I bought my car used and I have no idea when the last time the plugs were changed so I am gonna go ahead and change them. What kind should I get??? 305 TBI with mods in the sig....

 

standard AC Delco plugs, 89 cents each.

 

Ditto. Don't buy into the hoopla with big dollar plugs. I have run expensive plugs that I have had to change within 2000 miles. If anyone starts a plug debate I will close this thread. It has already been covered a trillion times.

 

So there is no advantage to running more expensive plugs?? Sweet, saves me some money

 

I just got the AC Delco Rapid Fires. A little bit more exspensive than the normal ones, but I dont have a single complaint about them yet!

 

You only need to spend money on plugs when you need somthing other than stock for power adding situations.

 

Yea, for NA Id stick with the Delcos. I run them and using more expensive ones, didnt notice a difference. Spend the extra money on a good set of wires, that'll be a better investment. or a case of Busch Light

 

Yeah your best bet is to run AC Delco. When GM built there engines, all the testing was done using AC Delco. For compatibility reasons, OEM would be your best bet.

 

The part number for the AC Delco's are R45TS, if you want to know.

 

Do you think the AC's last as long as the platinums? Don't want to start an argument but the plugs are a pain to change.

 

Funny you should ask. Platimun plugs get either awesome reviews or horrendous ones for our cars. They tend to foul out with an aftermarket coil. Our HEI systems produce a lot of juice and tend to increase the corrosivity of platimun. I had a set fould out in 2k miles. Others have seen 80K. I would put my money elsewhere and just run the plain jain AC delco. I bought into the gimmic with $50 plugs and was really sorry when the car idled like poo after 2k miles.

 

They will probably last just as long or longer than the platinums. Just stick with the AC Delcos.

 

dont waste your $ on the bosch platinum plugs i have them in my camaro they dont help one bit, plus instead of spending 89cents each you spend $6.99 each, i feel like an for buying these, i will however be buying some delco plugs very soon. the engine idled great with the stock plugs when i put these in-it idled like crap i dont have 20miles on the rebuilt engine and it sounds like ****

 

i just changed my plugs about a month ago with the AC Delco's and i couldnt be happier. also seemed pretty easy to change. its extreamly easy if you can get at them from under the car. from the top they would seem damn near impossible.

 

Eh, kind of depends. Some were easier to get from up top, and some were easier to get from the bottow. Sometimes you really dont have much of a choice

 

I've got Bosch Platinum +4's in mine and don't have any complaints about them yet. Probably not worth the money though.

 

Those are the ones that I ran for such a short amount of time before they peaced out on me.

 

Basically, high-performance spark plug selection can be boiled down to four basic steps: Pick a shell design, choose an electrode gap style, determine preliminary heat range choice, and evaluate the preliminary selection in the car or on a dyno.

Shell Design

Most custom-built engines no longer have original cylinder heads—so the first thing you need to do is figure out the necessary spark plug thread diameter, thread length or “reach,” and the type of seat design required by the currently installed heads. Failure to select the right plug can result in inconsistent heat range and potential engine damage.

Some heads may accept several different shell designs. This can be important if you have a header clearance problem, or if the proper heat range is not offered in every shell. It pays to become familiar with your favorite plug maker’s catalog offerings and available heat ranges.

The porcelain end of today’s standard plugs is longer than that of equivalent plugs from the classic musclecar era. This may result in plug or plug wire interference on older headers. Possible solutions include shorter “lawn mower” plugs or special “shorty” plugs available from ACCEL and other manufacturers. Note that lawn mower plug heat range availability is extremely limited.


Electrode and Gap Design

When selecting the spark plug “nose” configuration, the simple rule to remember is: The more the spark plug is exposed to the air/fuel mixture, the easier it is to initiate combustion. Many specialized plugs have been developed for high-end race cars, but for most dual-purpose vehicles the choice typically boils down to either regular-gap (conventional) or projected-nose styles.

The regular-gap plug is the traditional configuration factory-installed on many classic musclecars. For modern high-performance work, it should only be used if there isn’t enough clearance for a projected-nose plug. The latter style “projects” the spark further into the chamber than a standard plug, and will nearly always offer improved performance if there is sufficient valve and piston clearance, although many nitrous oxide users prefer to stay away from them because of excessive heat buildup in the tip that can cause detonation.

Projected plugs initiate the flame-front closer to the center of the combustion chamber, which has an effect similar to advancing the timing. This lets the total ignition advance be reduced, decreasing the chances of detonation while providing superior throttle response. A projected plug’s longer core nose provides a hotter plug at low speed to help prevent fouling. As engine speed increases, the incoming air/fuel mixture flows across the core nose tip, providing charge cooling that effectively reduces the heat range for increased top-end detonation resistance. Today many race cars also used projected-nose plugs, albeit in highly modified form from the “civilian” versions—the ground electrodes are often cut back to help improve the flame kernel and reduce the voltage amount needed to fire the plug.

Heat Range

Controlling the operating temperature of the plug’s firing tip is the single most important factor in spark plug design. “Heat range” is the relative temperature of the spark plug’s core nose, and it is determined by the length and diameter of the insulator tip, as well as the ability of the plug to transfer heat into the cooling system. A “cold” plug transfers heat rapidly from its firing end into the cooling system and is used to avoid core nose heat saturation where combustion-chamber or cylinder-head temperatures are relatively high. A “hot” plug has a slower heat transfer rate and is used to avoid fouling under relatively low chamber or head temperatures. What’s confusing is that a “hotter” (higher performance level) engine requires a colder plug because more power equals higher cylinder temperatures.

 

Running stock Delcos for the first time since the orginals I agree. AC DELCO R45ts all the way.
For some reason they seemed quicker to remove and replace than my previous sets of plugs, bosch, autolite, etc. I believe it has to do with the external shell design after reading adambros' post. (maybe I'm getting better changing them.)

Anecdotal experiences are best left as a loose guide when it comes to engineering though.

 

the only thing i like about those (+4) plugs are that they are just a little bit shorter then the delco's which makes it ideal to get them in-around tight headers and cramped spaces, but seeing how theres lots of room on my engine the plugs could an extra 1" longer and they'd still fit.

 

sorry for being a stupid car n00b, but... how can i tell if i need new spark plugs, my car runs ok, starts up. Im sure they need replacing, i havent even seen them.

But... What sort of diffrence can a person notice in their car from changing their plugs ???????

 

You want to make sure that your plugs are not all gummed up with carbon. You also want to make sure they are not completely white or completely black. You want to check the sides for cracks and such. last but not least you need to check that the electrode (the prong hook thing that the spark comes off of) has not been burned down to nothing. If you have worn out plugs, new ones will add smoother idel, better mileage, and greater throttle response.

 

thanks...

funny you say that , i was just thinking about how slow my throttle response is on my gas....

and again, sorry for being the idiot on the fourms, but how exactly, and what tools do i need to change the plugs.... ( nobody in the family is/was ever into cars, have no one to show me )



edit: nevermind, --- the many uses of the search button....


though i just ran outside to check, and it seems to be the spark plugs are at the bottom middle of the engine, do i have to jack the car up to get to them ?

 

I run ac R45TS, and thats about all I can run, My ingition soysem is 100 precent MSD, and with a 6AL box, and all othe other goodies, you cant run platnum. I dont mind though costs me about 10 bucks everytime I change plugs though

 

You can change some from the top and the rest from the bottom. You need a deep well 5/8" socket. It is a pain to do but you can buy one of these modifed spark plug sockets on ebay that makes things so easy.