Packard Forum Index » V-8 (1955-56)

Quote:

Good question, but maybe it would only appeal to the engineers on the board.

One major problem with the 348/409 was the angled deck. Most machine shops could not bore it.

One major problem with the early BBC was weight. It weighed as much, if not more than the Packard. Later, with the aftermarket involved, the "Rat" motor became a killer with alum heads, blocks and all kinds of cool stuff. Maybe the Packard would have evolved the same way, but I doubt it.

i dono, i herd something about that, but i never beleaved it. yer car looks like mine.custon clipper. well since im here, maybe you can help.. do you know where the "VIN" number is im going to reg, at the dmv, and thay dont have the number in the dmv system.

Perhaps your car is missing the VN tag? I have no idea what year car you're talking about, but 51-56 it's on the front driver's door pillar. 1940 thru 1950 it's on the upper face of the cowl, under the hood, driver's side. Before that back to about 1931 or so it's on the engine side of the cowl, usually passenger side. Prior to that it's sometimes on the inside of the cowl, above the brake/clutch pedals. If the tag is missing, there is no way to recover the number except by prior owner's documentation if you're lucky. For some reason I'll never understand, some people love to remove the VN tags and then loose them or peddle them on eBay. If you can't recover the #, then you may have to title with the motor number.

If it's a V8 Look at the engine near the oil filler tube. There should be a number of the form 55MM-9999 or 56MM-9999.

Someone indicated several months ago that the 56's (and perhaps earlier 50's models) have somekind of number stamped on the FRAME RAIL in the area under the right door pillar. IIRC the VN at that point.



I've not yet looked for it on my car.

Craig,

Quote:

Just the Packard VE would be nice to have. I think we might have some Chevy folks here who would have some figures for the BB, or I wouldn't be surprised if I can find some on Carnut.

I think this cries out for a comparison look-see. With Packard being maligned for the '55 V8's relatively minor "teething" problems, I wonder how the truly catastrophic failures of some of the original Chevy BB "W" motors escaped the kind of scrutiny often leveled at the Packard. It's the magic Bow Tie effect at work, I think.

OK, so I'll try to get the ball rolling here with Packard data.

This data from original Packard engineering sources was printed in the Summer 1991 edition of "Packards International." The issue is entirely devoted to V8 Packards and is loaded with goodies. Sure hope to get that posted here some day if it isn't already. Any ideas how to go about that, Big Kev?

The specs are for the 352 ci engine only.

Bore 4"
Stroke 3.5"
Stroke-to-Bore Ratio .875
Displacement 352 ci
Compression ratio 8.5:1
Designation of Cylinders:
Left F-R 1-3-5-7
Right F-R 2-4-6-8
Firing Order 18436572
Maximum Gross Brake HP* 260 @4600 rpm
Maximum Gross Torque* 355 ft/lbs @2400-2800 rpm
Maximum B.M.P.E., lbs/sq in 152.1@ 2600 rpm
Piston Travel 1480 ft/mi
Engine weight 698 lbs

*corrected to SAE standard conditions of 29.92 in. Hg. atmospheric presure and 60? F dry air.

I believe the engineering information in that issue was reprinted, with permission, from a published SAE paper. PI's magazine is likely copyrighted and the club may still have back issues available for sale. Also, SAE offers reprints of original reports for a price, but - again - copyrighted.

Quoting those specs and giving proper credit to the source is fine, but posting a reproduction of pages from a copyrighted publication, without express written permission, could put PackardInfo at-risk.

<h2>Volumetric Efficiency, percentage</h2>
<p>
This is data from DynoSim 2000. I tried to make these engines are similar as possible to get a "fair comparison".
On all 3, compression ratio is 9.5:1, carb is 4bbl 600CFM,
intake is stock dual plane, exhaust system is stock, cams are
similar, but not exactly the same.
</p>
<table border=1>
<tr><td><b>RPM</b><td><b>Packard 374</b</td><td><b>Chevy Gen-1 348</b></td><td><b>Chevy Gen-2 396</b></td></tr>
<tr><td>2000</td><td>69.8</td><td>68.9</td><td>70.2</td></tr>
<tr><td>2500</td><td>71.5</td><td>70.7</td><td>72.3</td></tr>
<tr><td>3000</td><td>74.9</td><td>74.8</td><td>76.2</td></tr>
<tr><td>3500</td><td>76.8</td><td>78.0</td><td>78.5</td></tr>
<tr><td>4000</td><td>76.5</td><td>79.7</td><td>79.2</td></tr>
<tr><td>4500</td><td>73.8</td><td>80.0</td><td>78.4</td></tr>
<tr><td>5000</td><td>69.4</td><td>79.0</td><td>76.3</td></tr>
<tr><td>5500</td><td>64.3</td><td>76.2</td><td>72.3</td></tr>
</table>
<p>
I think the reason the Gen-1 348 has a better VE curve is that it has a relatively good flowing head (somewhat canted valves slightly bigger than Packard) on a somewhat smaller engine (348 vs 374). The reason the Gen-2 BBC is not better is because the cam is too mild for even better flowing heads (canted valves). The Packard head is an inline wedge, of course.

Craig

Hi, Craig,

Interesting stuff. As you know, the DynoSim program depends upon assumptions. Help me understand the underlying logic here:

1. Just wondering why the choice of making everything the same, but not OEM equipment? Once we depart from OEM, then we could "improve" the Packard with a more intense acceleration cam profile and so on.
2. Where did you find the head air flow data? I've never seen anything published for the Packard V8. Were you using 290 horsepower as the goal for the 374" and then letting the program reverse-engineer the flow? Without real head flow data, I've found everything else is a guess.
3. Why choose a 600 CFM carburetor, rather than the OEM?
4. Why choose 9.5 C.R.?
5. Why not compare the 352" @ 9.5 C.R. against the 348" and the 374" @ 10.0 C.R. against the 396". On the 352", the 2" valves become proportionately larger.

Again, interesting stuff.

thnx, jack vines

Jack,

Good questions all. Here is my rationale on the points you brought up.

0) My general assumption was that this comparison would be something that Chevrolet engineering might have done back in the day when they were asked to evaluate the Packard V-8 (bean counter favorite) to what their design (Gen-1 W 348) would do. Therefore the common values cited above for all 3 engines. Of course the Gen-2 BBC really was only a glimmer in the eye of the engineers at that point in time, but I included it for hindsight comparison.

1) All 3 engines are pretty much OEM. I wanted a passenger car comparision, which would probably be one of the studies done by the Engineers. I have cam profiles for the Packard, but not the Chevies. So I chose profiles that were close to the Packard, i.e. approximately same VE at lowest RPM (2000). Obviously, changing cams for any of them would make a big difference in VE, particularly the Gen-2 BBC.

2) Head airflow data for Packard V-8. When I replaced the heads on my 55 Pat because of exhaust valve recession, I bought a set of used 56 Sr heads. With my prior Pontiac high performance connections, one of my old buddies volunteered to test the Packard head on his flow bench. That's where I got the flow data. Not unsurprisingly, it was fairly close to 1964 GTO head. I then extrapolated the numbers for the 56 head without sunken exhaust seats.

3) 600 CFM carb. Even playing field assumption. Obviously Chevy could have put the same square bore carb on all 3 engines.

4) 9.5:1 CR. Even playing field assumption that was common to all 3 engines at one time or another.

5) Why not 352 vs 348 and 374 vs 396? Time available for this analysis. That would be something worth doing, if there's no big objection about the simulation and we think we could learn something.

Craig