What spark plugs for a 292 HEI setup? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mahanian · 06-12-2009, 12:24 AM

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 · 06-12-2009, 09:20 AM

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 · 06-12-2009, 10:08 AM

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

70c/10barebone · 06-12-2009, 11:23 AM

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** · 06-12-2009, 05:25 PM

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 · 06-12-2009, 05:29 PM

Thanks for the info, that helps out a lot!

newbraunie · 06-12-2009, 05:42 PM

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 · 06-12-2009, 06:03 PM

Quote:

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!

06-12-2009, 12:24 AM	#1
mahanian C10 addict Join Date: Apr 2006 Location: Arizona Posts: 2,432	What spark plugs for a 292 HEI setup? 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? __________________ Jared 67 C10 CST Short Fleet Big Window 65 C10 Custom Short Fleet Big Window 67 Camaro RS

06-12-2009, 09:20 AM	#2
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: What spark plugs for a 292 HEI setup? 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.

06-12-2009, 10:08 AM	#3
ed2552 Registered User Join Date: Jan 2007 Location: Charles City IA Posts: 1,626	Re: What spark plugs for a 292 HEI setup? Yeah, use the recommended plugs and open the gap a little. __________________ '67 C20, Under the Knife!, LWB, Eaton HO-52, Rear Coil Springs 72' GMC C2500, 350, TH400(?), Dana 60 '67 K10 4-spd., 305, SM465, Dana 44, 12 Bolt, RUST! '65 C60 292, 4 spd, 2 spd Rearend, 15' Grain Box, MINT! 09 Yukon Denali 82k Miles 6.2L/6A

06-12-2009, 11:23 AM	#4
70c/10barebone Junior Member Join Date: Oct 2006 Location: Lawrence, KS Posts: 79	Re: What spark plugs for a 292 HEI setup? 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. __________________ 70 C/10 LWB 250 Last edited by 70c/10barebone; 06-12-2009 at 11:26 AM.

06-12-2009, 05:25 PM	#5
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,194	Re: What spark plugs for a 292 HEI setup? 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.

06-12-2009, 05:29 PM	#6
mahanian C10 addict Join Date: Apr 2006 Location: Arizona Posts: 2,432	Re: What spark plugs for a 292 HEI setup? Thanks for the info, that helps out a lot!

06-12-2009, 05:42 PM	#7
newbraunie Registered User Join Date: Aug 2008 Location: Central TX Posts: 393	Re: What spark plugs for a 292 HEI setup? 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.



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