Spark Plug Recommendations

ryan_thompson87 · July 4, 2007

Ive been wondering what I should be running for spark plugs, as I think thats whats causing my idle and driveabilitly problems. I think I need a higher heat range. The motors a 355 with about 9.6:1 compression, Vortec heads, GMPP TBI Vortec Intake, A Mild Cam, and headers. It idles like crap and surges abit going down the road. Sometimes there is a misfire also.

Genuinefine409 · July 4, 2007

Ive been wondering what I should be running for spark plugs, as I think thats whats causing my idle and driveabilitly problems. I think I need a higher heat range. The motors a 355 with about 9.6:1 compression, Vortec heads, GMPP TBI Vortec Intake, A Mild Cam, and headers. It idles like crap and surges abit going down the road. Sometimes there is a misfire also.

Stock plugs should be fine for your setup. What plugs (name and number) do you have? Surging while driving can sometimes be associated with a lean fuel mixture as well. What plug wires do you have? Did you put plug grease on them? I had a few experiences where it was sparking past the plug and hitting the block and causing a similar problem to what you’re having. Best way to check for this is at night or in dark garage, run engine and watch around the plugs to see if you see any arcing. I'd also check the resistance of your wires. Good performance wires should not be over 1500ohms per wire. Race wires can be as low as 100ohms a wire but that is not necessary for what you’re doing.

I've used stock AC Delco plugs on my race motor which is a 355 Vortec and that is over 500hp and 12:5 compression. I used an NGK plug now because it’s hard to find a non-projected tip plug for the Vortec heads deeper threads.

Also, and most important, what do the plugs look like? The best way to determine a plug or fuel adjustments is by reading the plugs.

ryan_thompson87 · July 4, 2007

Right now Im running Delco 41-601s and the truck is over fueling and it is ruining the plugs my main question is if a hotter plug will burn it better.

Genuinefine409 · July 4, 2007

Right now Im running Delco 41-601s and the truck is over fueling and it is ruining the plugs my main question is if a hotter plug will burn it better.

It could. You shouldn't have to move up more than 1 or 2 heat ranges. If you do and it doesn't clean the plugs up the problem is somewhere else. I would try plug #41-932 (or Autolie #605)first. That is what a 96 5.7 Vortec calls for. That is what I used in my race motor for a long time. They are expensive though, over $5 per plug, you can get Autolite #605 for like $1.5 a plug. They are basically the same plug as far as heat range except the Delco is a Professional Platinum. What do you have your gapped at? Do you have any ignition box or anything?

ryan_thompson87 · July 4, 2007

Stock Ignition and gapped at .40

Genuinefine409 · July 4, 2007

Stock Ignition and gapped at .40

I would try the Autolite plugs #605 gapped at .40, if you feel you want a hotter plug then try #606. You want to run the coldest plug you can without it fouling out for best performance. typically when you start increasing an engine's output, especially increasing compression, you need to use a colder plug but you're plugs might just be too cold. try the 605's or 606's, they should put you were you want to be.

mcreyaufmiller · July 16, 2007

I am assuming from your handle that your truck is a 87? My next question would be do you have a computer running this system? What was the old motor in the truck? The reason I am asking these questions is because I ran into some of the same issues when I did my swap. The computer had to be reprogrammed for the new motor and is still in need of some fine tuning. Currently, I get small surges or "seeking" which is the computer trying to find an idle spot, but lacks enough idle air to smooth out. So it opens the blade a little and the RPM's increase and you get a surge.

etex211 · July 17, 2007

I've had several vortec headed motors in my dirt cars in recent years. I ran those heads on both 355's and 406's. I always used Champion RS12YC plugs and never had any problems.......

The Champion S series is a projected nose like the Vortec head needs. The 12 is roughly equivalent to an AC 43. If you need a hotter plug, then the proper Champion would be a 14, 15, or 18.

I switched from AC plugs to Champion plugs about 14 years ago when I had some plug fouling problems. I've never fouled a Champion.

The stock number for the RS12YC is 401. RS14YC is 408.

Hope this helps.

Genuinefine409 · July 18, 2007

I've had several vortec headed motors in my dirt cars in recent years. I ran those heads on both 355's and 406's. I always used Champion RS12YC plugs and never had any problems.......

The Champion S series is a projected nose like the Vortec head needs. The 12 is roughly equivalent to an AC 43. If you need a hotter plug, then the proper Champion would be a 14, 15, or 18.

I switched from AC plugs to Champion plugs about 14 years ago when I had some plug fouling problems. I've never fouled a Champion.

The stock number for the RS12YC is 401. RS14YC is 408.

Hope this helps.

Just curious if you have used the new Vortec Bowtie heads? I have a few buddies that use them in dirt track racing. I am having a tough time finding spark plugs with a non-projected tip. The domes on my pistons don't like them and my circle track buddies all use flat tops so no worry. Anyone know of a good non-projected tip plug for vortec heads(thats cold)?

etex211 · July 18, 2007

Genuine, I haven't tried the Vortec bowties.....don't really know much about them. I'm in a class now that only allows us to run open chamber heads, such as the 441, 487, or 993.

There is a lot of good information in the Champion catalog, if you can get a hole of one. When I made the switch, I got them to send me one, so I could learn their numbering system. If you call those guys, maybe they'll send you one. I'll bet you could find what you need in there.

It really helps to know the exact plug number you need when you walk into the parts store, instead of trying to have them look it up for you.

Genuinefine409 · July 19, 2007

Genuine, I haven't tried the Vortec bowties.....don't really know much about them. I'm in a class now that only allows us to run open chamber heads, such as the 441, 487, or 993.

There is a lot of good information in the Champion catalog, if you can get a hole of one. When I made the switch, I got them to send me one, so I could learn their numbering system. If you call those guys, maybe they'll send you one. I'll bet you could find what you need in there.

It really helps to know the exact plug number you need when you walk into the parts store, instead of trying to have them look it up for you.

thanks I will see if i can get a catalog from them. its difficult to get most big chain parts strores to look stuff up. If they don't have their computer to tell them what they need most of them can't look in a book. I'm glad there are a lot of local parts store in my area i can deal with. thanks again.

ryan_thompson87 · July 29, 2007

Sorry Been Away For Awhile. Yes The Engine Is A TBI Motor, And Is In Need Of A Tune. A leaking injector was the main cause of my pig rich scenario, and a thottle body spacer helped, but did not completley eliminate, at 4 grand it starts to pour black like a deisel. Yikes.