[Cliff R]

Nunzi 2041 288 302 222 232 .450 .460 113 69
H-O Ent. HC-01A 276 288 222 232 .470 .490 109
Crane H-278-2 278 290 222 234 .470 .490 114 56
Ultradyne - 280 288 223 231 .460 .490 110 Great street performance
Indian Adventures - 282 282 224 228 .470 .480 112
Comp. Cams XE268H 268 280 224 230 .480 .480 110 50
Edelbrock 5057 298 304 224 234 .470 .490 114
H-O Ent. 380k 290 300 224 234 .470 .490 117
Speed-Pro 1175 - - 224 234 .470 .490 112
Summit K2802 282 292 224 234 .470 .490 114 59
Wolverine WG1096 290 300 224 234 .470 .490 112

Aside from the Comp XE 268, all of these camshafts are very close, and a good choice for a 400cid engine with high compression heads and well chosen gearing/converter......Cliff

[ponyakr]

When I 1st saw the specs on the "steep ramp" cams like XE and Voodoo, it reminded me of the what we called the NHRA "cheater cams". We ran both the 067 and 068, in a Lunati brand. Obviously the cam grinders get together with NHRA and find out exactly how much cam they can get by with, and still pass tech for a particular factory cam. The NHRA rules I read listed only vague specs, which included a lift that was slightly higher than factory. So, I assumed that the cam grinders would leave as much lobe as possible which would pass tech and which the hyd lifters could follow.

As soon as you crank your Stocker engine with one of these cheaters in it, you know it ain't even close to stock. That's just one of the things that allows the Stockers to go so fast. Stockers that run this cam today are running 10's. I've wondered if these Stocker grinds are where they came up with the idea for these steep ramp cams offered today.

For many of the shelf cams, you can get the exact specs on the lobes. But I assume that because of competition between Brands, they would not wanna publish the specs on the Stocker cams. But since this thread is about the 068 cam, and some have mentioned that the duplicates are not exact duplicates, I'd like to see the lobe specs on some of these Stocker 068 cams, as well as the duplicates, to see just how much different they are from the factory 068.

[rohrt]

Originally Posted by b-man

These are simply advertised horsepower ratings that you must take with a grain of salt.

Quite often the top rating is not to exceed 10 pounds of vehicle weight per HP. Note the Firebird vs GTO ratings for the same exact engine, Firebird being lower because of the lower vehicle weight.

Wasn't there a limiting tab on the Q-jet that reduced the HP on the Firebird? It may explain that example but not all the others.

[Formulajones]

The NHRA stock and super stock rules leave alot of loop holes in the camshaft selection. Although they are pretty strict on lift values, you are allowed to play with duration and LSA as much as you want, which is why those engines, even though are touted to have stock lift camshafts, still sound like a pro stock engine, because they are running a ton of overlap and duration where the rules are laxed. That's why they spin alot of rpm and make HP.

The pure stock and factory stock racing (if you pay attention to that sort of thing) have taken some of this thinking and applied it to their stock engines. Rules dictate that completely stock camshafts must be used, however I know of a few people that are running what many in the circle refer to as "cheater cams". They have played around with duration and LSA numbers a bit for more lift under the curve. Might only mean a few HP here and there but these guys are serious about making the most out of a combo. Now where you install the cam (ICL) is any bodies game and no rules dictating that. But these classes are much more indicative of what a particular "stock" combination is capable of.

[68azbird]

The 744 ran better than all the other junk cams at the time in a .030 over 400 with stock unported heads in a 80 TA. Engine pulled all the way up to 5500 with a performer RPM 850 holley DP

[Matt Meaney]

Originally Posted by PONTIAC-ONE

69 428 made 390 hp
70 455 made 370 hp

Is this fairly accurate? 428 had a little more compression but I would think the 455 would out power the smaller engine....

maybe the 428 having the long branch manifolds and the 455 having the logs, plays into it as well.

[geeteeohguy]

rohrt, yes, you are correct about the limiting tab. At least in '67 and '68.

[b-man]

Originally Posted by geeteeohguy

rohrt, yes, you are correct about the limiting tab. At least in '67 and '68.

From what I understand after that time the carbs were no longer different. One example would be the 1970 RAIV rated at 370 HP in the A-body and 345 in the F-body.

By 1971 the horsepower ratings were the same for both A and F-body cars, so it's mostly a numbers game and not really based on actual output in every instance.

How about the '63 421 Super Duty rated at 405 HP? Easily a 500 HP engine, factory HP numbers were advertised to suit each particular situation.

[77 TRASHCAN]

69 firebird had carb linkage derated, also...

One of my fellow Ponitac enthusiast's bought a 69 FB, new coming home from Viet Nam. He knew nothing of the "factory" carb adjustment. He just checked for full throttle after having driven car for a while, made the "repair"

I'm thinking about looking through some of my parts catalogs to see of there's a SBC cam w/ similar spec's...Sounds like it'd work great in a 406 SBC...

[Will]

Originally Posted by b-man

From what I understand after that time the carbs were no longer different. One example would be the 1970 RAIV rated at 370 HP in the A-body and 345 in the F-body.

By 1971 the horsepower ratings were the same for both A and F-body cars, so it's mostly a numbers game and not really based on actual output in every instance.

^^This^^

Horsepower ratings were more marketing than reality in the '60s. GM had an unspoken rule about horsepower/weight ratios so the same engine would be rated differently in one car than in the other.

Lots of ways to fudge the numbers. Easiest is to look at the RPMs at which they were rated. Engine 'X' produces 360 hp @ 5200 RPM in one car and only 345 hp @ 5000 RPM in in another. Exact same engine, just the numbers taken at different RPMs. Neither is claiming that's the peak HP that engine made, either...

Hard to believe the RAIV with all the tricks the engineers threw into that engine didn't make more HP than the 428 HO. Pretty sure it actually did, just was way underrated.

[TedRamAirII]

Originally Posted by rohrt

Wasn't there a limiting tab on the Q-jet that reduced the HP on the Firebird? It may explain that example but not all the others.

Yes, there was a tab to limit throttle opening. Plus I think it was just a "inside rule" that stated "No engine will have more HP than the GTO", Just like Chevrolet's "No engine shall have more HP than the Corvette" ; )

[Will]

Originally Posted by PONTIAC-ONE

69 428 made 390 hp
70 455 made 370 hp

Is this fairly accurate? 428 had a little more compression but I would think the 455 would out power the smaller engine....

Originally Posted by Matt Meaney

maybe the 428 having the long branch manifolds and the 455 having the logs, plays into it as well.

A larger displacement doesn't make more horsepower (all else being equal), it makes more torque but at a lower RPM.

Build a 400 and a 455 with all the same parts to all the same specs (CR, head airflow, etc) and they will both make the same HP but the 400 will make it at a higher RPM. The 400 will have a lower peak torque value but that peak will occur at a higher RPM.

In fact, given there is a roughly 15% difference in displacement, the 455 will make right about 15% more torque at 15% lower RPM.

Cool, huh?

[b-man]

Okay, let's get

I used to drive daily a low-compression 1974 455 running the 068 cam (Crane 'Blueprint' version) with stamped-steel RAIV 1.65:1 rocker arms. It had stock 1971 #66 455 heads (114cc chambers, 2.11/1.77 valves, converted to screw-in studs) and +.030" flat-top TRW forged pistons on stock cast rods.

Compression calculated out to 8.2:1. The pistons were at zero deck to -.005" in the hole, just like all of the untouched 455s I've torn down. Topped it off with a stock '66 Tri-Power and used a set of reproduction '67 HO/RA exhaust manifolds along with a 2-1/2" mandrel bent exhaust. Ignition system consisted of a stock points distributor (H-O Racing curve kit) with a stock coil.

The rest of the drivetrain consisted of a 13" Continental converter, TH400 trans, a 2.56 open rear and 235/45-17 tires (25.3" tall). Installed in a '64 Tempest that weighed 4150 with driver it cranked off a 13.899 @ 101.85 MPH in the 1/4 mile with a very soft 2.3-second 60' time. It went through the traps at the end of the track at the top of 2nd gear.

Didn't set the world on fire, but it had a 140 MPH top end and was very easy to drive daily. Always fired right up on the first crank and ran well on cold winter mornings, the intake manifold heat risers were not blocked and choke was fully functional.

With a posi unit and good traction tires this car should have been able to get into the mid to low-13s, but it was built on a budget as a highway flyer keeping the original 10-bolt 2.56 open rear. I was pretty happy with the performance of this low-compression 455 using all stock or repro Pontiac parts with no mods, trapping at nearly 102 MPH is pretty good for the ol' 068 I'd say.

[phil400]

Does anyone know why the 71-72 455HO engines used the 068, and 73-74 455 SD engines used the 744?
Both engines had the same comp ratio and similar head flow, yet with less cam the HO's had a higher HP rating.

[b-man]

The 455 SD engines were originally slated to use the 041 cam but wouldn't pass emissions testing, please correct me if I'm wrong.

The 455 SD heads are superior to the 455 HO heads, with a bigger cam and better heads rating the 455 SD at 290 HP and the 455 HO at 335 and 300 respectively doesn't really make a lot of sense to muscle car fans.

Breakdown of the some of the main differences between 455 SD and 455 HO heads: http://forums.maxperformanceinc.com/...41&postcount=9

Again the factory horsepower ratings are just numbers, not reality.

Sometimes the stronger engines were rated lower, you must keep in mind these were difficult times for the automakers with the feds bringing the hammer down hard on emissions. We were lucky to see the 455 HO and SD engines going into production, after 1974 big-cube performance was all over with.

[phil400]

Cool thanks, I never knew the SD heads were that much better than the HO heads, I thought since they were both round ports they were pretty much the same.

[b-man]

My brother had a fairly fresh 1968 +.030 350 that came in a '68 Firebird that he bought. We decided to install in his heavily-optioned 1969 265 HP 2-barrel/TH400 350 Firebird after replacing the top end components.

The '68 350 had a mis-matched set of heads, one was a '68 #17 head and the other was a '69 #47. Both heads had sunken valve seats from too many valve grinds so they were set aside. I donated a pair of 1969 #46 heads leftover from a 360 HP Bonneville 428 - 1.96/1.66 valves, 72cc chambers and press-in rocker studs. Compression ratio calculates to right around 9:1.

We installed the 068 cam (sourced from Warrior Racing many years ago) and advanced it by 4 degrees using a Cloyes Tru-Roller timing set. The stock valve springs were retained along with the factory stamped 1.5:1 rockers. The stock press-in rocker studs were retained and the rocker arm nuts were simply torqued down to the factory 20# torque setting.

The 350 (actually now a 360 at +.030) was topped off with a '69 iron Q-jet intake and a '72 750 CFM Q-jet I found on a '72 400 at the local Pick-Your-Part yard, rebuilt by Brad Urban's Carb Shop. The exhaust crossover in the intake manifold was not blocked. Exhaust was handled by stock log exhaust manifolds and a 2-1/4" dual exhaust.

Drivetrain consisted of a TCI Saturday Night Special converter (2500 stall?), TH400 and a 3.42 geared 8.5 10-bolt posi rear (pirated from an '80 T/A after relocating the spring perches) and 235/60-15 radial tires.

This fully-loaded '69 Firebird weighs in at 3700# plus and is equipped with a power driver's seat, power windows, deluxe interior, factory A/C, power steering and power front disc brakes. At a race weight close to 4000# it went 14.79 @ 95 MPH, launching easy to keep traction.

All in all a good running budget 350 using all stock components.

[b-man]

Link to another thread discussing the 068 cam: http://forums.maxperformanceinc.com/...d.php?t=751422

Happy New Year 2015!

[steve25]

I will look to see if I still have the mag from the early 90s , but I think it was muscle car mag where they rebuilt to stock specs a RA4 400 and a RAIII 400 and did a 3 pull Dyno session with each motor through there stock exh manifolds and if I recall right they powered no alternator, but did drive the watter pump.
The result was that the both motors bested the factory ratings, the 4 Motor made 400 hp and the 3 motor made 370 hp , so not too shabby by any means!

[Cliff R]

The 71-72 HO and 73-74 Super Duty engines should have got the RAIV cam, at least in the 4 speed applications. They would have been even better with Rhoad's lifters as far as getting thru emissions. Those engines have great potential, even at the low compression ratios they had at that time. We've easily made over 1hp/cid with them using well selected HR camshafts. With a little head porting and squeezing them a little harder, they quickly jump up into the 480-500hp range, and 540-560tq. I've never dyno's a stock one, but bet they are under 400hp and not much over 520tq.

As far as the early FB q-jets, they used a limited opening for the secondary throttle plates, and they also used a longer stop on the secondary airflap than other Ram Air q-jets used at that time. A few minutes work in both places and they are right on par with any other Ram Air carb and a nice wake up call for your early FB engine......Cliff