What spark plugs for a 292 HEI setup?

[mahanian]

The PO of my 67 swapped out the distributor for a HEI setup on my 292, but he kept the original plugs. I thought I should upgrade the plugs to the same ones that the mid-70's HEI 292 trucks are running, but the spark plugs aren't similar at all. I did a little research and it turns out that in 70 all of the 292 spark plugs changed to the same ones that the V-8's run. My question is does anyone know if they changed the head on the 292 in 70? I know it changed in 75 to the integral head, but I wasn't aware of any changes before that. The plugs for the 70+ 292 aren't as long so I'm worried that the electrode won't be down in the cylinder chamber.

Anyone have any thoughts on this?

[68gmsee]

On my 68 with 250 six, I used the recommended plugs but opened up the gap to .040. Some suggest opening up the gap to .045.

[ed2552]

Yeah, use the recommended plugs and open the gap a little.

[70c/10barebone]

Having just completed the HEI upgrade yesterday in my 70 250 I think I can help. I got plugs and wires for a 79 250 and after pulling my old plugs they were noticably shorter then the new ones. I got online and did a part search(1970 vs 1979) and found overlapping part numbers on the highest priced plugs but different numbers (although equal reach lenghs) on the budget ones. This may be do to different temp ranges. I concluded my old plugs were just shorter then necessary. And after putting in the new ones everything is running great. I think you'll be good either way.

[Wrenchbender Ret]

The earlier heads used a lomger plug with a flat surface & gasket. The later head used the tapered seat plug & was shorter. You must use the correct plug. You can open the gap to .045 for HEI. The heads are basically the same except for that & about 67 up had the temp. sensor in the head. About 68 up they had openings for emission control air injection. The intergal intake was not used on 292's.

[mahanian]

Thanks for the info, that helps out a lot!

[newbraunie]

I am running standrd plugs at .45" gap because I had just purchased them prior to HEI conversion and it runs great.I purchased my HEI set up from Langdon Stovebolt. In the instructions provided they recommend the following.

Switch out spark plugs to extended tip design, designated by "Y" suffix on Champion or "S" suffix on AC delco. These plugs are designed to be gapped at .60"-.80". This will provide hotter spark than standard plugs. Result is better idle and low speed driveability.

[mahanian]

Originally Posted by newbraunie

I am running standrd plugs at .45" gap because I had just purchased them prior to HEI conversion and it runs great.I purchased my HEI set up from Langdon Stovebolt. In the instructions provided they recommend the following.

Switch out spark plugs to extended tip design, designated by "Y" suffix on Champion or "S" suffix on AC delco. These plugs are designed to be gapped at .60"-.80". This will provide hotter spark than standard plugs. Result is better idle and low speed driveability.

I'll look into it, thanks!