Recommend me some spark plugs

[SUX2BU99]

It's time for some new plugs. I think the ones I had were stock heat range. The use for my truck is nice days, weekends and occasional drag strip blasts. It weighs about 4000 lbs and runs high 14s. Motor specs are below. Thanks for the help!

85 Chevy Silverado C10 short, wide, yellow, 2wd, Lowered.

60-over 350 with Dart Iron Eagle heads (165cc, 1.94/1.50) and Comp Cams XE268 cam, Mallory HEI, Aurora 8mm wires, Edelbrock 1406 carb, Dart II Sportsman dual-plane intake, full-length headers.

TH350 w/ shift kit, 3.40 Gov-lok 12 bolt.

[SUX2BU99]

Oooookay, maybe not then.

I was reminded that the head manufacturer I used (Dart) recommends an Autolite AR133. That's a racing plug (ie. expensive and not easy to find) and is also a 'cold' plug. The AR134 would be better (warmer) and I believe I have Accel equivalents to that. I found a great comparison page on Jegs website:

http://www.jegs.com/PDFs/111-UGroove.pdf

Trying to track down any kind of equivalent isn't proving too easy either.


I guess I could try a stock range plug. My engine isn't too terribly radical but I don't know if stock-type plugs are the same dimensions as the ones recommended for my heads (.460" reach, standard tip, tapered seat, 5/8 nut and 14mm thread).

I was told about the Autolite 26 plug. I looked it up and it seems to be quite a universal spark plug and looks to fit applications for basically any GM straight 6, small or big block  V8 made in the 70's to late 80's.

[joesgarage71]

 Nobody answered cause its hard to figure out plugs from the speed parts you have.  Trail and error. AC 44 is stock they use 43's in big blocks. one step colder. you have MORE compression and cylinder pressure than stock. Them 26's sound about right or try a set of 25's. your building more heat in the cylinder so a colder plug gapped at .035. Even though you have a HEI and stock they are like .050-.060 plug gap. you just have to play with it. See what it likes.

 My 92 has a 90 Big Block in it and the PO had the plugs gapped at .045. I regapped them at .035 and seen a pick up in mileage. Just an example every engine wants some different.

I hope this helps

[VileZambonie]

Try these http://www.jegs.com/i/NGK%20Spark%20Plugs/739/R5674-6/10002/-1?CT=999

[Blue 82]

I made the switch to NGK
these are what I run
NGK UR4 - most auto parts stores have em in stock
http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&N=0&Ntk=all&Jnar=0&Ne=1%2B2%2B3%2B1147708&searchTerm=ur4

NGK heat ranges are different from champion etc....
the lower the number the hotter the plug
http://www.ngk.de/Spark_plugs.649.0.html

[malibu795]

i run ac delcos RT43T in both my engines

[SUX2BU99]

Thanks guys. I went with the Autolite 26's for now. Gapped them at .040. I checked the Accel 577's I took out and they weren't even at .035. Closer to .030 probably. My #6 was quite dark compared to the other cylinders. I broke the new #2 tightening it    And #5 really fought me putting it in but my headers was the cause of that problem. So they are all in. Haven't run it yet but hopefully this weekend I will.