This photo shows the TA Performance SPX single-plane intake used during most of this month
Did you miss it last month? CC built a very basic Buick 455 and dyno-tested multiple combinations of two camshafts and four intake manifolds. It was entertaining, but the dead spot was in the stock cylinder heads. This month, the resolution: We're going to see how the stock, Stage 1-spec iron heads look when faced with Edelbrock and TA Performance heads in this big comparo of price, features, and power.
As a refresher, the 455 short-block we're beating on is a nearly bone-stock rebuild by JMS Racing Engines, with the only upgrade being Speed-Pro forged pistons (PN L2353F) in a 0.030-inch overbore that are custom-notched for valve clearance by TA Performance. With the 70cc chambers in the baseline iron heads, which TA upgraded to Stage 1 valve sizes, the compression ratio is a measly 8.77:1. All our testing was done with a Holley 750-cfm Street HP carb, an MSD ignition, E3 spark plugs, and a Meziere electric water pump. Thanks to local Buick guy Bruce Kent for loaning us a flywheel.
The variables in last month's testing were the cams and intakes. We found the best horsepower combo to be with a TA Performance SPX single-plane intake and the company's TA-413 cam, a hydraulic flat-tappet grind with 234/244 degrees of duration at 0.050, a lobe separation of 113 degrees, and lift of 0.500/0.500 with the stock rockers. That's the cam and intake used for the first set of head testing, but stay tuned near the end for some info on a combo with a smaller cam and dual-plane intake.
Stock Vs. Edelbrock Heads
The Edelbrock aluminum cylinder heads for Buick V-8s are PN 60049, fully assembled. At press time, the heads sold for $947.95 each through Summit Racing. These heads feature 2.125/1.75-inch valves, the same size as the stock Stage 1 iron heads. The Edelbrock chamber size is 68 cc, so the compression ratio was bumped from 8.77:1 to 8.81:1, which is barely worthy of note.
This graph shows the power difference between the Stage 1 iron heads (blue lines) and the
The Edelbrock heads change the valvetrain arrangement away from the stock-style shaft-rocker setup and are instead designed to use stud-mounted small-block Chevy rocker arms for 3/8-inch studs. If you're doing a swap on an otherwise stock engine, you'll also need to order longer pushrods, though the specific length will depend on the aftermarket rockers you choose. We used Comp Cams PN 1301-16 Pro Magnums in a ratio of 1.52:1. The stock Buick ratio is 1.55:1, but though we did not check to be sure, we felt confident that the stock rockers don't quite add up to the full 1.55:1 ratio. Stockers usually don't. But even if they do, the difference in lift between the 1.55:1 Buick setup and the 1.52:1 Comp roller rockers would be 0.010 inch. If a little bit of lift is worth a horsepower or two, then it's made up for in the roller rockers versus bearingless shaft rockers. We ran the Edelbrock heads with the as-installed valvesprings.
There's a bit of apples and oranges going on with minor differences in compression and valvetrain, but we feel comfortable bench-racing it into irrelevance, especially when you see the huge power gain when going from the stockers to the Edelbrock heads. The Edelbrocks killed the stockers at every point in the rpm range; at the peaks, they were better by 24 lb-ft and 42 hp. Combined with the weight savings of the aluminum Edelbrocks, that's really significant. And if you like the bragging number, the swap took this mild Buick from 459 hp to 501 hp at 5,400 to 5,500 rpm. Peak torque was 519 lb-ft at 3,900 to 4,000.
Costwise, let's assume you're building an engine from scratch. The rebuilt iron heads from TA Performance are $1,395 a pair. Summit charges $1,895.90 for two Edelbrocks. The stock Buick replacement shaft-rocker sets are $155 from TA Performance; the Comp Cams Pro Magnum Chevy rockers required by the Edelbrock heads are $285.95 from Summit. Chances are good you'll need custom pushrods for either combo, so that price is a wash (though technically, the Edelbrocks require hardened pushrods for guideplates and the stockers do not). Therefore, you're into an extra $631.45 for the more powerful heads.
Here's what the power curves looked like when we compared the Edelbrock heads (blue lines)
Edelbrock Vs. TA Performance Heads
While TA offers a number of cylinder heads for serious Buicks, this test involves the company's most basic aluminum heads, the Stage 1 SE. The big claim to fame on these is that they look totally stock with all the factory contours, unlike the Edelbrocks with their flat-machined ends. Paint the TA heads and they could pass for OE equipment. They also use the factory-style shaft-rocker setup rather than the Chevy rockers. TA claims that no additional parts are required when swapping these heads onto a running engine, though we found that not to be entirely true: The rocker pedestals are 0.100 inch taller than the stock heads, requiring longer pushrods.
The TA heads also run a little harder than the Edelbrocks, delivering slight power gains above 3,600 rpm that grow to more significant improvement above 4,500 rpm. Peak to peak, the TA heads gain 7 lb-ft and 12 hp. The biggest separation is past the point of peak horsepower; at 6,000 rpm, the TA heads are better by 25 hp. This is an indicator that, given an even larger camshaft that would generate more rpm, the TA heads would be the better choice. Looking at the average from 2,200 to 6,000 rpm, the Edelbrocks make 482 lb-ft and 378 hp to the TA heads' 489 lb-ft and 385 hp.
With the TA heads, we had the best-yet peak numbers of 527 lb-ft at 4,500 rpm and 513 hp at 5,600. But what about money? The TA heads sell for $2,450 a pair, which is $555 more than Summit gets for the Edelbrocks. Both heads need custom pushrods, so there is no difference there. If you already have a stock shaft-rocker setup, then you can reuse it with your TA heads, whereas the Edelbrocks will require the purchase of a Chevy rocker set, which could quickly eat up more than half of the cost savings unless you go with stock Chevy stamped-steel rockers and jamb nuts. If you need new rockers, then the TA heads can use the far less expensive replacement stock parts, but if you opt for roller rockers, then the shaft-rocker setup is significantly more costly than the Chevy rockers used on the Edelbrock heads. So your decision needs to come down to your rocker needs, the rpm range of your camshaft, and your desire for stock appearance of the TA heads.
The results with the TA-413 cam and the dual-plane Edelbrock B4B intake also show the TA h
Next, we compared the Edelbrock and TA heads using the TA-413 cam and the B4B dual-plane intake. The results were similar to what we saw with the single-plane, with the TA heads outrunning the Edelbrocks at points above 4,500 rpm. The Edelbrock-headed test produced 532 lb-ft at 3,700 to 3,800 rpm and 473 hp at 5,400 to 5,500. The TA heads delivered 534 lb-ft at 3,700 and 487 hp at 5,600 rpm.
This was one of the most interesting comparisons in our two issues' worth of Buick testing
What About The Small Cam?
Looking at last month's story, we admit that we kind of dug the combination of TA Performance's little TA-212 cam and the Edelbrock B4B dual-plane intake. The cam specs are tame, with 218/230 degrees of duration at 0.050. The lobe-separation angle is 112 degrees, and valve lift is 0.459/0.470 inch. It made gobs of torque, but could it have been better with improved heads?
Yes. Way. We did an A/B com-parison of the stock heads versus the Edelbrock heads using the TA-212 cam and B4B intake. The Eddy heads made improvements worth talking about at every rpm point. The peaks improved by 22 lb-ft and 31 hp, giving us 535 lb-ft from 3,500 to 3,700 rpm and 457 hp at 5,300 rpm.
What's really interesting is that this combo destroyed every cam and intake setup we tested last month. With stock iron heads, the big TA-413 cam and large SPX single-plane lost 40 lb-ft and made just 2 more horsepower than the small cam and intake with the Edelbrock heads.
Next time you're sitting around wondering if you should go for the bigger cam or the better heads, we'd say nab the heads first. We'll always argue that the bigger cam should come next, but it was really hard not to like our supertame, stump-pulling 455.
Overall, we still think stock iron heads are decent with a small cam, and they can be money savers if you have good cores to work with. However, the Edelbrock and the TA Performance aluminum heads offer a significant performance improvement with any camshaft. Whether you choose the Edelbrock or the TA heads depends a lot on how much you care about stock appearance (which the TA heads offer) and what you intend to do with your cam and valvetrain. With a small cam and performance under 5,000 rpm, the heads are nearly equal. If you want more top-end performance, the TA heads are better, but at a higher price. The TA heads use stock-style rocker shafts that save money if you use stock parts but that cost more than the Edelbrocks if you want to step up to roller rockers.
Either way you go, there's nothing wrong with Buick power.
An advantage of the stock heads and the TA versions is they can be used with the stock sha
This photo shows how the TA Stage 1 SE aluminum head on the left is nearly identical in ap
From left to right are the stock iron heads...
...and the TA Performance versions (the last of which has slightly larger valves). The com
These photos compare the different shapes of the spark plug holes on the Edelbrock heads..
...and the TA units. With the Edelbrocks, a little grinding would have been needed to clea
We used E3 spark plugs throughout our test. The only thing notable about this is that the
|ARP||JMS Racing Engines|
|Ventura, CA||Monrovia, CA|
| ||Lucas Oil Products|
|Ponte Vedra, FL||800/342-2512|
|Torrance, CA||MSD Ignition|
|800/416-8628||El Paso, TX|
|Holley Performance Products|| |
|Bowling Green, KY||Percy's High Performance|
|270/781-9741||Linn Creek, MO|
|Hooker Headers (a Division|| |
|of Holley)||Rockett Brand Racing Fuel|
|Bowling Green, KY||Glenview, IL|
| ||TA Performance|