Spark Plug choices - cooler

[aribert]

I'm not having any luck with the search function so I'll ask a question that has probably been answered several times before. I am getting detonation on hard acceleration. Currently I have Autolite 46 plugs in the engine and I also have: Bosch DR8BC, Champion RF11YC & Autolite BFR82 plugs that "look" like new that I pulled out of engine cores over the past couple of years. They all appear to be the same generic heat range (when compared to NKG plug cross reference chart).

I believe that one heat range cooler plug would be in order. What brand plugs / plug numbers are you running (and what major mods, if any, to the engine. My engine is (internally) a stock smog motor.

This coming winter the head will be pulled & milled and a lifter / cam upgrade will take place (possibly my existing Clifford solid lifter cam)

 

[SoCar72]

I second the question as this has been a puzzle to me for years.

Does anyone know how to or where to look to decode or cross-reference plug temp ranges in relation to application? Seems to be that the auto parts desk guys can't find this info unless it is on their computer screens. I suspect my 351w Mustang needs a step warmer.

 

[jamyers]

Offhand, the stock Ford 6 plug is at the hottest end of the heat ranges of most manufacturers, apparently we're "blessed" with really 'cold' combustion chambers. Makes it a pain if you want a hotter plug.

Couple of links with heat range info:
http://www.sparkplugs.com/sparkplug411.asp
http://www.dragstuff.com/techarticles/s ... rence.html
http://www.hrpworld.com/client_images/e ... 1391_1.pdf (Champion Plug info)
http://www.acdelco.com/parts/sparkplugs ... cation.jsp
http://www.ngksparkplugs.com/tech_suppo ... p?mode=nml

 

[SoCar72]

Jamyers - Everything you ever wanted to know and then some about spark plugs...

Way awesome! Thanks!

 

[350kmileford]

Would running a smaller plug gap help cool things any? My engine revs very high on the freeway, thus getting very hot. And you guys are telling me that they won't be able to tell me which is the coldest plug available at autozone, Napa, etc?

 

[wsa111]

I have had great luck with NGK 7510 iridium plugs.

The pin center electrode fires great at .050" plug gap & the heat range is very forgiving.

The cost is about $7.00 a plug, but they well worth it. Bill

 

[Mustang_Geezer]

Heres a link I keep in my favorites,

http://www.autolite.com/carcare/techSpecs.php

All kinds of info for Autolite sparkplugs.

Later,

 

[Harte3]

I was converted to NGK's back in the late 60's. I had a Cortina 4-banger that would eat plugs until I switched to the NGK's with a greater selection of heat ranges. Ran them in my 170 Ranchero, 170 Etruck, 360 F100, 350 Buick, 225 /six Duster etc., and currently run the V-Groove in my 83 F150.

 

[rbohm]

Would running a smaller plug gap help cool things any? My engine revs very high on the freeway, thus getting very hot. And you guys are telling me that they won't be able to tell me which is the coldest plug available at autozone, Napa, etc?

8) plug gap means nothing in regards to heat range.

 

[Ricardo Velez]

I recall normally running Autolite/ Motorcraft , BF-42, ,don't recall anything colder commercially available, on my race-only 200 ci Maverick, and they would live thru some extended drive-around the block, to warmup/ break-in fresh engines, normally re-rings were less than 3 months apart( running every single weekend). Always did index them, pointing the opening on the ground / gap area downward, slanted to the intake side, so the fresh mixture would wash away the gap . That always gave me a more even coloring on all cylinders...
Of course, using a 5.43 rear with 28.5 tall tires, it replicates long winded highway drives...I suppose.
...my 2 cents.
Ricardo

 

[Ricardo Velez]

On a different line, detonation could be caused by a few other things, like too much vacuum advance too early, poor fuel quality or old fuel supplied to the normally used gas station; or too lean a mixture( if you are using 32/36, a plugged / dirty jet on the 36's side, fuel or air correction).
Excessive oil leakage into the chambers thru the rings should show up as as small oily line on the side of the insulator, long before it starts going low on the dipstick.
Trying a colder plug might reveal that oil trace, since a cold plug don't stay hot that long during the exhaust cycle, after ignition and combustion in the chamber... the spark gap and the insulator is closer to the outside core, therefore dissipating heat faster and taking chamber heat with it, leaving behind the oily traces...
and that would be a very good indicator on which direction to look, inside or outside of the engine.
....2 cents more.
Ricardo

 

[SoCar72]

So you index your plugs gap down and slight slant toward the intake? I've only heard of people indexing with the gap toward the intake so the plug "cups" the intake charge. What gains did you find with this technique? Interesting...

 

[Ricardo Velez]

Indexing was normally used on very high compression engines with a very big piston crown, specially small displacement V-8's on the Mod Prod drag classes, just because the ground had to clear the notch on the pistons.
On lower compression ratio engines, it's just a matter of allowing the intake fuel charge to wash off the spent gases from the spark plug (on the way out anyways due to overlap first, and later the exhaust cycle), making the mixture spread more evenly and giving the plug a fresh mix of clean/ emulsified gasoline shower. As a result, spark plug reading is a lot more even piston-to-piston. You can see it by pulling all plugs, numbering them, and putting them side by side on the sunlight ( natural light, you want to see the real color as to make the correct jetting / ign changes).
So , they would have a mark along the ground all the way up thru the thread and insulator, and a number somewhere else..
I consider spark plugs the first step on the diagnostics to the inside of the engine, something like smelling the exhaust fumes ( for a VERY brief moment !! ) or listening to the intake side over the carb for even vacuum ...
Ricardo

 

[Ricardo Velez]

I tend to be long winded sometimes but, looking at the car description something came up...
-'73 dizzy with points. Question:
do you have the vacuum line connected to the carb or manifold? if so, pls make sure the the vac diaphragm is not broken or the points plate lost the little clip on the link and it's floating loose. How about a stuck open PCV valve on the valve cover?

Also, how about mileage? (worn out timing chain; easy to check with timing light at idle, mark should not wooble or look like floating.
pls keep us posted.
Ricardo

 

[SoCar72]

Terminology question, as I'm only a few weeks old here :

Dizzy - is this just forum-slang for distributor, or does it refer to certain mods or a certain ignition system.

 

[ludwig]

Dizzy, diz, dist = distributor
DS II (aka: dee ess two, DuraSpark two) = later model electronic ignition with ignition module.

 

[xctasy]

Love this post, its really helpfull because I'm using ancient non cross flow parts and yet there is a huge technical back-up for these engines, probably better than the X-flow is down here.

Does10's and Doug (Mustang Geezer) have helped me a lot with this link http://autolite.com/sites/default/a/upl ... 0107_0.pdf

From the factory, my B-code 3.3 ride came with Motorcraft BSF 92. The gap specs are 0.48 to 0.52 for my recomended type, .The latest Autolite chart says 6-3.3L 1 bbl. (B-code) is APP46, AP46 , or *46, with .050" or 1.27 mm.

At short notice, my original plugs have been replaced with the NGK interchange. Its the same I've seen for F150 4.9's, some 5.2 and 5.9 Mopars, the NGK AP5FS



They sit right down at a paltry 0.035" or just 0.9 mm (0.89 on my Powerbuilt Spark Plug Gap gauge). I guess I for-go use of the stock emissions placard setting, seeing as the plug is quite different, and use the NGK recomendation. I've raised the compression half a point to 8.9:1 with a 1963 head casting, but used a poorer quench 41 thou Monotorque gasket.

Anyone find the NGK heat ranges for the AP5FS okay at 35 thou gap?