if you buy the ACS23CC's you'll see they're longer than the AGS42CC's, the 42s are petrol engine plugs, the standard plugs for the I6, it's all i can say mate, i've held the 2 together in my hand and i can tell you the gas plugs are longer, the spare parts bloke called them projected gap plugs

they made a huge difference to starting my car, the stock plugs were fitted when i 1st bought it, it was a real prick to start, it went back 4 times to try and fix this problem, they never really did fix it and i thought it must be just how duel fuel engines are ... when it came due for it's 1st service after the warranty expired, i bought the plugs listed in the tickford supplement, the 43's ... when i pulled the plugs out that were in the car i could see the new ones were longer, i double checked the part number, didn't want the tip of the plug hitting the top of the piston, yes it was the right plug in the tickford manual .... i stuck em in, crossed my fingers when i cranked it over, it fired up immediately, easiest it had ever started ... drove to the ford dealer and told the service manager what i'd found out (that they had fitted the wrong plugs) he wouldn't believe me, i told him, you go out and start it mate then come back and tell me i'm worng ... he wouldn't do it, just made excuses to not go out and see for himself

so, you see that's how i know i'm right, they are longer than the petrol plugs, take my word for it

Doesnt suprise me, the autolite 985's were noticibly longer than the plugs I pulled out (I assume they were from Ford as they were starting to look a bit old at the time)

Wouldn't the longer tipped plugs be hotter running. For the LPG you would have to go colder plugs.
The understanding is the hotter plug would burn the mixter better but the motor would run hotter on a long trip.

The old E49 Chryslers & XU1's ran a colder plug.

I've had the NGK iridum's in for over 50,000 K's no problems. Still like new as they can withstand higer combustion temps

ghiaman

stuff about heat ranges and projected gap spark plugs

"Projected-Nose Gap: Projected-nose spark plugs can be used in any overhead-valve engine provided there is physical clearance in the combustion chamber. The heat-range characteristics of this spark plug differ from other spark plugs in that the incoming air/fuel charge cools the insulator tip at high engine speeds, preventing fouling that can be caused by excessively rich mixtures."

and

"Heat Ranges: The thermal characteristics or "heat rating" of a given spark plug reflect the component's ability to transfer combustion-chamber heat from the firing end of the spark plug into the cylinder head. The range of temperatures from idle to maximum rpm determines the heat range of the spark plug. From a design and construction perspective, the length of the insulator nose determines the heat range of the spark plug."

and

Heat Ranges, More: Cold spark plugs normally have a short heat flow path, which results in a quick rate of heat transfer. Additionally, the short insulator nose found on cold spark plugs has a small surface area, which does not allow for a massive amount of heat absorption. On the other hand, hot spark plugs feature a longer insulator nose as well as a longer heat transfer path. This results in a much slower rate of heat transfer to the surrounding cylinder head (and, consequently, the water jacket)."

there ya go

http://corvettefever.com/techarticles/153_0503w_plug/

Question: What is the difference between a hot spark plug and a cold spark plug?

Answer: A "hot" spark plug will have a longer ceramic insulator in the center of the plug than a "cold" one. On occasion, we have installed hotter spark plugs in an engine that uses oil. The hotter plug burns the oil off and keeps the plugs from fouling.

http://www.2carpros.com/topics/sparkpl.htm

yet more

http://www.google.com.au/search?hl=en&q ... arch&meta=

would that be the same plug for a xr6 as well?

seems as id they supply the 985's to all cars but im tempted to try the AP63 see what jmm has to say about them

just bbought some ngk iridiums .im going to try them in the xr see how they go

finally found a dealership in sydney that had these Autolite things put them in gave to car a bootful yeah i could vouch for a couple of kw.

where did you find them 99

You're doing yourself a big dis service by going for "low resistance" leads. It's complete s**t.

Check out the magnacor website. They set the record straight.

I hear you but I have put High performance Bosch leads on which are way lower in resistance than the ford originals, Oh, btw I am an Electrician so I know what you mean.