Packard Forum Index » V-8 (1955-56)

Quote:
".... m for an engine
on a clunker that was prone to fouling."

Run a HOTTER heat range of plug!!!! That can even cure OIL fouling as long as it is not excessive to the extent of blue smoke from tail pipe.

On AC plugs the heat range is 42 thru 48. 48 an EXTREMEMLY hot plug, for something like an ice tractor used in Siberia). 42 extremely cold plug (for racing or extreme high temperature load operation 10 to 24 hours per day.

The 44 or 45 heat range is moderate and most suitable for usuuaalll, normal, customary passenger car or lite truck operation.

Other plug manufacturers, who knows. AL seems to be consistent.

Thanks for the plug advice. I hadn't even thought that the engine might have 1955 heads on it, so I will do a depth of thread measurement tomorrow. So far, this car has given me no clue of such swapping in its past. This may also explain some performance issues if the plugs in it did not reach where they needed to. It could account for all those new plugs being the longer thread variety. I will try to stick with the Autolite 66 type, per your multiple recommendations.

Look on the head for number directly on top of the MIDDLE exhaust port in PLAIN VIEW.

6480407 = ALL 56.
440690 = 5560-80
440690 or 440689 0r 440855 or 440854 = 5540.

Seems that i recall some sccuttle buttle about EARLY 56's useing 55 heads. I'm not sure.

Also check BOTH heads incase someone only replaced one head or used miscellaaneous heads.

Best to also measure the thread deepth in the heads. THAT will overrule anyother possibilities.

Champion Spark plug is apparently the victim of goodwill plundering. The no nothing MBA's take over, they fire the engineers, they cheapen the merchandise, and then milk the cash flow until the brand is discarded. It's not much different than the mafia bust outs where they used the credit ratings of a business to acquire loans they had no intention of repaying. Gee, and who else does the same thing?

AC Delco used to be a really good product and seems to be doing better than Champion.

The Executive hardtop, with a build date of March 22 shows a casting number of what I believe to be 6480408. That's close enough to your 6480407 for me to try the longer thread Autolite 66s. Just for grins I also checked the June 14th built Esquire and it also has the 6480408 heads on it. It's running fine but I may pull the easiest to get to plug to see if it has the longer thread in it. I'll do a depth measurement on the Executive before committing to change anything more, unless I am certain.

On a related note, should we give consideration to amending the forum's Parts X-Ref to showing specific 1955 and 1956 differences in applications? All V8s might not be accurate. I'll leave that up to the experts on these engines.

Sure enough, pulling number three plug on the Esquire resulted in a long thread variety with a proper gap and a light chocolate insulator color. Pulling regularly changed plugs is certainly easier than the wrong ones that might date back to the late 1970s.

It's going to be our 55th consecutive day with Atlanta temps above ninety. With mosquitoes buzzing around in that heat, I know the difference between a must Packard chore and an ought one. Thanks to all who helped me in this incomplete endeavor.

Oh, on the off topic of the Moon car, a beautifully restored 1922 Moon touring car was parked a few cars down from my Packard at last night's Tucker Cruise In. From the crowds it gathered it probably won Best of Show with its Rolls Roycesque radiator. I don't want to highjack this forum, but many of us Packard people first noticed our cars because they looked so good from the front.

Just for S&G I checked Best Other.
Head is 6480406 C
I am using NGKBP4ES (NGK - no good kind) spark plugs.
Gave up on Champion years ago.

Casting number on both my 56 Caribbean heads (Utica engine #C1137) and my spare 56 400 engine (D2837) is 6480406CD. Anyone know the significance of the alpha suffixes?

"CD" = Cast Dome. Verses machined dome (machine dome early 55 IIRC OR maybe all 55 and early 56).

Then what does Randy's "C" suffix mean?

My thought was the suffix might identify the casting box or core set.