Question For Dave Ray (Astro Van Plug Gap)... - Chevelle Tech
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post #1 of 9 (permalink) Old Oct 17th, 19, 4:45 PM Thread Starter
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Question For Dave Ray (Astro Van Plug Gap)...

I looked under the hood of my mom's Astro van this morning. I glanced at the emissions sticker, and it shows the plug gap at .060. I don't know if the distributor in this vehicle (2000 model year) is considered to be an HEI. Would running the gap at .040 - .045 be better for this particular ignition system?? It uses a 'corrected' cap (1,3,5 off of the driver side, 2,4,6 off of the passenger side of the cap). The aftermarket caps have a bad habit of developing hot spots, which leads to cross firing (engine runs poorly, backfires, etc.). So, I am just wondering if the plug gap should be reduced.

1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #2 of 9 (permalink) Old Oct 17th, 19, 5:26 PM
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Re: Question For Dave Ray (Astro Van Plug Gap)...

gap the plugs at .040 to .045 max. wait for ray to chime in but I bet he says the same thing
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post #3 of 9 (permalink) Old Oct 17th, 19, 5:45 PM
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Re: Question For Dave Ray (Astro Van Plug Gap)...

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Originally Posted by gnicholson View Post
gap the plugs at .040 to .045 max. wait for ray to chime in but I bet he says the same thing
That's exactly what he'll say. He said that about a week ago in another thread.
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post #4 of 9 (permalink) Old Oct 22nd, 19, 10:31 AM
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Re: Question For Dave Ray (Astro Van Plug Gap)...

I just replaced one of those crab caps in my 4.3 Blazer. It was about 6 years old and a Delco. Clue? started running really bad. doing the usual shade tree checks, pulled the plug wires off one at a time. When I pulled off the wire to #5 the engine speeded up and smoothed out? huh?!? then I remembered the cap had the bars criss-crossing to make the plug wires come out neatly. problem solved. cap looked perfect inside and out.
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post #5 of 9 (permalink) Old Oct 22nd, 19, 3:18 PM
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Re: Question For Dave Ray (Astro Van Plug Gap)...

Those vans run .045 maximum spark plug gaps. The .060 was set by emissions techs trying to get a larger spark area to light off a fuel molecule that was less/leaner than earlier .045 gap systems. In these years, GM had to warrantee replace massive amounts of both coils and modules because of the .060 and .080 spark plug gaps that emissions techs insisted they needed to fire the popcorn fart lean mixtures off. Changes to the EFI systems and programming took care of the too far open gaps, plugs went back to a reasonable gap, and the world rotated right again.

When that van was supposed to go back for dealer servicing, the plugs should have been re-gapped down to .045 maximum, and a new emissions specs sticker should have been installed, obviously, it didn't get any of that. If it didn't tear a coil/module up, you are very lucky, indeed.

The throttle body EFI 4.3 engine in my 1986 Safari has an emissions sticker that shows a spark plug gap for that feedback EFI module (8 pin), at .035.

With those distributor caps, a story, true, but, tells it like it is. GM didn't design, nor start them, a company called "Cross Fire Caps" did, years before GM. They made caps for GM point distributors, and inside them, to move spark from one side of the cap to the other, they used a magnetic suppression, spiral core section of spark plug wire, nice stuff, the caps were good quality, worked, lived long lives and prospered. One day, owner of the company decided to retire, and sold the company to, whom else, a person only interested in profit margins, high ones. New "engineers" came into play at the new business, and they changed the cross over media, from the good spark plug wires, to the much easier to do, and seriously less expensive PRINTED CIRCUIT media. Cap quality went from great, to worst in the industry ASAP with the change.

GM "engineers" working on their cross over ignition project didn't have enough common sense to pay attention, and designed the stock cross over caps with UN-INSULATED PRINTED CIRCUITS. Instant junk. What Tom experienced with cylinder 5, was the ignition system attempting to fire off two separate spark plugs at the same time, because of RF energy transfer from one printed circuit plug "wire", to another inside the cap, to fire BOTH plugs at the same time. Probably one cylinder firing when it should have, another firing too early, both of them fighting each other.

Same basic thing happens when a really bad set of RF leaking spark plug wires are run together on an engine along side and inline with each other. This is why we need to run a GOOD set of magnetic suppression, spiral core wires, 8mm if possible, on any and all of today's ignition systems, and not run them parallel with each other, cross them over each other, form an X.

OK, what else did all you guys do, this is getting fun...again.
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post #6 of 9 (permalink) Old Oct 22nd, 19, 8:13 PM Thread Starter
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Re: Question For Dave Ray (Astro Van Plug Gap)...

Thanks for chiming in, Dave. My mom bought the van used back in 2001, and it never went to the dealer for a tune up. So, one of these days (when I need to swear some more), I will think about pulling the plugs and regapping them.

1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #7 of 9 (permalink) Old Oct 22nd, 19, 10:42 PM
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Re: Question For Dave Ray (Astro Van Plug Gap)...

It works a lot easier if you pull th engine cover off. There are two clamps on the bottom rear of the covr, and look under the hood, might be two bolts up at the top of the cover than unscrew towords the front of the vehicle. That's the way mine is, might be the same for yours. Pass and driver seats back as far as possible, as well.
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post #8 of 9 (permalink) Old Oct 22nd, 19, 11:10 PM Thread Starter
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Re: Question For Dave Ray (Astro Van Plug Gap)...

Quote:
Originally Posted by Dave Ray View Post
It works a lot easier if you pull th engine cover off. There are two clamps on the bottom rear of the covr, and look under the hood, might be two bolts up at the top of the cover than unscrew towords the front of the vehicle. That's the way mine is, might be the same for yours. Pass and driver seats back as far as possible, as well.
I've had the engine cover off many, many times. I actually just pull the passenger side seat out and move it out of my way (4 nuts - takes less than 5 minutes).

1971 Malibu, factory buckets/full gauges/console, 377 roller cammed small block, Turbo 400, 3.42 10 bolt posi (Buick), - All your base are belong to us.
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post #9 of 9 (permalink) Old Oct 23rd, 19, 1:43 PM
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Re: Question For Dave Ray (Astro Van Plug Gap)...

Aha, "Option 2" pull the pass seat. My van that I use for most things hasn't had its pass front seat in place for 7 or so years, makes for a lot more room to move stuff, get the engine cover off, etc.
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