Packard Forum Index » V-8 (1955-56)

Thanks for the response to my query Jack. I just look at a Stude 289 and it is so much smaller I assumed it couldn't be as heavy. I have a forged crankshaft in my Caribbean so it had to be a replacement. I never drove a Stude-powered Hawk but if they handled as poorly thru a turn as the 56J, there had to be a lot of stained seats in those cars. I enjoy this discussion and the info you bring to the forum.

Hi, Randy,

The Packard V8 uses the same basic v1.0 Kettering architecture (Cadillac, Oldsmobile and the v1.5 Pontiac)as the Studebaker V8. It is just longer and slightly taller. Holes don't weigh anything, so the larger bore diameter, 4" versus 3.5625" is part of the reason for parity. The Packard crankshaft has hollow throws versus the Studes solid forging.

By the time Packard got their v1.0 V8 into production, GM had moved on to v2.0 OHV with the Chevrolet (ball-stud rockers, separate center exhaust ports, intake covering the lifter valley). Ford used v2.5 with their thin-wall block in 1962. Put one of those beside a Studebaker. The Ford small-block was produced in essentially the same displacements as the Studebaker (221", 260", 289" and 302") but weighs 230# less and is only 2/3 the physical size, other than length. Put a SBF in a Stude engine compartment and it looks little and lost. Compare the engine compartment of Stude V8 hardtop with a '56J and it is obvious how the Packard engine is about 2" longer, depending on where one measures, and slightly taller. However, since the Stude V8 carb hits the hood anyway, the extra height is in the front. Both completely fill the engine compartment. The Stude V8 is ungodly big and heavy for its displacement. The Packard 374" V8 is only at the high end of average weight-to-displacement. If either Studebaker or Packard had gone to the design displacement limit, a 390" Studebaker or a 500" Packard would have faired much better in comparison.

As previously mentioned, high-RPM racing OHV8s have all gone back to v1.0 shaft-mounted rocker arms and a separate intake manifold and valley cover (Air Gap), but most have gone to v3.0, with alternating intake and exhaust valves.

thnx, jack vines

Couple of thoughts here...

I just finished reading an interview with Duncan McKellar who was chief engineer at Pontiac when they brought out their V8 in 1955. They asked about the rumors that Packard copied the Pontiac V8 or somehow an ex Pontiac man was involved in the Packard design.

He said at the time, Pontiac bought their machine tools from a Detroit company that sold to all the auto companies. They came out with a new way of making the cylinder heads which influenced the Pontiac design.

No doubt Packard bought from the same company and was similarly influenced.

To clinch the argument that any similarity was completely coincidental, he pointed out that Pontiac used 4 bolts around each cylinder while Packard used 5. Of course this meant they had a different design spec from the very beginning.

Now on the subject of engine weights. I have seen charts of engine weights and specs going back to the 50s, which claimed the Studebaker and Cadillac V8 weighed the same, 625 pounds. This always seemed suspect to me. The Stude was shall we say, influenced by the Cadillac and resembled a 3/4 scale model so how could it weigh the same? Also the Cad was one of the first OHV V8s out, and that first generation was heavy. All the others of that time period were 100 pounds heavier than the claimed Cadillac weight.

I suspect there was something wrong with the Cad weight, such as weighing the engine without accessories such as flywheel, air filter, generator, etc. while the others were fully equipped. This could easily happen if the info was compiled from manufacturer's published info that did not go into detail.

Quote:

Small tidbit of knowledge that a lot of people don't know: A Cadillac V8 intake manifold will fit a Studebaker V8 with minor modifications. The engines appear to be so close in size externally from what I've seen in person, and since the Studebaker is smaller displacement, it'll have more cast iron in it, make it plausible to me. Out of the two engines, however, I would prefer the Studebaker hands down. Gear drive timing and a strong bottom end make for a good engine. Packard should have joined with Studebaker right after WWII, and worked with Studebaker on developing the Packard V8. It probably would have had a positive impact.

Hello,
I am new here. Most of my previous experience with old iron has been Ford 1955-1964, and Buick 61-67 215's and 300's. I am considering buying a 1955 Nash, which has a 320 Packard motor.
What is the combustion chamber volume and CR of these motors originally, and how much can the heads be milled safely?
If you know of any sites with specs like valve size, bore, stroke, journal sizes and so on I would appreciate it.
Are rebuild parts available?
Lots of questions for a newbee.
Mike

Welcome!

I'm not totally sure on the combustion chamber size, I don't know of anyone who's cc'd them. As for the rest of the specs, download the V8 service manual from here, as it will have all the info you're looking for, except the cc's and the max milling.

If you're looking to make a performance engine out of it, I'd recommend '56 heads, as they have larger intake valves and a higher compression. There's probably several people on here who would have an extra set, myself included.

One other thing to look for, on the head, near the center exhaust port, is the part # of the head. Look and see if it has "CD"(Cast Dome) on the end of the #, if it does, it's the later '55 head. If it doesn't, it's the earlier machined combustion chamber head.

As for rebuild parts, there's TONS of stuff out there, if you know where to look. Most of the Packard parts places will have everything you're looking for, but if you're looking to make a performance engine, then I'd look at custom forged pistons. I don't really have much faith in the Egge cast pistons that everyone is selling.

Thanks for the response. I would not want to make a performance engine, but would like to have a compression ratio close to 9:1. Most of the early OHV engines came with pretty low CRs it seems. 9:1 would make for more efficient combustion and better mileage.

FWIW, the cost to rebuild any of the engines is about the same, so no one besides Eric would waste his time with a 320" ;>) Build a 374" and have bragging rights. The good news is most of the Studebaker-Packard (but not Hudson-Nash version) 352: and 374" engines came with a compression ratio in the 9:1 - 10:1 range.

On most of the heads I have measured, the combustion chambers are in the 78-83cc range. If you are not building a performance engine, either the '55 or '56 head will be fine.

I am in the process of rebuilding two 352" blocks and boring them to 4.125" so as to use Packard OEM 374" pistons. I completely agree with Eric, Egge Machine replacement pistons are OK for for show cars and casual street driving if clearance is at least .003"-.0035", but definitely not a performance application.

Also, I have two .030"-oversize 352" engines already rebuilt and on the shelf. If you are interested in any of these, let's discuss it off-forum.

thnx, jack vines

Everyone seems to have a problem "not trusting" Egge pistons. And later noted that they would have to be fit with .003 to .0035 clearance. Egge recommends a clearance of .0025 to .003 on their V8 pistons. Why would someone install pistons with a different clearance than what the manufacturer reccomends? I would like to here why Egge pistons can not be "trusted".

Stewart. I don't know about Egge pistons except what i have heard in various forums both Packard and NONPackard related.

However, The clearence issue might be determined by placeing an Egge piston on the oven at 200-250 degrees for a 1/2 hour and then remove it and measure it real fast with a mic to see how much it grows. Do the Egge V8 pistons have an offset gudgeon???