[77 TRASHCAN]

OK, Rocky, where are you? Tell us!!!

A smallish cam in a 500 cublic inch engine (that already has mega torque engineered in, via cylinder head design...) for MORE low end power.......HUH?

[Steve C.]

Keep in mind it has fuel injection installed on the car after the dyno session. It will support the cubic inches/ cruise rpm requirements on the 495.

Here was Rocky's write up on the previous combo:

http://www.hotrod.com/articles/hppp-...ection-system/

Part II

http://www.hotrod.com/articles/ez-ef...ection-system/





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[gtofreek]

No need for the 4.5" arm IMO. The 468 I just did with iron D-port heads and HO manifolds made 580 ft. lbs. at something like 3700-3800 rpm, and still made 521 HP below 5500 RPM. Made somewhere in the mid 400's on torque at just 1600 RPM. All this with 1 point less compression. That thing was a torque beast, and would outrun this 496 I bet.

[Steve C.]

"...but we simply couldn’t resist stabbing the accelerator to feel the immediate responsiveness..."

It's going to be a fun adventure. Note the tires and unknown suspension from the pictures. Just a guess, but consider they are rock hard BF Goodrich 245/60-15 tires. Out at 60 mph, cruising on the open highway in the country at 2700 rpm. Not factoring in his way tight converter. Now he decides to 'stab' the accelerator for a quick jaunt up to 100 mph, without blowing off the tires. Lifting at 100 mph with the convertible top down and cheeks puckering, all four of them, it's still about 500 rpm less than where it makes peak power.

Side topic- keep in mind his restrictive exhaust system.

[pastry_chef]

Originally Posted by dmac

Torque at lower rpms is a lot of fun when geared right. Makes jumping from 60 to 80 mph to pass a truck a breeze for those who really drive their cars. I'm working out how to build a motor with max torque at even lower rpm, right in the 2000-2500 rpm range, actually with 2.56 gears for a daily driver. Keeping rpms lower should help it live longer. Going from 60 to 80 mph is more important than 0-60 to me, even if it takes me two miles to get up to max speed.

The term "torque" is overused and widely misunderstood.

Tractive Effort (pounds of force to the drive tire) can be narrowed to just four controlling variables:
Cylinder pressure, Bore area, Piston speed and Wheel speed.

For a set RPM or RPM range, piston speed can be increased by using longer stroke.
Bore area is obvious.

On designing induction and valve timing to maximize cylinder pressure at only 2500 RPM.
In 99 % of cases such an engine would lose BADLY to a same bore size engine that uses more piston speed (higher RPM with matched gear).

[Steve C.]

Of interest, another 4.500 stroke low rpm street build. Not to detract from Rocky's 495 CID build but to aid as a comparison for conversation.

Note it used a rated "850 cfm" carburetor, however at peak power the SCFM was a lower 622. And a larger 236 degree hydraulic roller cam in use. Also note the power band of Rocky's 495 CID engine is wider in the range of operating speeds under which the engine is able to operate efficiently. A 1400 rpm spread between peak torque RPM and peak power RPM. Whereas the 501 CID engine as presented here has a narrow 800 RPM spread. However it was reported they didn’t have the luxury of spending additional dyno time for fine tuning or experimentation.

Max power was recorded at 525.4 HP at 4900 rpm, and max torque was 604.8 lb-ft at 4100 rpm. SCFM at max HP was 622.

In short:

455 block

4.210 bore

4.500 stroke

6.7 rods

Ported KRE d-port heads

Comp XR288HR 236/242-110

Hurricane single-plane intake

Holley 850 cfm Ultra XP carburetor

Hooker Super Comp headers, 1.750” primary tubes and 3” collectors.

https://theshopmag.com/features/pontiac-501-dyno-run



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[Cliff R]

Several year ago we supplied a custom built Q-jet for a 455 build that used Dave's Old Faithful camshaft, KRE heads, ported RPM intake, no spacer. The compression ratio was just over 10 to 1. That engine was dyno'd elsewhere so we didn't have any hand in it besides supplying the carburetor. It made 552hp/604tq. Torque was over 500ft lbs from 3000rpm's to nearly 5500rpms and over 550ft lbs across most of the mid-range, making peak torque around 4200rpm's nearly as I can remember.

The results of that build stick strongly in my memory (as do a few others) because the shop doing the testing couldn't believe a factory late model Q-jet could support that kind of power.

Nothing wrong with the build in question focusing on smooth idle and putting power low in the rpm range, but it makes me wonder if it will be able to effectively manage a steady diet of pump gas as dynamic cylinder pressure at low rpm's is going to be off the scale......IMHO......Cliff

[Rocky Rotella]

Steve, I appreciate you bringing light to the engine article. Thanks!

And thanks for all the comments guys. The build was very specific, and max HP was truly the last concern.

My cousin, Lou Rotella owns the ’67 Firebird convertible that this engine was built for. He owns a number of high-end late-model performance cars and bought this particular ’67 Firebird around 2000 to fulfill the memory of the ’67 Firebird 400 that he purchased new. It was a rust-free California car that was completely original save for a repaint.

Several years back we removed the original 400 (with AIR) and installed 455 (bored .030” to 462-ci) with mildly-ported 4X heads and a 232/243-degree camshaft. I modified a late-70s QJ with Cliff’s help and it ran relatively well for as truly mild of a combination as it was. The Turbo-400 was rebuilt and received a 13” Continental converter that stalls to approximately 2,500 rpm. The original 3.36:1 limited slip axle remains.

At 68 years old, Lou doesn’t race his cars. He typically doesn’t even drive them hard either. He simply likes to take one out for a cruise and maybe run it through the gears if he gets the urge. Accustomed to the way his new performance cars startup and operate in all conditions cold or warm, he discussed with me ways to make his Firebird more user-friendly.

The 455’s QJ was equipped with a functional electric choke, but with today’s fuel and as quickly as it evaporates, the engine had to crank several times to draw fuel before it would start and there was some warmup time required. I looked into available fuel injection kits and found FAST’s EZ-EFI a very suitable alternative. It installed easily and performs flawlessly. All of the operational advantages are discussed in the stories I wrote for HPP that Steve provided links to.

Fast forward to earlier this year. Lou was having some detail work tended to by T&M Automotive in Omaha and it necessitated removing the 455. The engine needed a rear main seal anyway, so they decided to freshen up the bottom end. Willard Auto Machine (or WAM) in Omaha handled that. During the process they (all three parties, collectively) elected for a complete rebuild, increasing displacement and adding modern cylinder heads was part of the process.

WAM has built a number of Pontiacs that have performed exceptionally well. WAM spec’d all the components based on what Lou wanted to do with the car. He sought a maintenance-free, pump-gas combination that starts up quickly and easily, idles smooth without shaking, produces plenty of vacuum for power brakes, drives exceptionally well off-idle and low-speed, and can spin the tires hard when he stabs the throttle and accelerates hard when he kicks it down a gear at speed. It’s really all about the feel for him.

I learned from WAM the build details during the process and thought it was very reasonable for the intended application. Knowing that CID adds drivability overall and long-stroke adds torque, I’d say that the combination does exactly what it was intended to. WAM would have preferred the round-port Edelbrock heads for this particular build but since the car already had well-fitting d-port headers, D-ports were really the only choice.

When I saw the numbers come in at 594 ft/lbs, I was very happy for Lou because we can all imagine what it has feel like, and with 19-inches of vacuum at idle, I knew he’d be very satisfied with the result.

As for the 650-cfm carb, WAM says that he has a Holley HP that is his go-to dyno carb because he knows it performs well. Since the EFI system was already in the car, it wasn’t practical to remove it simply for the dyno test. In fact, the dyno session wasn’t intended to tune for max power. The EFI’s PCM will handle that. Instead, it was simply to make sure that the 495 pulled smoothly and cleanly throughout the engine’s operating range and made reasonable power, and was leak free before turning it over to the customer.

I was discussing with John McGann at Car Craft the build details and the result. He felt that it would be a great opportunity to provide readers with Pontiac V-8 material and draw attention toward what our beloved engines do best. I’d love to throw some slicks on it and make a pass or two down the drag strip, but I fear that the long-arm Pontiac V-8 and near-600 ft-lbs would twist that Firebird convertible chassis into a pretzel!

In the end, Lou is totally unconcerned with power past 5,000 rpm. It’s just not the car to run max out in every time. This is a car he occasionally cruises in with the top down. Considering that this wasn’t a max-HP build, there are several areas that would probably have been better chosen that would have increased that, but the fact remains that this 495 does exactly what its owner wanted it to do. It feels really good everywhere!

[ta man]

Thanks Rocky.

[Steve C.]

Thanks Rocky.

X2

(I presumed a 3.55 rear gear in my comments )

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[Cliff R]

Good info Rocky x 3.

I'd be interested in knowing how much timing the engine will tolerate at WOT and for "normal" driving. The combinations I've been involved with that were big CID, high compression, and relatively "small" cams didn't need much timing anyplace to be happy........Cliff

[Steve C.]

I'd like to see the dyno sheet.


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[72LuxuryLeMansLa.]

Originally Posted by Steve C.

I'd like to see the dyno sheet.


.

+1

[71 T/A]

Rockey, when is your 1970-81 Firebird/Trans Am Guide coming out?

[Rocky Rotella]

Cliff, peak power was made with 32 degrees of timing. I curved the HEI with the previous combo and it advances nice and smooth. I also limited vacuum advance down to 10-12 degrees. So far the engine doesn't have a hint a trouble starting hot or getting too warm. But the compression ratio is only 10.5:1 with aluminum heads and fast-burn chamber, so hopefully it won't be too sensitive.

71 T/A, it will be available in January 2018. All 224 pages!

[Rocky Rotella]

Dyno sheets are attached.

[andy kelleman]

Originally Posted by Steve C.

Of interest, another 4.500 stroke low rpm street build. Not to detract from Rocky's 495 CID build but to aid as a comparison for conversation.

Note it used a rated "850 cfm" carburetor, however at peak power the SCFM was a lower 622. And a larger 236 degree hydraulic roller cam in use. Also note the power band of Rocky's 495 CID engine is wider in the range of operating speeds under which the engine is able to operate efficiently. A 1400 rpm spread between peak torque RPM and peak power RPM. Whereas the 501 CID engine as presented here has a narrow 800 RPM spread. However it was reported they didn’t have the luxury of spending additional dyno time for fine tuning or experimentation.

Max power was recorded at 525.4 HP at 4900 rpm, and max torque was 604.8 lb-ft at 4100 rpm. SCFM at max HP was 622.

In short:

455 block

4.210 bore

4.500 stroke

6.7 rods

Ported KRE d-port heads

Comp XR288HR 236/242-110

Hurricane single-plane intake

Holley 850 cfm Ultra XP carburetor

Hooker Super Comp headers, 1.750” primary tubes and 3” collectors.

https://theshopmag.com/features/pontiac-501-dyno-run



.

i saw you where talking about this motor i purchased it after it was dynoed
from mike the engine builder and my son and i installed it in a 1973 ventura bracket car

[Steve C.]

" saw you were talking about this motor i purchased ..."

Andy,
Can you furnish additional information regarding the cylinder heads in use for your 501 engine. I read the 5 part article and it was a bit elusive regarding the amount of port work done to them, no flow numbers presented. Do you have any numbers to share ? Also noted the port volume was listed as 310 cc's. That seems a bit on the high side based on my records for ported KRE d-ports. That said, I have no personal experience working them. Also I know the Hurricane/Tomahawk single-plane intake 'as cast' has small port exit dimensions and takes quite a bit of work to match them to tall ports, not much info provided there as well.. what gasket was used ? From my experience they will go about 2.300" tall and leave about 0.125" above for gasket seal.

Last... any race weight and track numbers to report


.

[ponjohn]

Originally Posted by andy kelleman

i saw you where talking about this motor i purchased it after it was dynoed
from mike the engine builder and my son and i installed it in a 1973 ventura bracket car

Have you run the car? What rear gear?

[hurryinhoosier62]

Rocky, too bad Pontiac never built a truck. This would make a great engine to tow with!