theformula

I was looking at acdelco.com and noticed that stock plugs, R45TS, have an extended tip.

The ones I bought ,R44T, are one level colder and are shorter, WITHOUT an extended tip.
Will this hurt performance?

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'92 Formula
305 TPI 5speed
1LE package
Mods: SLP headers,SLP catback,SLP air foil,ported plenum,Crane AFPR (42psi),MSD6AL,AC delco cold plugs, Bosch O2sensor, homemade cold air,K&Ns,3:73s,JET fan switch, Macewen white face gauges...Comp cam (i still have to install it )

JakeJr

Like most things, it depends.

If you're running slightly on the rich side, then the one heat range colder plug coupled with not having an extended tip will cause them to foul quicker.

The extended tip plug generally runs cleaner since it's pushed farther up into the combustion process and also exposes the spark to more of the mixture.

Usually a colder range plug is used when sustained high rpms are experienced or engine is setup on the lean (best power) side or when a super/turbo charger/nitrous is used.

My experience: one heat range colder plugs showed much to much 'color' after only a few hundred miles; stock heat range plugs with an extended tip gave me the light tan color I was looking fo.

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

theformula

I heard from MSD that the MSD6AL increases the spark and heat so you need a colder plug to compensate. I have stock pistons. Cant I damage them?

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'92 Formula
305 TPI 5speed
1LE package
Mods: SLP headers,SLP catback,SLP air foil,ported plenum,Crane AFPR (47psi),MSD6AL,AC delco cold plugs, Bosch O2sensor, homemade cold air,K&Ns,3:73s,JET fan switch, Macewen white face gauges

JakeJr

Here's basically the way it works.

A plug that is too cold won't hurt the engine, it merely fouls out and makes the engine lose power and run badly, especially at idle and low speed. So if you install a set that are too cold, it won't be long before you'll know it.

A plug that is too hot CAN damage the engine because it will cause pre-ignition and detonation.

Without a lot of expensive monitoring equipment, the best way is to start with the plug recommended by MSD. They should give you a specific heat range plug to use as a baseline.

Find a level, open stretch of road with no traffic or entrances/driveways. Then do a wide open throttle blast in 2nd gear. Cut the engine clean with zero idle time and coast to a stop.

Pull the plugs and look at them to determine their color. The color should be very light tan without any signs of speckles (fly sh*t). If you can get one, use a lighted, magnifying glass and look at the base of the porcelain (the part that's buried behind the threads) and there should be a tan colored ring at the very base.

Brand new plugs may take a little while to show color, but if they show a dark tan or grey, then they are probably too cold, especially for around town driving.

Reading plugs is probably more of an art than a science, so if you're not sure, buy a couple of extras and after a WOT blast, install the new ones and take the ones that were in the engine during the blast to someone who knows how to read them.

Hope this helps.

Jake


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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9