Stock Pontiac heads have tall,...
Stock Pontiac heads have tall, narrow runners, as dictated by the pushrod locations. The pushrod pinch in the intake port is the biggest bottleneck for making big horsepower with a Pontiac.
With the heads and intake taken car of, Andy set the valve lash at 0.016 inch, poured in an ample supply of Quaker State Q Racing synthetic oil, and it was ready to fire up. Adjusting ignition timing was a snap with the MSD crank trigger. Andy was surprised at the efficiency of the combustion chambers. "They only wanted 30 degrees of timing, and I was expecting maybe 34 or 36. With that compression, we've even gone up to 40 degrees sometimes." Jim insists that it is not only the combustion chamber's design that resulted in good low ignition timing, but the cooling passages in the heads. As water enters the block through the Mezeire water pump, it passes along all of the cylinders and then rises up through the heads. The cooling passages in the head are set up so that half of the coolant goes to the front of the head, and half to the rear. This necessitates four-corner watering, but customers have reported as much as a 10- or 20-degree drop in operating temps from running the heads. The dyno engine used individual water outlets for ease of installation on the dyno. Jim states: "The water crossover is a piece that you can use off of about any other Pontiac aluminum or iron intake. I didn't cast one into it because it seems like the first thing Pontiac performance guys do when they put on an intake manifold is they cut off the water passage so they can pull the intake manifold without draining the water." He also says that there are aftermarket manufacturers of the crossovers by themselves.
After a lengthy session on the pump at Westech's dyno facility, the 496-inch Poncho turned in an amazing 755 hp and 636 lb-ft of torque. What is even more astounding is how flat the torque curve was, making over 600 pound-feet from the hit at 4,900, all the way until 6,600 rpm. With that kind of torque, the Bandit's old Trans Am could probably pull a trailer load of beer all the way to Atlanta without the big rig! Poor old Sheriff Buford T. Justice would never rest again.
CV-1 Heads And Intake
When Jim Sammons of Roland Racing decided to up the stakes in the game of Pontiac go-fast goodies, he knew that in order for his new cylinder head venture to be successful, it would have to appeal to more than just a few souls. He would need to make his heads affordable and usable by the average racer and hot-rodder.
On the first count, with a retail price or $2,995, the heads are not necessarily giveaways, but they are definitely reasonable for someone looking to bolt on over a hundred horsepower. For that price, the heads come assembled with quality stainless steel 2.25-/1.73-inch valves, titanium retainers, and springs adequate for a solid-roller cam up to 0.800 lift. As an option, they have what they refer to as a convertible exhaust port. They will actually mill off the typical Pontiac-style downswept exhaust ports all the way back to the main body of the head, and the customer is left with an exhaust port design and bolt pattern similar to that of a small-block Chevy. Totally new and different, the convertible exhaust option has gained instant fans in the turbo world as it makes building a turbo header much easier.
As for the usability of the head, Jim claims: "The front and back of the heads do retain the full complement of bolt holes for alternator, power steering, and even air conditioning brackets will work too." Additionally, they use stock head gaskets with just minor trimming required in non-critical areas that would give clearance for the relocated pushrods. Every set of heads comes with clear instructions for the trim job. As mentioned in the article, the heads were designed for use with normal big-block Chevy rocker arms, and come with correct guideplates to locate 3/8-inch pushrods.
SD Performance Lifter Bore Girdle
There are several specialty manufacturers and suppliers to the Pontiac fold, but SD Performance has risen to the top for several of its components, most famously though for is its patented SD Performance Mega Brace. The brace consists of a set of contoured metal pieces that sandwich the lifter bores into a fixed position so that under the stress of an aggressive cam, the chances of breaking off one of the lifters bores is reduced to almost nil. Andy Mitchell of Outlaw Racing Engines says: "They'll break lifter bores on the passenger side because there is no support. They break the number 1, 2, and 5 lifter bore on the passenger side. When I get to the [Comp Cams] High Torque 440 lobe, then that's when it needs to happen. It has to do with the aggressiveness of the cam from seat to seat." A small application of epoxy helps bond the brace to the block, and seals the oil from pouring down the middle of the cam and crank.
The canted valves in the Roland...
The canted valves in the Roland Racing CV-1 head allow the relocation of the rocker arms, and in turn, the pushrods. The shift in pushrod location really opens up the design possibilities for a wider port without the pushrod pinch problems.
A big bumpstick requires a...
A big bumpstick requires a lot of stability up top. Running 7/16-inch diameter, 0.125-inch wall dual-taper pushrods is a smart move when the lift is near the 0.800-inch zone. Weight on the cam side of the rocker arm doesn't come with any appreciable penalty, but the benefits include reduced harmonics, more rpm, and more horsepower. Comp Cams had all the bases covered with the necessary hardware.
Laying the crank is that part...
Laying the crank is that part of engine building when you know things are coming together. By this point, Andy had double-checked all the clearances, put the rods on the pistons, and is ready to place the shaft in the Calico-coated main bearings.
Valves and springs all akimbo,...
Valves and springs all akimbo, the CV-1 heads demonstrate what canted valves are all about. As they open up, the valves move toward the center of the bores, unshrouding them, and allowing air and fuel to pass more freely.
Outlaw Racing uses every trick...
Outlaw Racing uses every trick in the book to make the stock Ponitac block live at its targeted 750 hp. Andy Mitchell was successful by using the lifter girdles, hard blocking the water passages, and installing Milodon steel main caps.
In their quest for power,...
In their quest for power, the Outlaw Racing Engines crew installed a Stef's crank scraper and trimmed it to fit tight, reducing windage. This might be a street motor, but it will see plenty of high-winding action at the dragstrip!
Though variances are rare,...
Though variances are rare, thanks to modern machining techniques, it is the engine builder's job to verify the cam specs. It also offers an opportunity to make sure the cam is installed with the desired amount of advance or retard. Many a timing chain has been caught installed a tooth off by simply degreeing the cam.
Comparing the Roland Racing...
Comparing the Roland Racing intake (left) to a common dual-plane, it is easy to see the difference in runner size in the NASCAR-inspired intake. The front water passage of the dual plane is commonly cut off to allow easy removal or replacement of the main intake spider.
Some minor trimming of the...
Some minor trimming of the head gaskets will allow the pushrods to sit in their new habitat. Clear instructions for the procedure are included with the CV-1 heads.
The Yella Terra rocker arms...
The Yella Terra rocker arms actually torque down directly to the head with lash adjustments to be made via the pushrod cup adjusters. The trunions on these rockers were stout enough that they actually touched just a little, and Andy had to trim a tiny bit to keep them separated.
After pouring in the Q Power...
After pouring in the Q Power 10W-30 synthetic oil, the engine was ready to get down and dirty. We like synthetics like Quaker State for a job like this; its shear strength affords the extra insurance we like with an expensive, solid-roller street motor like this. With the Peterson External pump providing an accurately metered amount, the pressure only varied from 57 to 62 psi during the whole dyno pull.
On the dyno at Westech, Dr....
On the dyno at Westech, Dr. Steve Brule checks on the health of the engine with a stethoscope. At least he's not reaching up the tailpipe with rubber gloves....
The '69 bird looks ready to...
The '69 bird looks ready to devour the completed 496. Andy Mitchell plans to install this bullet under the hood a few months down the line, and run it in some local races. If you're interested in one like it, Andy can build one for you.