Packard Forum Index » V-8 (1955-56)

Try this one:
sparkplug-crossreference.com/index.php

BUT there is problem! A COMMON problem with using conversion charts for plugs over the years. Use the 45XLS to convert to NGK or AL. THEn use the NGK or AL number to convert back to AC. They DON'T convert back and forth consistantly.

So the only option is to take the AL 56 or 66 number AND deciper it's meaning. OR use the AC number. THen use that criteria to build the new more secular number. Mite not work. I don't know.

It takes a lot of power to turn the oil pump judging by how my big electric drill strains and gets hot when I run a pump on my test stand. That constant load insures the distributor shaft is always pulled down onto its thrust bearing when the engine is running. Thus no timing variation. Or am I missing something?

Last year when in the US I went into a NAPA outlet and asked the guy for a set of plugs for my 55 400 he looked in a book and gave me Champion H10C's and assured me they were correct. I haven't fitted them yet are they OK...?
The plugs I am using now are Autolite 216 and seem OK.

G'day Jack, funny how topics come along just at the right time.

I've just put my distributor in for reconditioning and was asked about the advance curve. Of course I only knew what is in the Service Manual, so I am very interested in whatever info you have on this topic. I have a '56 Patrician with a 374 and it's distributor is a Delco #1110865 (my spare is a #1110873).

Some time ago I fitted a Pertronix kit (#1183) into it and it has been performing well, with no problems. That is, apart from the timing varying occasionally, which we think might be due to sticking centrifugal advance weights, hence the need for reconditioning. I have also fitted the Pertronix 40K volt coil.

I have also fitted NGK plugs (#BPR5ES) which seem to work fine (I always go for NGK in all cars in the family), although I have never been sure what gap I should use, opting for a "loose" 35 thou. Should it be bigger? The R in the number relates to a resistor which is good for minimising radio interference.

Any info I can get about the advance curve would be greatly appreciated as I want to avoid as much pinging as I can with today's modern unleaded fuel, whilst not sapping power or mileage if I can avoid it.

Cheers, John

Does anyone running the NGK, Champion or AL plugs have any documentation for deciphering the characteristics of the plugs from their number?????

I have an older AC book that deciphers the numbers and have looked at several AL books. The AL books seem to be rather ambiguous and lacking detail.

I've never been able to find ANY information on ANY plug that was reasonably complete EXCEPT the AC.

Again, if the OLD Champion,AL or AC numbers can be decipherd according to plug CHARACTERISTICS then the NEW books can be used to determine a modern number for a modern plug with the same or very close characteristics.

Quote: You might want to check out bulletin 56T-14packardinfo.com/xoops/html/downloads/STB/56T-14.pdf and compare those specs with the ones you gave the mechanic.

There was a mid year revision and slight changes to the curves from those in the original specs. Not sure right now where your spare distributor number fits, but the one on the car looks to be the original without the revision.

Decoding chart for NGK:
ngksparkplugs.com/tech_support/spark_plugs/faqs/faqcode.asp?mode=nml

My computer can't down load it so i don't know if the chart is any good or not.

It's a 176K pdf file. If your email can handle that as an attachment, PM me an address and I can send it.

Thanks HH56 but i will try to download it myself later on at another 'puter. My email address does not handle attachments at all.

Quote:

Tuning a distributor to maximize power/economy and minimize pinging is a very labor-intensive process. Studebaker-Packard used the four different distributors mentioned above, plus they released a field service kit with different centrifugal and vacuum springs and vacuum shims to change the curves in the Autolite.

The four options:

1. Buy yourself a Sun or Allen distributor machine and make it your hobby to road-test and fine-tune your distributor curves. It'll take all summer, but fun if you like that sort of thing.

2. Spend money on a chassis dyno session, find which advance the engine likes at which fuel, load, road speed and throttle opening, then have a custom curve built in.

3. Use the existing distributor and experiment with finding the best compromise initial advance between 5 and 12 degrees.

4. Buy an electronic spark management system, such as the J&S Safeguard. This senses ping and retards the spark as necessary. I've got one more new one I got from Ted Harbit, the Studebaker racer. (Don't call Ted. He doesn't sell parts any longer.) They're expensive, but so is the labor to try to prevent ping with custom distributor curves.jandssafeguard.com/

jack vines