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I have a new set of AC 45R plugs to put in. They are supposed to be the closest thing to the Champion J8 that was specced for all '54 327 engines. I got resistor plugs because that's what was available and in the car before.

NOW I go to gap the plugs, specced at .023 to .028, and most of the plugs were .030 right out of the box. I hate messing with plug gaps that are close, so I gapped all at .030.

Any disadvantages that I'm going to find performance or mileage-wise?

Maybe some advantages?

The car has an aftermarket coil called a "Blue Streak" which I imagine is a bit "hotter" than stock.

I pulled the #1 plug that was in there, and it was gapped at .025. I'm the one that gapped it.

NOTE:

A bunch of used Champions J8s I found in the trunk were gapped at .030. (They were in a box that was for AC 46 plugs! That's not a typo. 46 non-resistor plugs could be had at one time, for 99? apiece! I couldn't find 46 plugs any more, but they are in the Shop Manual specs for pre-'54 288 and 327 engines (along with Champion J8-5 and Auto-Lite A5).

Interesting that the '54 specification was J8 rather than the previous years' J8-5. Perhaps the -5 designation is for resistor? Maybe the '54 cars went to "Resistor wiring" which has been mentioned elsewhere as providing radio noise suppression without the need for resistor plugs.

Having the gap a little wide probably won't make any difference. If the ignition is marginal it could make starting a little harder, and the spark could thin out at high speed (90 mph+).

As long as you check them the way you should. If you leave them too long they could wear to the point where the gap is too big to start the car. But that would be after many tens of thousands of miles of wear.

I have never been really clear on the whole resistor wire/ resistor plug/ resistor rotor thing but someone may enlighten us.Is all three togeather bad? Resistance is only to prevent radio interference.(as I understand it)
Opening your plug gap does put increased demand/stresses on your coil, cap, rotor & wires though.
The Blue Streak coil is a NAPA brand & if not made in Trashcanistan is a premium piece. Any coil will only produce the amount of Voltage needed to fire your plugs so save your money on the "Thermo-nuclear Holocaust" brand

For the future you might also consider AutoLite 308, an equivalent to the J-8 in a resistor plug. I use these in all Packards with 14mm plugs from 1932 thru 1954 with excellent results. For possibly faster starting in more stressful situations I would however gap to 0.025".

Quote:

HAH! (I did laugh out loud at that crack. Nice to know that the "Blue Streak" is a good coil. The car has always started like it has electronic ignition with atomic blasters in it. Except for the time I flooded it in cold weather. Whoops.

Thanks for the reassurances, Rusty.

Blue Streak was the premium line of ignition products from Standard Ignition. Standard products were sold by most auto supply stores and considered to be good quality products. I don't know if they are still around. NAPA sells products made by Echlin another long-time, old time manufacturer. They are probably produced off shore these days.

I would re-gap the spark plugs to .025" and check to make sure that there are no more resistors in the ignition system (wires, cap, rotor).

JW,

You're right on the gap. I test drove it. Doesn't start right off like it did, and less power and acceleration with the .030 gap. You learn something new every day. The previous plugs were identical, AC 45R, although I doubt if they were made in Mexico, as the current set was.

Compression (cylinder pressure) test: varied between 115 and 125. I have all the readings written on the head in pencil and the car is in the garage for now so can't give them cylinder by cylinder here right now.

The compression test done the day after an oil change with 6 1/2 quarts of Valvoline 30 wt Conventional and 1/2 qt of MM oil. The car was driven about 15 miles after the oil change. The compression test was done the following day when the engine was almost stone cold. I just started it, backed out of the garage, took the old plugs out, did the compression test, and put new plugs in.

I think those are OK compression (cylinder pressure) numbers, but don't know for sure. It doesn't ping, but then I've got 95 octane clear gas in it. I guess variation between high and low cylinder pressure of 10 lbs or less is OK. It comes out to less than 10% variance.

(Also, before doing any of this, I did a good ol' fashioned Marvel Mystery Oil "soak and smoke" to try to break up carbon and loosen up rings/valve stems. After that, I drove it about 15 miles and changed the oil.)

All the old plugs looked pretty good. Gray ash, no wetness or oil fouling.

Thoughts? especially on the cylinder pressure readings, will be appreciated very much.

Thanks!

Guy, your compression test numbers look good with less than 10% difference between the highest and lowest cylinders and all with good numbers around 120 lbs. Looks like you have a sound engine. Keep up the good work.

(o{}o)

Thanks for your kind words, JW. I re-gapped the plugs at .025, and found that 5 thousandths makes a remarkable difference in starting and "punch."