[Fullsize455]

I'll try to keep this short and simple.. I am building my original 455 for heavy duty street/light duty track duty, and am having a hard time choosing which camshaft to go with. I have decided to go with a hydraulic roller camshaft for sure, to avoid any possible problems with modern oils, and I believe the decreased friction will offer long-term benefits as well when it comes to the life of the motor and such. The extra few hundred bucks up front seems worth it to me.

My basic requirements are simple: As much power/torque as I can make, while still retaining a relatively smooth idle, while keeping it "looking" stock on the outside(heads, intake, exhaust manifolds, etc), and most importantly it MUST run on 87 octane fuel all day long. This motor will be in a full size '71 Bonneville with stock rebuilt TH400 w/stock stall speed converter and 2.73 highway gears. The emphasis should be on low end torque, but with a touch of top end to throw in. I will mostly cruise this car around, but I want some extra power underfoot to *ahem* educate some foolish youngsters in Hondas, and every so often take it to the track. This car's performance in stock form was not terrific, perhaps in the 16's in the quarter, and I'd like to touch on the edge of the 14's if possible. I understand this may be slightly unrealistic, but either way, I want to make as much power as I can get, while still keeping that smooth idle. No major lope for me!

Here's my basic combo up to this point:
Stock 455 block, standard bore with flat top forged pistons
6X-8 heads, mild port cleanup with gasket match and stainless valves
Stock late 60's Pontiac 4bbl intake
Probably using a Rochester Quadrajet
MUST use stock exhaust manifolds
Ignition undecided - Was running a Pertronix unit in my stock distributor for years before, but may upgrade to an MSD setup, not sure yet - Thoughts?

So, good people, what say you? What camshaft kit and valvesprings would you use for this combination, for what I want to do?

[screamingchief]

Much of that is absolutely do-able,but IMO it's kinda gonna be a challenge to do it with that strict 87 octane only requirement.

A 455 with flat tops and 100 cc heads is gonna be like 9.0:1 or just a tic over that.

And then throw in the fact that many high performance type cams will typically end up making more cylinder pressure,and things can end up headed towards risky territory in a big heavy car with a stock converter and 2.73 gears.

And doing something like throwing in a cam that might help the cylinder pressure situation,well that can often end up being a hit-or-miss match to the rest of the drivetrain,so one has to choose a cam like this very,very carefully.

Tough call if you ask me???

Combos like this are often somewhat harder to plan & sort out than the "hotter" combos are.

Most here will likely recommend something like the SD "stump puller" HR cam.

Honestly,,,I dunno what I'd really recommend here,,,I dont really build my stuff like this very much at all anymore...

If it were my car/build,I'd almost certainly be looking long and hard @ the various lobe catalogs,and then ordering a custom ground HR cam.

And I'd probably knock the CR back down to like 8.5:1 to 8.75:1 max to manage that 87 octane requirement.

Though I'm sure some here will debate that advice.

But IMO a .25 to .5 point of CR wont "make or break" a combo like that in terms of it's ultimate performance,but I feel it should buy some leeway in the cam selection choices here,and it almost certainly would'nt hurt the goal to run this strictly on the 87 octane either.

Anyhow,it'll be interesting to see what sorta recommendations you get on this.

Crane used to have some nice smaller HR profiles that would be probably pretty good for a combo like this,I'll have to check my old Crane cam cards for those grinds and get back to you.

Bret P.

[Tim john]

Well here is your fist vote for the SD Performance "Stump Puller" grind if you have decent exhaust such as H.O. manifolds and free flowing pipes of say like2 1/4 - 2 1/2" and better than stock original heads flowing in the 250ish cfm range. As I mentioned sevral times in the past I would suggest calling Dave and or Marcel at SD Performance for their advice, well worth your time to make the call.

Tim john---

[cnc]

I run the Stump puller as suggested from Dave and Marcel build is in the sig below....

[Cliff R]

Pretty big cam for a stock converter and those gears, but IMHO, it would be fine otherwise. I would upgrade the converter to our Continental 13" unit. You will never know it's there till you need it. We've sold them to folks with full size cars and gear ratios as low as 2.56. It will drive just like a stock converter, but allow the engine to rev into it's good power range on heavy/full throttle starts.

When you get in a grudge match with a fart-piped Neon or Import, you will really be glad you did the upgrade!.......Cliff

[PONTIAC DUDE]

My Butcher special hydraulic roller. Need to know actual compression ratio, converter & rear gear before i get into LSA & CL's.

[Fullsize455]

Thanks for all the replies. I'll address them all in one response, with Cliff's notes below:

My compression ratio will be 8.8:1 compression with the stock thickness head gaskets I will be using. I said "flat top" pistons, though I suppose I should have said "flat tops with valve reliefs". Either way, actual compression ratio will be 8.8:1.

I don't mind having to put 91 octane in it when I head to the track on certain occasions, or if I know I will be going up the Grapevine in 100 degree heat, but I do want to run 87 octane for most of my regular street driving. I don't want to build an engine that may not run well in the future when gas gets even crappier. I'm fine with the compromise for now. I don't have lofty or specific goals, I just want to make as much power as I can with what I've got.

I am adamant about keeping my 2.73s in the rearend. I intend to do a lot of freeway driving and don't want the decrease in fuel mileage or sustained higher RPM operation that steeper gears will result in. I also do not want to install a 700R4 or other overdrive transmission, as my TH400 is alive and well, and is a great transmission that shifts EXACTLY how I want it to, and I am so damn picky when it comes to stuff like that, I don't want to mess with a good thing. Anyway. Sorry for my long winded posts!

As far as installing a different converter, I am not completely opposed to installing a different converter, but I am adamant about not wanting a converter that will require higher RPM low-speed starts, the way that higher stall speed converters do. Perhaps I'm not articulating that well, but I assume you know what I mean. I want this car to drive as stock, with stock, very mild manners in day to day street driving, where anyone and everyone will assume it is stock, until I put my foot down. That's as much for the sleeper effect as it is for my daily enjoyment of the car. I don't want to drive a car that will jump right up to 2200rpm+ with 1/4 throttle at every stop light.

As far as exhaust, I will be using my stock '71 manifolds - I don't know if they're considered HO manifolds or not - They are what came stock on my 280hp 2bbl 455 with 98 heads. They look like a decent manifold, better than some that I have seen, but they are definitely not Ram Airs or anything close to it. Behind that I have 2 1/4" dual exhaust with a crossover pipe, with mufflers taken off a stock '96 Impala, no resonators. I LOVE the sound of this car with these and won't be changing them or the pipe size.

What I want to end up with is a very drivable car, with a responsive engine that makes good, solid low end torque, and decent top end power. I'm not going to be pushing it past 4500 rpm EVER, so any power above that point is wasted. I'm building this engine to last me the next 20-30 years, and fully intend to put 200k miles on it or more in that time, so reliability is paramount, with good power and drivability. I have always liked the way that Pontiac V8s run, and even in stock, low compression form, this 455 was very responsive considering. I'm comparing it to a '72 Lincoln 460 that I had that was just LAZY in comparison, as well as a 402 big block Chevy that was also somewhat disappointing, especially for how much fuel it used! This 455 was always fairly good on fuel consumption for the 50k miles I put on it prior to starting this build. I don't expect that mileage to be the same when I'm done, but with 240k miles it was still getting 16mpg on the freeway going 65mph, so I'm hoping to get at least 14 freeways miles per gallon or so with this combo. I guess we'll see!

Thanks a bunch for the advice. I don't rush into any decisions, and it will still be several weeks before I have all the parts to build it, so there's no big rush. I'd rather do it right than do it twice, you know? This will be a highly detailed semi-show car when it's completed, and I will NOT want to tear this engine apart once it's painted nicely and detailed, so once it's done, it's done.

Also, I will be running stock valve covers on it, but I would like to upgrade from the stock stamped rockers to something a little better - Any recommendations on a rocker that fits under stock valve covers? Perhaps a stamped, roller-tip rocker? Thanks all!

Cliffs:
8.8:1 compression
Stock non-RA exhaust manifolds
2.73 gears
Stock converter or aftermarket that acts as stock
dual 2 1/4" exhaust with crossover
6X-8 heads with 2.11/1.66 valves, mild port job and gasket match
Standard bore 455 with flat top pistons with valve reliefs
Stock 4bbl intake and probable Rochester Quadrajet
Intend to drive this EVERY day and put 200k miles on it

[Silver Judge]

SD Performance's Stump Puller is probably too much cam here
Same thing goes for the SD Performance "road paver" cam

SD Performance can sure suggest an alternative, they spec cams out for all sorts of things, 455 powered haulers, hill climb race cars, etc.

[Steve C.]

Hydraulic Roller Cam 270/278
[email protected] 222/230 [email protected] 560/560 LC 112


At todays prices around here it's about .24 cents differance between regular and premium. Based on 200,000 miles over 20 years at 14 mpg it wouldn't have much impact on the wallet for the differance. But then who knows about gas in 20 years !

[Fullsize455]

Originally Posted by Steve C.

Hydraulic Roller Cam 270/278
[email protected] 222/230 [email protected] 560/560 LC 112


At todays prices around here it's about .24 cents differance between regular and premium. Based on 200,000 miles over 20 years at 14 mpg it wouldn't have much impact on the wallet for the differance. But then who knows about gas in 20 years !

Well it's more about the availability of fuels in the future that I worry about than final cost. That said, my calculations, based on a 30 cent difference, which it usually is here, and an overall average of 12mpg(I hope to get 14 on the freeway, I won't get that around town), indicate that I'd probably spend an extra $5k on fuel over 200k miles. Again, that's not that big a deal, and I'm not going to sacrifice all hope of performance for that, but I know that 87 octane should be fine for most use underneath 9:1. My 10:1 383 4bbl in my '66 Chrysler even runs fine on 87, at the stock timing spec, so I know this thing should be just fine at 8.8:1. If it's not, I'll deal with it and put higher octane fuel in it, but I doubt I will need to.

The cam specs you give above.. How will idle quality be with that cam? Having thought this through in my head based on past builds, that does seem very much in line with what I was thinking, but extra opinions never hurt. Is that a specific grind you're aware of by a certain manufacture? Any more information? Thanks!

[Fullsize455]

What do you guys think about using these rockers? http://www.summitracing.com/parts/CCA-1451-16/?rtype=10

Keep in mind that I'm going to keep my stock valve covers, and don't want to use spacers under them either. Is the best that will fit underneath them?

[Steve C.]

Crower has a hyd flat tappet with similar specs and it's well touted. I've seen it suggested for similar situations over the years. Being a roller the tappet duration will be differant and it will have additional lobe lift. Comparing the two types, even with the same duration and lobe separation, you're picking up more hp and tq across the entire rpm range. Driveability typically improves with a roller. Crower states the rpm range for the HFT cam as 2000-4800 in a 455.

Regarding brands, I personaly have no experiance with a hyd roller cam. But I would highly recommend it be a custom, not from a shelf at a wharehouse. A Comp lobe, Ultradyne lobe, Isky lobe would probably be easier to obtain than a custom Crower Hyd roller. But that's just a hunch. Any "Pontiac" dealer can have one made.

[Cliff R]

I agree with Steve's cam recomendation, 230 @ .050" in a roller is gonna be a tad too much at 8.8 to 1 SCR in this application.

The 13" converter we sell is PERFECT for cars like yours. One of our customers tows a boat with his full size car and a 13" converter. They are very efficient, but still allow more stall speed than a stock converter when hit with full power. They are not "loose" anyplace, and locked near solid above the stall speed.

It will be the second best decision made here next to the hydraulic roller cam upgrade, IMHO.....Cliff

[BVR421]

"but I am adamant about not wanting a converter that will require higher RPM low-speed starts, the way that higher stall speed converters do"

where are you getting these ideas LOL

the 5500 rpm stall converter in my race car doesnt do that why would a street converter?

[Cliff R]

Folks just don't understand how converters really work. It's a fluid coupling, so without a clutch inside of it, they all have some slippage, even stock ones. When folks see someone mentioning 3200rpms stall speed (for example), they think it takes at or near that rpm to move the vehicle. Some have also had associations with cheap "shelf" converters that are extremely "loose" everyplace, and never do couple worth a crap at any rpm.

A good street converter will act and drive just like a stock unit, yet allow the engine to see some additional rpm's with good traction when hit with full power, over a stock type converter.

Even my 10" unit would work fine in a heavy car with a low (numerical) axle ratio. It move the car right off idle, and doesn't flash up at light load in any gear.

Load stalling it holding the brakes it will overcome the tires at 1900rpm's.

Any heavy throttle in high gear at low vehicle speeds, like climbing a steep grade, the engine will see about 2200-2400rpm's.

At the track with perfect traction, it flashes to apprx 3500rpm's, enough to put my daily driven car DEEP into the 11's in full street trim.

The 13" Continental unit nearly as good as the 10" unit. My old 455 would send one to just over 3000rpm's at the track, it was every bit as tight at every level as the stock converter it replaced otherwise. I couldn't get the engine much past 1700rpm's on the brakes, and about 2000-2200 loading it pretty heavy on the street for passing situations, climbing steep grades, etc. It ran nearly as quick in 60' times as the 10" unit that replaced it!

I mentioned it in association with this thread based on the goal(s) of the vehicle. The converter would be the best place to spend money, especially with this application, where the owner wants to keep most things pretty stock/mild, and still the ability to unleash the big 455 torque when it's needed.

We just helped two customers with very similiar set-ups, one replaced an early 4 speed auto with one of our TH400's. We installed a low 1st gear set, and 13" Continental converter, backed by his 2.56 axle ratio. He now has big car that drives great, gets good fuel economy, and launches hard with a little traction!........Cliff

[taalltheway]

Hmmmmm...this is a very tough nut to crack...

....you want more power but you want to keep ecerything like it is. Your car does act like it does because it is built like it is. If you change something towards more power it will feel a bit different. Well, let me try:

More power usually comes from more compression, larger cams, better intakes, better exhaust and better airflow in the engine.

More compression is out of the question - OK, i even think that is a good decision in a streetbuild.

To keep that engine idling with near stock quality you will need a cam under or at least no higher than 220 degrees duration @0,050....even as a rollercam. If it was a hydraulic cam i would recommend to play with Rhoadslifters but you have ruled this out.

Where you could really get some more power would be to invest in better exhaust RA-manifolds or even -god forbid - headers!

Another big point is the airflow: i would have a real specialist port and polish the heads and portsmatch the intake in the best possible way.

With the better exhaust and maximum airflow with your limited powerband you get at least the best possible.

If you just keep your heads as they are; your intake and carb as they are; the exhaust manifolds as they are then only the little bit hotter camshaft will definetely not make a night and day difference....

If you want noticably more power you need to bite the bullet and at least dump the manifolds, accept a little bit lopey idle and have the heads completey reworked by a Pro!

If not just have a stock rebuild with stock results and be happy with it.

[Steve C.]

Good example of a 455 street engine with a hyd flat tappet, just change it to a similar hyd roller cam.
Stated- "This is a fairly mild working daily driver combination, making approx. 425 hp, in a car that can run 12.40's with stock type suspension, a/c & weighing 3800 lbs."

Too much duration ?? I don't think so !

Camshaft: Comp Cams #XE 268H Hydraulic cam and lifters(this cam works from 1500 to 5500). 224/230 duration @ .050, Lift:.520 intake/.524 exhaust, with 1.6 rockers: advance cam 2 degrees.

http://www.angelfire.com/fl4/pontiac...nebuildup.html


455 Engine Build - New-Age Super Duty
Cam: Comp Cams hydraulic-roller, PN K-51-423-9
Duration at 0.050: 224/230-deg
Lift: 0.552/0.561
Lobe Separation Angle: 110-deg
http://www.highperformancepontiac.co...ild/specs.html

[Steve C.]

210-225 Intake lobe duration @ .050" lift

Daily Driver, Street Performer or Weekender- YES

And this is based on a hyd flat tappet cam not a hyd roller which has the potential for better performance and driveability.

http://www.pontiacstreetperformance....camselect.html

[Fullsize455]

Originally Posted by BVR421

"but I am adamant about not wanting a converter that will require higher RPM low-speed starts, the way that higher stall speed converters do"

where are you getting these ideas LOL

the 5500 rpm stall converter in my race car doesnt do that why would a street converter?

Because I've driven more than a few cars with 2400-ish stall speed converters that will roll backwards on the slightest incline when in gear and require noticable(IE too much) throttle input to move the car at all from a stand still, that's where. I'm glad you think it's funny, but it's not at all.

Edit: And having heard MANY cars equipped with higher stall speed converters as they accelerate from stoplights and such, and the rpm jumps way up higher than it would with a stock converter. I want no part of that. Perhaps it's a matter of cheap converter vs. good, high quality converter, and I have no problem spending money on good parts, but I want daily driver manners, in a sleeper package that looks stock on the outside and under the hood, with the only way to know any different being to look at head casting numbers.

It's amazing that so many people don't understand where this quest comes from. I guess some of you have never heard of the Factory Appearing Stock Tire drag races? It's the same concept, only much more mild. Read:

"No matter how you look at them, F.A.S.T. cars appear showroom stock, including the body, interior, engine and all its external components & manifolds, even the wheels and original 1960's style skinny bias ply tires. As a matter of fact, F.A.S.T cars place very well at shows for "restored" cars, and even sound stock at idle.

But get a group of them on the drag strip, and LOOK OUT! You will see F.A.S.T. cars covering the 1/4 mile in 13, 12, 11 and some even in the 10 second range, with the fastest cars posting trap speeds of over 130 MPH! You see, F.A.S.T. cars may look and sound stock, but internal engine modifications are not restricted."

The point is, there is a middle ground between being bone stock and making gobs and gobs of power with headers and all kinds of other high-visibility modifications. Again, I want to make the most power that I can while still retaining the appearance and manners of stock. Difficult? Yes, absolutely, but that is why it must be done. No, I won't be running in the FAST races - I'm not THAT serious - I just want to make a bit more power, that's all.

It has nothing to do with being a cheapskate or wanting to skimp on parts here and there, and everything to do with the true concept of a sleeper. Yes, it is a compromise - I understand that. I'm ok with that. But at the end of the day, the 350 or so horses I should be able to make and 450+ foot pounds will still be a HELL of a lot more than I was making before.

It's amazing to me that some people simply want all or nothing, and don't understand someone having a different goal than yourself. It's not my intention to start an argument or cause trouble or otherwise stir up crap, but seriously guys, accept that some people have different goals and try to understand why they might not be the same as yours.

Bottom line: I want to make the most power that I can with what I have - That's all. As I have made clear, I have no set goal, and won't be disappointed with the result, regardless, because at the end of the day, no matter what I do, I will be making a lot more than I was making before. Period.

If these guys running the FAST races with Hemi Roadrunners on skinny bias plies can dip into the 10s when their cars were in the 13s stock, surely I can make a few more horsepower than I did before while still appearing stock. That's the entire point, the heart of my goal. Nothing more.

[Fullsize455]

Originally Posted by Cliff R

I agree with Steve's cam recomendation, 230 @ .050" in a roller is gonna be a tad too much at 8.8 to 1 SCR in this application.

The 13" converter we sell is PERFECT for cars like yours. One of our customers tows a boat with his full size car and a 13" converter. They are very efficient, but still allow more stall speed than a stock converter when hit with full power. They are not "loose" anyplace, and locked near solid above the stall speed.

It will be the second best decision made here next to the hydraulic roller cam upgrade, IMHO.....Cliff

How much does that converter cost?