Packard Forum Index » V-8 (1955-56)

So as not to be derelect of my infamous modu operandi to beat a dead horse i found the following AL plug info:

Autolite plug info:
Consider the AL # of the general form WXYZ.

Z = heat range of 4 thru 6. 4 = cold.

Y = an odd or even number to indicate NONresistor or resistor respectively.

W and X are somewhat ambiguous in that the book only indicated "plug family" such as thread, reach, hex, tip etc but with NO specifics as to which codes mean what.

I wanted the BP4ES because Randy had mentioned in another thread that he'd be using them for some time. I got the R because that what was in the warehouse...I may switch to the colder BP5ES however. I won't get optimal performance right now from any plugs as a valve job may be in order soon

Because of discussion includes talk about heat range and because I'm no expert on the science of ignition, I decided to do some more research with a view to sorting out the best NGK plug for my '56 Pat - BPR5ES or BPR4ES. The Champion website cross references the original N18 to RN14YC (resistor) and the NGK US website cross references this to either the BPR4ES or BPR5ES. The NGK AUS website only cross references the RN14YC to the BPR5ES. I also cross referenced the AC R45XLS on both NGK websites and came up with BPR4ES (US) and BPR5ES (AUS), so I'm left in a quandary about which way to jump. Randy B likes the hotter 4 but Jack V suggests the 5. I am due for a new set of plugs so advice to help ease the pontification would be greatly appreciated. The motor in the Pat is in good condition and I'm also running Pertronix electronic ignition. Cheers John

If u plan to drive the car at high continuous speed under high heat conditions then use the cooler plug. If the car is used as a lot of stop and go and very lite duty use run the hotter plug.

When I bought my 56 Caribbean it had Champ RN14YC plugs and they appeared to be the correct heat range and were performing well - probably 75% of my driving is local or short-trips at Interstate speeds. Perhaps 25% is touring at prolonged Interstate speeds.

When plug replacement time came along I changed to AutoLite 65 plugs which have performed equally well.

Thanks Owen. I cross referenced AL65 on the NGK AUS website and came up with BPR5ES, exactly the same as the Champion RN14YC. BPR5ES's are what are in the car and I haven't had any problems with them so I'm now thinking I'm probably better off sticking with them. I don't do any power driving, maybe 25% local driving and 75% highway cruising, although rarely exceeding 60 mph, usually 55 mph. I guess I just needed some reassurance about what's best for the car. Cheers, John

JP, I don't know how much you're into authenticity or top-end judging, but if so one advantage of the AutoLites, depending on vehicle year, is that they still have a black oxide finished metal shell and I believe cadmium-plated shells are incorrect up thru 1955. I recall at a Packard National some years back seeing a very lovely 55 drive onto the judging field and watched the owner burn the hell out of his hands changing his plugs to black-oxide plugs, looking to avoid that last tiny points of authenticity deductions (1956 was the first year for Cadmium plated plug shells, according to PAC judging advice.) Though I strongly value authenticity, things like that make me glad I'm not into the judging scene.

Quote:

JP, I'm probably chiming in too late, but here is a bit of info on the Champion N-18 and RN-18YC. The RN-18YC differs from the N-18 in that the "R" indicates a resistor plug; the "Y" indicates a projected center electrode; and the "C" indicates a copper core.

(o{I}o)

G'day Owen, No I'm not into that scene - I'm all for driving and enjoying our Packards, warts and all. I'm a director of our State's region of the AUS Packard Club and many moons ago we decided that we wouldn't continue running an annual concours, essentially because some were taking it all too seriously. Instead each Christmas meet we hold a "Peoples' Choice" award where those in attendance can vote for the car they like best (as long as it's a Packard). Seems to work pretty well and my Patrician has come in third a couple of times, which was nice.

I was talking to a mate the other day and telling him about the discussion on spark plugs and he asked two interesting questions - 1, if the plugs are in good condition now and working well, why do I want to replace them? and 2, if I am going to replace them with NGK BPR5ES, why don't I use BPR5EY instead, which he said is the same plug but with an inverted "V" cut into the tip of the centre electrode?

As far as "1" is concerned, I just thought it was time. They have been in for two years and the car has done 9,000 miles in that time, but I'm not really sure when plugs should be replaced. With "2", he said the "V" tip is a patented NGK idea and designed to divide and force the spark to the outsides of the electrodes which improves combustion, efficiency, power, mileage, etc etc. I'll have to research this a bit more but if correct and all positives, and the plugs are available at the same price, why not use them instead. I do have this nagging suspicion though, if they're so good, why do NGK still make the BPR5ES (???). I keep everyone posted on how it turns out. Cheers, John

I look forward to your observations with the various plugs. Back in the days of heavily leaded gasoline, about 10,000 miles was a reasonable time to replace plugs, but today with no-lead they seem to last for many times that, 30,40, even 50 thousand miles or more.