Packard Forum Index » V-8 (1955-56)

G'day Mates,

Time for another update and I'll preface it by saying we've gone back to the drawing board for some more mod's.

Briefly, after doing a couple of mileage checks, while the old girl pulled smoothly and strongly, she's also using too much juice. First test showed AUS 14.2mpg (US 11.8mpg). After talking to my expert, he suggested testing the vac advance - the reco'd one fitted to the distributor with the Pertronix kit tested out at the factory spec of 16 degrees. The one fitted to the spare distributor tested out at 20 degrees even though both are numbered 1019111 (old age?). Anyway, he suggested swapping them and rechecking mileage, and this improved to AUS 15.5mpg (US 12.9mpg) - still not good enough given that I regularly achieved AUS 19 - 20mpg (US 16 - 17mpg) in the past before the distributor weights started sticking. My driving style is pretty relaxed, with a light right foot and she seems to do best on the highway around 55 - 60mph.

I'd be interested in finding out how this compares with other peoples experiences.

Given these results it was back to the shop with the distributor. I was informed that it had been calibrated somewhere between the factory specs and those detailed in Service Bulletin 56T-14. We are now going to completely ignore that Bulletin and structure a calibration more suited to the car, modern fuel and my preferred driving style. Part of this will be increasing the vac advance closer to 20 degrees as the car was coping fine with that amount with no pinging during the last test. The plan is to get economy at least back to where it was, without any loss of drivability. I'll keep y'all posted on how it works out. Cheers, John

Quote:


Kev,

No worries, I'm not suggesting more work for you, just an idea for a dedicated thread for posting modification tips like custom distributor curves, PCV systems, and other tips and techniques for improved performance, economy, reliability, emissions, appearance etc. Not radical mods but driveability, comfort and appearance things that enhance motoring pleasure. The "REQUEST" thread on the Modified board would be a possible venue, but, being a V8 head, I'd of course like one just for the V8's if possible.

Lots of people have great ideas and other people have practical ways to make them work.

I don't know how to (or even if I could) move a thread wholesale, but I've done a cut 'n' paste on my PCV thread, to put it on the "Modified' board in the "Request" thread.

If you can move that over "officially," and maybe somer other "transplants," I think it would be a promising start on this resource.

Thanks for all your good work, Kev.

Long live V8 PACKARDS! (and their predecessors too, of course).

Quote:


JP

Thanks for the continued updates on this thread. A very good learning tool. Your mileage of around 13 MPG US is very close to the long-term experience we had with three differnt '55 Packards, two Clippers with 352 ci, and one 400 with 352 ci. The things was, they all did about the same, whether you drove them 55 or 85 they came in with about 13 mpg. These engines were apparently engineered to increase greatly in efficiency with RPM increase, offsetting the normal wind and rolling resistances of higher speed driving. 13 was pretty good mileage if you wanted to drive 80 or 90 mph, not so great if you wanted to drive for "economy." They were supposed to be high-speed cruisers, I suspect.

The 400 had the heads shaved a full 1/8"-- that's right, .125. A radical experiement, but it improved performance greatly... although it made little difference in mileage. Higher compression apparently is not the key with these beasts, when it comes to mileage, but it sure seems to boost hp and torque (never had any dino tests, but you could sure notice it on the road--even with the twin ultra, it'd snap your head back when it dropped into passing gear).

I would guess that your 20 MPG figures are due in great part to the Pertronix system. Curious if you have mileage figures prior to that modification.

The fact that there is an electronic ignition system on this car means that it's likely that those with standard ignition systems will experience different results with the same distributor curves you are experimenting with.

Thanks again, Mate.

For whatever the information is worth, I had driven my 56 Caribbean about 6000 miles with conventional stock ignition and about the same # of miles after putting in Pertronix. Gas mileage did not change as a result, about 14.4 or so at Interstate speeds. This probably relates to about 16 mpg or close to it on pre-ethanol gasoline.