1967 Chevrolet Chevelle SS - AMD Baseline Test

Cracked Up - With plans to see what our ’67 could do with a fresh big-block, we strapped it to our chassis dyno and got a nasty surprise.

Patrick Hill Feb 5, 2014 0 Comment(s)
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After getting our 413 big-block dyno tested, we rushed it back to the shop for installation in our '67 Chevelle SS396 project car so we could establish all our baselines before we start modifying it.

After dropping in the Rat and hooking everything back up, we made the usual post installation adjustments, then strapped the car down on the dyno to see what we had after all those ponies went through our factory torque converter and equally stock but-not-original-to-the-car Powerglide transmission. After two runs we had to shut down because of a puddle of ATF spreading under the A-body, but managed a full pull that showed 282 hp and 304 lb-ft of torque. Here's how the chassis dyno numbers compared to our engine dyno numbers:

Engine Dyno
Chassis Dyno
RPM HP Torque HP Torque
3400 292.4 451.7 195.59 302.13
3500 297.5 446.4 201.30 302.08
3600 300.5 438.5 208.32 303.93
3700 308.5 437.9 212.14 301.13
3800 314.8 435.1 219.87 303.89
3900 323.0 435.0 225.56 303.76
4000 332.5 436.6 230.55 302.73
4100 338.5 433.6 236.88 303.45
4200 343.7 429.8 241.85 302.44
4300 353.5 431.8 247.13 301.85
4400 354.6 423.3 251.24 299.90
4500 360.0 420.1 256.01 298.80
4600 367.3 419.4 261.08 298.09
4700 374.7 418.7 266.34 297.62
4800 372.4 407.5 268.70 294.01
4900 375.4 402.4 271.60 291.12
5000 382.7 402.0 272.79 286.55
5100 388.4 400.0 273.10 281.25
5200 391.8 395.8 278.35 281.14
5300 397.6 394.0 280.15 277.62
5400 407.9 396.7 280.89 273.20
5500 408.0 389.6 281.96 269.25
5600 411.1 385.5 278.75 261.44
5700 411.5 379.2 275.56 253.91
5800 411.8 372.9 274.06 248.18
5900 409.2 364.3 N/A N/A
6000 411.0 359.7 N/A N/A
AVG 364.45 411.38 251.59 289.58

We were down about 130 horsepower, and about 150 lb-ft of torque. This fell in line with similar drivetrain losses we'd seen in previous dyno testing using vintage cars and old-school transmissions (see our February '10 issue, where we tested an LS6 Chevelle, a COPO Camaro, and a '57 Bel Air with a 283). Because the engine was only spinning an alternator and non-clutch fan on the front end, most of the parasitic loss was coming from the Powerglide and torque converter. The next question was, what would this translate to at the track?

First we had to fix our transmission leak. Looking underneath the car, it seemed our trans pan had lost interest in doing a good job of sealing things. A quick call to National Parts Depot got us a brand new, stock sump pan, and a quick trip to Napa got us a fresh pan gasket. Drain fluid, change pan, dump fluid back in, good to go. Or so we thought. A quick test drive and we still had a puddle underneath the car. ARGH!

Back on the four-post lift, one of us sat in the car with the engine running while another was underneath with a flashlight looking for the source of our ATF loss. Whenever someone yells "Shut it off! You gotta come down and see this!" the sight you'll soon behold won't be pleasant. And it wasn't.

As you'll see, our Powerglide case had split from the passenger side all the way to the driver's side in the area of the reverse piston. As our friend Scott Miller at TCI responded when we sent him a picture, "Ouch!  And it can't really be welded in that area. That's where the reverse piston is and it would melt the lip seals unless it was disassembled. We usually scrap cases that are busted there."

We were just thankful this all happened on the chassis dyno and didn't turn disastrous. If the case had fully split while on the track, ATF would've sprayed onto the hot exhaust pipes and burn the car to the ground—if fluid hitting the rear tires first didn't send us careening into a retaining wall.

So, no drag testing with the Powerglide, unfortunately. The next step? While we were on the phone with Scott, we got everything ordered up to replace our broken Powerglide with the brand new TCI 4L80E transmission we built for the AMD Chevelle in the August 2013 issue. Look for that install next month. Then we're off to the strip!

Amd 1967 Chevelle Bbc 413 2/10

1. On the engine dyno, our 413 big-block cranked out 411.8 horsepower at 5,800 rpm, and 452 pound-feet of torque at 3,400 rpm, with a broad, flat torque curve above 400 lb-ft—definitely no slouch.

Amd Bbc 3/10

2. Back in the AMD Chevelle, we bolted everything together. For the nitpickers, yes, we had a little Permatex blue silicon run over, but we wiped it away afterwards.

Amd Bbc Exhaust 4/10

3. While on the engine dyno we ran the 413 through headers, but back in the car we hooked the big-block to factory cast iron manifolds. Later on we’ll do a header swap, and see how much of a restriction the factory manifolds were for our engine.

Amd Bbc 5/10

4. The only accessory our big-block has to spin (for now) is an alternator, so there’s not much parasitic loss on the front of the motor.

Amd Bbc Cooling 6/10

5. Likewise with our fixed cooling fan, not much parasitic loss here.

Amd Bbc Coil 7/10

6. Just like on the dyno, we’re using a stock ignition coil and single points distributor. Later we’ll do a high-energy ignition upgrade and see what the results are.

Amd Bbc Dyno 8/10

7. Here’s the dyno graph from our run. You can see the strong, flat torque curve on the motor, along with where our horsepower starts to fall off on the top end. We’re curious to see what going to the 4L80E does to these results. We’re also looking forward to not puking ATF all over our chassis dyno and shop floor.

Amd Bbc Oil 9/10

8. After two passes this was under the Chevelle (the oil puddle was from the car on the dyno before).

Amd Bbc Tranny 10/10

9. After swapping on a new transmission pan from National Parts Depot and still having trouble with fluid leaking out, we started looking elsewhere and discovered this fissure going from the left side of the transmission case to the right. The source of our fluid leak was found! This also meant no track testing for us with the Powerglide, as it was now officially toast. So, on to our 4L80E swap in the next issue!


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APE Racing
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