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#1 |
Registered User
![]() Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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spark plug gap with HEI dizzy
If I have an HEI distributer should I have a bigger gap in the plugs than if I had points? I think my newer trucks with HEI plugs were pre gapped at something like 45 but if I remember right old point stuff was like 24. My trucks had an HEI for a while but as I was about to put in the plugs today it occurred to me that I had never thought about that before and just put in what I was given. If it should be a bigger gap what should that be? Can anybody tell what the difference would be? thinking it will be a hotter spark jumping a larger gap but....?
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#2 |
Registered User
Join Date: Jan 2009
Location: Calgary, AB
Posts: 1,181
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Re: spark plug gap with HEI dizzy
0.045 is a good setting for hei
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#3 |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,222
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Re: spark plug gap with HEI dizzy
If I recall a pinch more than what it would otherwise be for your points.
Now if I could just remember what my timing should be.
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 06-03-2015 at 12:38 AM. |
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#4 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,621
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Re: spark plug gap with HEI dizzy
Yup -- .035 for points, .045 for HEI.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#5 |
Registered User
Join Date: May 2015
Location: Jacksonville NC.
Posts: 10
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Re: spark plug gap with HEI dizzy
As with everything its about the sweet spot. The benefits to bigger gap is that it ignites the fuel quicker, resulting in faster, more reliable starting and a more powerful burn. but too big and you can burn up your coil or even cause a misfire. A standered HEI is 35,000 volts and should be set at .45 spark plug gap. Whats the output on your coil?
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If it works, don't fix it. |
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#6 |
Registered User
![]() Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: spark plug gap with HEI dizzy
Should just be stock standard. It just the factory coil in the top of the cap.
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#7 |
Account Suspended
Join Date: Jan 2007
Location: Tucson
Posts: 2,183
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Re: spark plug gap with HEI dizzy
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#8 |
Registered User
Join Date: Feb 2015
Location: Morganton, NC
Posts: 108
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Re: spark plug gap with HEI dizzy
yeah .038 is what O'reileys quoted me when I put in a set of AC Delco plugs just a few weeks back.
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Better to remain silent and be thought a fool than to open your mouth and remove all doubt. - Mark Twain |
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#9 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,250
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Re: spark plug gap with HEI dizzy
Don't assume any plugs are ''Pre-Gapped''. A good thump on the loading dock, and a gross of plugs are all out a couple thousandths.
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Every 25 years I like to rebuild that 292, whether it needs it or not. |
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#10 |
Registered User
Join Date: Jul 2010
Location: MD
Posts: 1,937
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Re: spark plug gap with HEI dizzy
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#11 |
Registered User
Join Date: Feb 2012
Location: So. Cali.
Posts: 2,642
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FWIW ;
Back when HEI was a new thing in 1975 , GM told us to use .060" . It turned out this made the engine run GREAT but chewed up rotors and caps pretty quickly so the decided .045" was a good middle ground . My 1969 C/10's 250 CID i6 burns a quart of oil every 150 miles and fouls plugs to missing by 200 miles so I added an stock HEI and began experimenting with plug gaps ~ I now run .070" and have no smoke , little burned oil smell and don't foul the plugs any more . So far the Junk Yard 1977 HEI has help up just fine , over 20,000 daily driven miles sans problems . Even breaker points ignitions should be gapped to .035" , you'll feel the power .
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-Nate Geezer '49 3100 235 W/ Muncie SM420 SOLD '69 C/10 shortbed sidemount survivor 250 L6 W/ 350TH ![]() |
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#12 |
Registered User
Join Date: Jul 2012
Location: Ft Wayne Indiana
Posts: 1,204
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Re: spark plug gap with HEI dizzy
I'm running .045 on mine.
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71 K20 64 GMC mud truck |
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#13 |
Registered User
![]() Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: spark plug gap with HEI dizzy
I just set them at 45 and put them in so I hope that will be fine. I going to post another thread about what wires do I need to get to be long enough as in application not brand . I cant go to the auto zone and buy wires for my 71truck with HEI cause it didn't come with that.
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#14 |
Registered User
Join Date: Jul 2010
Location: MD
Posts: 1,937
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Re: spark plug gap with HEI dizzy
Wires for a '75 should work. First year HEI was standard equipment.
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#15 |
Registered User
Join Date: Oct 2009
Location: canton ga
Posts: 12,728
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Re: spark plug gap with HEI dizzy
This is very useful info guys ,thanks as I needed to ask that very question.
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#16 |
Registered User
![]() Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: spark plug gap with HEI dizzy
For the record the question asked and answered in another thread I posted is 75-78 corvette wires, HEI and long enough to go around the back and under the manifold like factory original .
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#17 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,250
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Re: spark plug gap with HEI dizzy
I usually get the Accel 8mm wire in trim-to-fit.
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Every 25 years I like to rebuild that 292, whether it needs it or not. |
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