trans and manual brakes, nothing should be stopping you from using that combo in a street 455.

Originally Posted by ponyakr

"...Under a different part number however because of the different distributor drive gear it reappeared as the 455 SD cam."


So then, I suppose you could say the 744 grind ran OK in a fairly low comp 455 ? They had originally planned to used the 041 grind cam in the SD455. I've read that it should not be used below about 9:1 CR. So, how would that have turned out ? That brings up the question, what is the minimum CR for an 041 cam in a 455 ?

Just can't help it. I love to read this Jim Hand stuff.

http://www.dapa.org/building-a-stron...iac-camshafts/

I've never used the 041 cam, but I have used 2 bigger cams than the 041 in a 455 with less than 9:1 compression. Ran the H-O Racing HC-02 (231/243,.512"/516" w/1.65 rockers) and the HC-03 (244/252, .550"/.554" w/1.65s). Only ran the 02 cam for a short time before switching to the 03 cam, in a standard-bore 455 with #197 HO heads at around 8.6:1. It ran great and had low vacuum at idle as expected, manual brake car so it didn't matter.

Sure, higher compression would have been better, but in my situation I was using the parts I had on hand along with the camshaft recommendations straight out of the H-O Racing catalog. The HC-03 was recommended for the 455 HO (a known low-compression engine, right?) with lower gearing, I was using 3.89 cogs with a 28" tall tire:http://forums.maxperformanceinc.com/...5&postcount=19

[61-63]

Originally Posted by Skip Fix

"Let me simplify it, with this question. Will using 1.65 rockers put more strain on the pushrods, lifters and cam lobes, than using 1.5 rockers ?"
Figure EVERY BBC has had 1.7s(348-409s 1.75) BBF 1.7 + , every LS motor in trucks and cars 1.7+.

Yes it will put some mechanical stress more than a 1.5 but figure all these factory motors had even higher than 1.65s it must not be that bad.

I don't see how there will be more stress if you change the valve springs and maintain the same seat and open pressures, but yes more stress if you leave the same springs in and thus the open pressure with 1.65 rockers are greater than they were with the 1.50 rockers. If you are building an engine from scratch and buy springs that will give you the pressures specified for the cam, matched to the valve lift, the stress will be the same regardless of rocker ratio. 1.65 rockers will use a slightly lower spring rate than will 1.5 rockers. Or am I missing something here?

I've been lurking and have enjoyed this thread.

[ponyakr]

And the survey said: 185 posts.

This is a very popular thread. And to me, it's real similar to some of the "which alum heads are better" threads. It seems to depend on who you ask. If you say the steep ramp cams are not too good for a 455, somebody will come on telling how great their engine runs with an XE cam. And if you say Rhoads lifters work good, somebody comes on telling of their bad experience with 'em.

One will say rollers are better in most all situations. Another will say that certain flat tappet hyd are almost as good as a very popular roller. And on and on it goes.

So I wonder if some of you guys who really know what's going on, can agree on at least some basic guidelines for 455 cam specs.

Since this is the street section, lets assume 9-9.5CR, with unported iron heads, 3600lb car, 3-speed auto, stock converter, 3.08-3.23 gears.

Advertised duration: The steep ramps advertise 256 & 262 for their smaller cams. The 041 is sometimes said to have 308/320. So, for the combo mentioned, what advertised would be considered too low and might cause detonation? And how much would be considered too high, for 9.5 CR ?

Dur @ .050 lift: The smaller cams are in the 2teens. The 041 is around 231/240. So, what would be the best range for this app, to give a good idle, plenty of vac, and decent power to 5000rpm ?

LSA: I've read everything from about 106 to 115. Again, for good idle and vac, narrow the desirable range down some. 110-112 ? 112-114 ? or ?

Lift: .407-.525 What's a good range, for good performance, without high spring pressures ? .425-.475 ? .450-.500 ? or ?

Now--with your answers to those questions, list some shelf cams which you would recommend, which fall into this category. This is to help those who are trying to decide on a cam for their engine, to narrow their possible choices.

I'll go 1st, whether I'm right or wrong. I personally consider the 068, with 1.5 rockers just too small for a 455. So, the smallest combo I'd consider is an 068, with 1.65 rockers. But, since the Summit 2801 is basically a high lift version of the 068, I'll make it my #1 choice for the smallest cam I'd use. My choice for the next larger size is the Summit 2802. Then I'll go with the Crower 60243. And, of course, the cam I'd actually use in my 455 would be the 041 grind, with Rhoads lifters. I can see no reason to go with a cam any larger, for this app. Again, I'm not talkin about max hp, or lowest ET, but a good, highly streetable pump gas HFT cam for the app mentioned.

So, let's see what you guys recommend. No special custom grinds, just name brand cams that a guy can order online, from somebody's shelf.

[screamingchief]

Originally Posted by ponyakr

I assume this "bullnose" is similar to the NHRA Stocker grind profiles, just not as pronounced. Is this correct ?

Yes,very much the same basic concept.

When lift is limited,and all you can do is add duration,the nose up-over peak lift will have to flatten out to one degree or another (no pun intended).

And I know you learned a bunch more about that deal after spending some time over @ the stocker forums @ classracer.com.

Originally Posted by ponyakr

What exactly was the higher spring pressures that Pontiac used on the RA3 and SD455 engines, with this 744 grind cam ?

I dont have the specifics in front of me right now,nor do I have them memorized,but FYI they had to use a taller IH in most all the engines that used that 744 cam,and being a low lift cam that added IH was'nt there to add clearance or such,it was there to allow for the use of stiffer springs,and as was mentioned they quickly moved away from using the 744 cam @ all due to it's inherent problems.

Only reason the SD455 used a version of the 744 cam was they could'nt get the 041 version smog legal for the SD455,and remember '73 was a big rollout year for smog equipment,so they were sorta caught behind the 8 ball on that deal and they had to do what they had to do.

The 744 cam is nothing like the modern cams that are roughly the same,the modern cams will have nowhere near the same amount of seat duration,and the additional lobe lift allows for a much better nose profile.

There is a long thread here about the 744 cam,with pics comparing the 2 lobes you mention IIRC,and it's a night & day difference.

As for the rocker ratio deal,as was mentioned if using the same springs,of course there will be more stress on the valvetrain with a higher ratio rocker,that's simply because any time the lobe is off the base circle there's going to be a higher lift seen @ the valve and the springs rate determines where the open pressures will end up with any given lift @ the valve.

It's not that more force is required to lift the valve,as you mentioned Don that's more or less a constant with a given spring set-up,it's just that you are going to be lifting the valve open sooner (and afterwards opening it further) with the higher ratio rocker,as it is effectively adding duration/lift to a given lobe just as soon as it cracks the valve off the seat.

But as Steve C. alludes to,there's waaayyy more to spring pressure dynamics that dictate whether more/less spring pressure is "better",even for street use.

Seat pressure is all about preventing the springs from bouncing off the seats when the valves are closed,go too light on the seat pressures and you'll kill a cam quicker that way than you would've by using too much seat pressure.

And open valve spring pressure is all about preventing floating the valves or "lofting" the lifters off the cam at/around peak lift,again making for a very short lived cam & valvetrain.

It's a fine line between "not enough" ~ "just enough" & "too much"...

So yeah,less is'nt always better when it comes to valve spring pressures.

And yes,using a lower ratio rocker during cam break in is another measure often used to help that process.
Some cam co's even offer low ratio rockers (1.2/1.3 ratio) for exactly that purpose.

HTH

Bret P.

[screamingchief]

Originally Posted by ponyakr

Since this is the street section, lets assume 9-9.5CR, with unported iron heads, 3600lb car, 3-speed auto, stock converter, 3.08-3.23 gears.

IMO,right off the bat that is bit of a mismatched combo.

That's simply because there's no valid reason to even push the CR to 9.0-9.5 for a mild "street" combo like that.

Stock converter and low numeric gears like that are gonna complicate the cam selection options somewhat.

Now lets say it's a 9.5:1 455 w/a 2500 converter and 3.42 gears and yeah your cam options tend to open up somewhat.

This is where cam selection becomes entirely subjective,hence why you'll never get the concensus you seek,as the devil is in the details as they say.

What cam I might choose myself is not always what I would recommend to someone else.

Without knowing who's car it is,and what they're goals are for the combo,this would largely be an excersize in hypothesizing,and that sorta thing is mostly a waste of time IMO.

The "one size fits all" paradigm for cam selection does't work well if you ask me.

It's strictly a case to case basis.

FWIW

Bret P.

[ta man]

Originally Posted by ponyakr

And the survey said: 185 posts.

This is a very popular thread. And to me, it's real similar to some of the "which alum heads are better" threads. It seems to depend on who you ask. If you say the steep ramp cams are not too good for a 455, somebody will come on telling how great their engine runs with an XE cam. And if you say Rhoads lifters work good, somebody comes on telling of their bad experience with 'em.

One will say rollers are better in most all situations. Another will say that certain flat tappet hyd are almost as good as a very popular roller. And on and on it goes.

So I wonder if some of you guys who really know what's going on, can agree on at least some basic guidelines for 455 cam specs.

Since this is the street section, lets assume 9-9.5CR, with unported iron heads, 3600lb car, 3-speed auto, stock converter, 3.08-3.23 gears.

Advertised duration: The steep ramps advertise 256 & 262 for their smaller cams. The 041 is sometimes said to have 308/320. So, for the combo mentioned, what advertised would be considered too low and might cause detonation? And how much would be considered too high, for 9.5 CR ?

Dur @ .050 lift: The smaller cams are in the 2teens. The 041 is around 231/240. So, what would be the best range for this app, to give a good idle, plenty of vac, and decent power to 5000rpm ?

LSA: I've read everything from about 106 to 115. Again, for good idle and vac, narrow the desirable range down some. 110-112 ? 112-114 ? or ?

Lift: .407-.525 What's a good range, for good performance, without high spring pressures ? .425-.475 ? .450-.500 ? or ?

Now--with your answers to those questions, list some shelf cams which you would recommend, which fall into this category. This is to help those who are trying to decide on a cam for their engine, to narrow their possible choices.

I'll go 1st, whether I'm right or wrong. I personally consider the 068, with 1.5 rockers just too small for a 455. So, the smallest combo I'd consider is an 068, with 1.65 rockers. But, since the Summit 2801 is basically a high lift version of the 068, I'll make it my #1 choice for the smallest cam I'd use. My choice for the next larger size is the Summit 2802. Then I'll go with the Crower 60243. And, of course, the cam I'd actually use in my 455 would be the 041 grind, with Rhoads lifters. I can see no reason to go with a cam any larger, for this app. Again, I'm not talkin about max hp, or lowest ET, but a good, highly streetable pump gas HFT cam for the app mentioned.

So, let's see what you guys recommend. No special custom grinds, just name brand cams that a guy can order online, from somebody's shelf.

068

[Steve C.]

What cam to use ? A computer cam selection ?

Many years ago Denny Wyckoff at Motor Machine & Supply in Tucson along with David Vizard developed a program called 'Cam Master', a comprehensive computer program that offered precise cam selection. It was a empirical program based on over 50,000 individual engine dyno pulls on various engine combinations. Written up in National Dragster and other magazines. Cam Master was not duration-driven but overlap-driven. The event timing of the cam, dictated by the duration of the intake and exhaust, together with the lobe separation and the advance/retard position in the engine. Once the overlap to suit a given application is decided, everything else falls into place. And it thrived on maximum valve lift !

For interest using the program on one senerio for a 4.210 stroke/462 Pump Gas combo. In part, it was based on 76 degrees overlap. The program used 70 to 90 degrees overlap for a street/strip application. Input: solid roller cam, 1.65 rocker ratio, peak power rpm 5800, using a 2.150 diameter intake valve with 313 cfm cylinder head flow at .600" lift, 6.625 rod length, intended 9.95 static compression ratio.

The results came back with a cam suggestion using a vary narrow 106 lobe LS and a suggested 286 degrees intake duration at .20" tappet lift.

Interesting because at the time it just so happen UltraDyne had a solid roller rated with 286 degrees @.020" tappet lift, 253 at .050", and 0.4033" lobe lift .... 0.665" gross lift. In the actual engine, that had a piss poor 9.7 compression with alum heads, I used a XE solid roller with 254 degrees intake duration at .050", ground on a 108 lobe separation and .... 0.620" valve lift (it was a street engine). To good to be true, peak power on the dyno was at 5800 with a Performer RPM intake and 6000 rpm with a single-plane intake.


.

[Steve C.]

For interest, similar from about 13 years ago by Ken Crocie. A 455 based combo, about 285-288 cfm 'cleaned up' alum heads, 10.2 compression, Performer RPM intake, a 'big' Comp 320H hydraulic flat tappet cam with 268 degrees at .050", 110 LS and 0.606" net lift at the valves.

Produced the exact same peak power at 5800 rpm on the dyno. Like Cliff eluded to here, if you examine the actual lift curve at the valves, this modern quick-lift hydraulic flat tappet cam, in conjunction with high-ratio rockers and Rhodes Vari-Duration lifters approximated the valve-lift curve of a traditional solid roller to about .600" valve lift. But it's going to take additional intake duration.

.

[neill]

Excellent thread. I have a 9.0 to 1 455 with a comp 275 deh and its always on the edge of detonation with 91 octane. The Crower 60243 and howards 410051-14 285-295,231-241,114 both look like better choices to me than the 275. does anyone have any experience with these cams? Thanks for any input.

[Skip Fix]

"It's a fine line between "not enough" ~ "just enough" & "too much"...

So yeah,less is'nt always better when it comes to valve spring pressures.

And yes,using a lower ratio rocker during cam break in is another measure often used to help that process.
Some cam co's even offer low ratio rockers (1.2/1.3 ratio) for exactly that purpose."

I have some SBF 1.33 ratio break in rockers I got form Paul Spotts years ago I used on my current pump gas motor.

I would bet most of the time we really don't know what EXACT spring pressure is the best unless we had a Spintron! And whether you actually loose performance if you are loosing pressures you would only know by track times in a consistent vehicle.

And gosh start talking duration splits 4,6,8,12 degrees, single pattern or reverse split and you open a whole new can of worms compared to what a Pontiac "has to have".

[gtofreek]

Denny Wykoff, haven't heard that name around these parts in years. I knew Denny years ago, I think while he was working on that program, or shortly after he did it. He was telling me about it one day. Never used it though. Not sure what Denny is even doing now. He sold Motor Machine off years ago.

Originally Posted by Steve C.

What cam to use ? A computer cam selection ?

Many years ago Denny Wyckoff at Motor Machine & Supply in Tucson along with David Vizard developed a program called 'Cam Master', a comprehensive computer program that offered precise cam selection. It was a empirical program based on over 50,000 individual engine dyno pulls on various engine combinations. Written up in National Dragster and other magazines. Cam Master was not duration-driven but overlap-driven. The event timing of the cam, dictated by the duration of the intake and exhaust, together with the lobe separation and the advance/retard position in the engine. Once the overlap to suit a given application is decided, everything else falls into place. And it thrived on maximum valve lift !

For interest using the program on one senerio for a 4.210 stroke/462 Pump Gas combo. In part, it was based on 76 degrees overlap. The program used 70 to 90 degrees overlap for a street/strip application. Input: solid roller cam, 1.65 rocker ratio, peak power rpm 5800, using a 2.150 diameter intake valve with 313 cfm cylinder head flow at .600" lift, 6.625 rod length, intended 9.95 static compression ratio.

The results came back with a cam suggestion using a vary narrow 106 lobe LS and a suggested 286 degrees intake duration at .20" tappet lift.

Interesting because at the time it just so happen UltraDyne had a solid roller rated with 286 degrees @.020" tappet lift, 253 at .050", and 0.4033" lobe lift .... 0.665" gross lift. In the actual engine, that had a piss poor 9.7 compression with alum heads, I used a XE solid roller with 254 degrees intake duration at .050", ground on a 108 lobe separation and .... 0.620" valve lift (it was a street engine). To good to be true, peak power on the dyno was at 5800 with a Performer RPM intake and 6000 rpm with a single-plane intake.


.

[Cliff R]

You only have to put a roller cam and flat cam side by side to see why a roller can "get it done" with less seat timing. The ramps are extremely "steep", and the valves reach full lift quickly, and stay there for quite a few degrees of engine rotation. To "mimic" this deal with a flat cam, you are going to have to have more duration (seat to seat), which will degrade idle quality with any given cam profile. We add the Rhoads lifters to take away some effective seat timing at low rpms, or variable duration. Then we add high ratio rockers to get the actual valve events more on par with roller profiles. This is often referred to in this business as "area under the curve". The high ratio rockers let us do more with less, in terms of movement of the tappets per cycle. They may add a bit more stress to the parts as some have eluded to, which is never a good thing with flat cams/lifters.

So in basic terms, a very well chosen HR cam topped with Rhoads lifters and high ratio rocker arms is basically a "poor mans roller cam" set-up, and it does make great power at a fraction of the cost of a complete roller cam set-up.

In recent years, we switched to roller set-ups not so much for the power, but to take "scrubbing" a lobe out of the equation. I still like flat cam set-ups, and we are now experimenting with coating flat cams for improved durability. I really think that it will work well, as this technology has been out there now for quite a few years. We're about to put our first one in service, in a 412cid Pontiac engine. We polished the cam in our shop lathe and sent it out to be coated. It just got back and we're finishing the assembly in the next week or so.

I really think that coating the cams will be the hot ticket and we may start going back to flat cams for a lot more of our engine builds, as I love the ability to use the Rhoads lifters and high ratio rocker set-ups, and at this time I'm not overly fond of any of the hydraulic roller lifters being produced (retro-fit). I've had numerous issues with them, including the engines going "dead" at high rpm's. The "hybrid" set-ups (HR cam/HIPPO solid roller lifters) in contrast will rev right past 6000rpms so fast you can't move the shift quick enough!

It may be some time before we know how well the coated stuff is going to work, but I'll make sure to post the results as they happen.....Cliff

[Skip Fix]

Steve I think I had them run the same cam program for me for my first E head motor and it was a pretty unusual recommendation with LOTS of lift.

[Steve C.]

Your right Skip, Cam Master did recommend lots of valve lift, and often not an achievable amount. And within his tech material presented David Vizard himself is a proponent of lots of valve lift.

With the scenario I just mentioned the results suggested 0.4980" lobe lift, or 0.747" gross lift with a solid roller cam as input. With the computer results topping the list was valve lift. Bottom line, the engine wants all the lift it can and thrives on it so run as much as mechanically achievable or prohibitive to you because of cost and/or budget limitations (such as in a purchase for solid roller cam, longer valves to increase installed height, stronger springs, etc.). Obviously if it's a street application or race application will have a bearing on the situation, most here would be hesitant to run 0.700 lift on the street.

This info published by David Vizard, it might be of interest:

VALVE LIFT.
"A 2-valve cylinder head typically continues to flow more air up to lift values equal to as much as 0.35-0.4 times the valve diameter. The reason for this is that there is a flow pattern transition period that takes place at a lift value of about 0.25 of the valve's diameter. When this point is passed, if the port has been modified to support flow in this lift region, the valve efficiency actually starts to increase. This is the reason why a 2-valve engine responds to high lift."

"If you want to build a street motor with the most power without a sacrifice of idle and low speed qualities, then lift is the most important factor to maximize, not duration. The best street cams are those that seek to maximize lift while only adding a minimal amount of duration."


.

[steverino]

Thanks for response B-man, I figured if it drove well with the manual brakes, I'd leave a little "room" for cam selection, and figured that with standard lifters I could get by, although it took a bit to get the idle smoothish with the tripower and 274, and I'd probably appreciate the smoother idle the rhoades would provide, I'd be interested to hear them in person before committing to using them.

But we did not clearance the heads for 1.65's while they were off last year (should have been done, I did ask him to), so I would likely be staying with the 1.5's, although it seems that cam (041) can do reasonably well with the 1.5's

If this engine continues to run reasonably well, it may just stay the way it is .....good to have a "plan B" though

[Will]

Originally Posted by Cliff R

... The "hybrid" set-ups (HR cam/HIPPO solid roller lifters) in contrast will rev right past 6000rpms so fast you can't move the shift quick enough!
...

I still don't understand the reasoning behind this. Why not just run a solid roller grind? Is it the difference between a hydraulic and solid roller lobe profile you're after? Less spring pressure needed or something?

Would be good if those coatings end up working but wondering how long it will take before any long-term results are known. I really couldn't care less about the noise Rhoads lifters make, it's the sound the engine makes at 5000 RPM that I'm after!

[rohrt]

Originally Posted by Cliff R

In recent years, we switched to roller set-ups not so much for the power, but to take "scrubbing" a lobe out of the equation. I still like flat cam set-ups, and we are now experimenting with coating flat cams for improved durability. I really think that it will work well, as this technology has been out there now for quite a few years. We're about to put our first one in service, in a 412cid Pontiac engine. We polished the cam in our shop lathe and sent it out to be coated. It just got back and we're finishing the assembly in the next week or so.

I really think that coating the cams will be the hot ticket and we may start going back to flat cams for a lot more of our engine builds, as I love the ability to use the Rhoads lifters and high ratio rocker set-ups, and at this time I'm not overly fond of any of the hydraulic roller lifters being produced (retro-fit). I've had numerous issues with them, including the engines going "dead" at high rpm's. The "hybrid" set-ups (HR cam/HIPPO solid roller lifters) in contrast will rev right past 6000rpms so fast you can't move the shift quick enough!

It may be some time before we know how well the coated stuff is going to work, but I'll make sure to post the results as they happen.....Cliff

With what material did you use to polish the cam? was it really necessary if sending it out for coating?

How will you know if its the coating that saves the cam or just being one of the lucky ones that doesn't have a problem?

[Cliff R]

The "hybrid" set-up takes the hydraulic action of the lifters out of the equation, so they will rev right past where HR lifters give up without additional spring pressure. Really tight lash is required when doing this, so it's not for everyone. If they made better HR lifters, designed from the ground up as "limited travel" and for high rpm use, I'd go that direction instead.

I have noticed they are making changes to the HR lifters, even though they (the folks making or selling them) aren't saying much about it. The spring in the bodies is stiffer in recent units, and they have shortened the travel up a bit, but I'm not sure if they will rev harder or work any better at high rpms with "standard" weight parts than the earlier designs?

As for the cam polishing, we used super fine auto body sandpaper, starting out with 600 grit and clear up to 1500 finish, or basically a "mirror" finish. They have been coating NASCAR cams for many years, and claim zero issues anyplace. We'll certainly find out, as we hope to have our engine in use and start flogging on it in the next few weeks.......Cliff