Home » Public Forums » GMCnet » Dollar-bill Test
| Dollar-bill Test [message #352485] |
Fri, 28 February 2020 13:02  |
uprooted
Messages: 72
Registered: December 2019
Location: Hilliard, OH
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I was excited to find that the "official" engine health checks on our 455 seem to be great... good oil pressure, compression @150 each cylinder, 40+ cm Hg, and hand holds perfectly steady on vacuum gauge. However I've discovered that it fails the "dollar bill test". When you hold a piece of paper very close to the exhaust pipe, the paper will slap against the pipe. It is erratic in how often it happens. Ranges from once every 2 or 3 seconds to several times per second. The implication here is that one or more exhaust valves are not seating fully and the intake stroke sucks in some exhaust. How is this possible if the compression test checked out? The 455 has headers and what appears to be factory type exhaust, 2 muffler, y pipe, 2.5" pipe to rear. Exhaust crossover is blocked according to my inspection with a borescope with carb off.
I want to tell myself that the numbers dont lie, but I cant ignore the fact that exhaust gas is moving in the wrong direction momentarily!
Corey P /
Hilliard, OH /
1974 Glacier 26' /
3.70 FD /
ION Wheels
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| Re: Dollar-bill Test [message #352486 is a reply to message #352485] |
Fri, 28 February 2020 13:17  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
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Could be ignition or idle mixture setting. Could be 18436572 pattern with header lengths exaggerating the effect. If it's not an actual missfire and there are no ticks or knocks I would drive it. Remember that 3-5 and 4-6 are not true header pulses as the heads have one port and headers have 2.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Dollar-bill Test [message #352493 is a reply to message #352485] |
Fri, 28 February 2020 15:24 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
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I'd also listen for a miss and feel for a miss. You may think the sky is falling when it isn't. Though all pulses are 90 degrees apart, they do not all alternate banks but 8/4 and 5/7 are clumped on same side banks. Mine runs perfectly and pulses do not feel even with hand over tail pipe.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Dollar-bill Test [message #352499 is a reply to message #352485] |
Fri, 28 February 2020 17:46 |
uprooted
Messages: 72
Registered: December 2019
Location: Hilliard, OH
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It's not just that the pulses dont feel even, it will literally pull the paper up to the tailpipe. I used a plastic bag and it will pull it inside for that millisecond that the suction exists. Is it possible for the normal dynamics of the exhaust system (again with crossovers blocked) to create a momentary suction?
Corey P /
Hilliard, OH /
1974 Glacier 26' /
3.70 FD /
ION Wheels
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| Re: [GMCnet] Dollar-bill Test [message #352507 is a reply to message #352505] |
Sat, 29 February 2020 09:49 |
James Hupy
Messages: 6806
Registered: May 2010
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What Matt said! More'n likely a spark plug, or a wire that leads to it, or
in the case of the GMC, crossfiring plug wires where they run beside each
other. Or, it could be carbon tracking inside the distributor cap, a crack
in the coil, or a faulty rotor. Last, but certainly not least likely, is
too large a spark plug gap. Keep it to .045". NO LARGER THAN THAT.
Lastly, look into the carb, and vacuum lines and that means all of them,
including the factory cruise control.
Jim Hupy
Salem, Oregon
On Sat, Feb 29, 2020, 7:29 AM Matt Colie via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Corey,
>
> You can't see the cross-over from any intake port. If it still has a
> working choke stove, then that port is open.
>
> I would not put too much stock in your dollar bill test with a long
> exhaust system like most coaches have installed. A system that long and
> screwy is
> bound to have some reversion at idle. Did you ever run a 2-stroke with an
> expansion chamber?
>
> I don't put a whole lot of stock in compression tests either. But in your
> case, if any exhaust valve was so badly seated as to cause that reversion
> you are seeing, there would be no compression left in some cylinder.
>
> Drive it and enjoy it.
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
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| Re: Dollar-bill Test [message #352515 is a reply to message #352505] |
Sat, 29 February 2020 22:24 |
uprooted
Messages: 72
Registered: December 2019
Location: Hilliard, OH
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I though of my error after I posted yesterday. I did not see the blocked crossover because the carb was off... it was when I had the choke stove plate off... trying to figure out why the choke was not pulling off when it should. Figured it out! Will probably get an electric choke soon
Corey P /
Hilliard, OH /
1974 Glacier 26' /
3.70 FD /
ION Wheels
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| Re: Dollar-bill Test [message #360939 is a reply to message #352485] |
Fri, 18 December 2020 15:37 |
uprooted
Messages: 72
Registered: December 2019
Location: Hilliard, OH
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This is a super old thread but I thought I'd update for anyone reading here... after getting my timing right, and replacing both mufflers and resonator, this reversion has stopped. It no longer fails the "dollar bill test". Not sure what it was that fixed it but I'm not complaining
Corey P /
Hilliard, OH /
1974 Glacier 26' /
3.70 FD /
ION Wheels
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| Re: [GMCnet] Dollar-bill Test [message #360941 is a reply to message #360939] |
Fri, 18 December 2020 16:45 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
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What is THE DOLLAR BILL TEST?Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: Corey via Gmclist Date: 12/18/20 3:37 PM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: Corey Subject: Re: [GMCnet] Dollar-bill Test This is a super old thread but I thought I'd update for anyone reading here... after getting my timing right, and replacing both mufflers andresonator, this reversion has stopped. It no longer fails the "dollar bill test". Not sure what it was that fixed it but I'm not complaining-- Corey P / Hilliard, OH / 1974 Glacier 26' / 3.70 FD / ION Wheels_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Dollar-bill Test [message #360944 is a reply to message #352507] |
Fri, 18 December 2020 17:18 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
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Thank Jim. I've never heard about it.Sent from my U.S.Cellular© Smartphone
-------- Original message --------From: James Hupy via Gmclist Date: 12/18/20 5:01 PM (GMT-06:00) To: gmclist@list.gmcnet.org Cc: James Hupy Subject: Re: [GMCnet] Dollar-bill Test On vehicles with dual exhaust, a dollar bill is held between a thumb andforefinger on one narrow end of the bill, then dangled in the exhauststream, comparing one side to the other. Not particularly of much value onsingle exhaust vehicles. Very subjective to interpretation as well. If youdid have a collapsed muffler, the thought would be that the bill would movemuch less on that side. For what that is worth, I guess. If the crossoverpassage in the heads and intake manifold, it might be more definitive. Ihave never used it. Other folks may have different results.Jim HupySalem, OregonOn Fri, Dec 18, 2020, 2:46 PM 78gmcroyale via Gmclist wrote:> What is THE DOLLAR BILL TEST?Sent from my U.S.Cellular© Smartphone> -------- Original message --------From: Corey via Gmclist gmclist@list.gmcnet.org> Date: 12/18/20 3:37 PM (GMT-06:00) To:> gmclist@list.gmcnet.org Cc: Corey Subject: Re:> [GMCnet] Dollar-bill Test This is a super old thread but I thought I'd> update for anyone reading here... after getting my timing right, and> replacing both mufflers andresonator, this reversion has stopped. It no> longer fails the "dollar bill test". Not sure what it was that fixed it but> I'm not complaining-- Corey P / Hilliard, OH / 1974 Glacier 26' / 3.70 FD /> ION Wheels_______________________________________________GMCnet mailing> listUnsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org> _______________________________________________> GMCnet mailing list> Unsubscribe or Change List Options:> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org>_______________________________________________GMCnet mailing listUnsubscribe or Change List Options:http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Dollar-bill Test [message #360945 is a reply to message #360941] |
Fri, 18 December 2020 17:00 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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On vehicles with dual exhaust, a dollar bill is held between a thumb and
forefinger on one narrow end of the bill, then dangled in the exhaust
stream, comparing one side to the other. Not particularly of much value on
single exhaust vehicles. Very subjective to interpretation as well. If you
did have a collapsed muffler, the thought would be that the bill would move
much less on that side. For what that is worth, I guess. If the crossover
passage in the heads and intake manifold, it might be more definitive. I
have never used it. Other folks may have different results.
Jim Hupy
Salem, Oregon
On Fri, Dec 18, 2020, 2:46 PM 78gmcroyale via Gmclist <
gmclist@list.gmcnet.org> wrote:
> What is THE DOLLAR BILL TEST?Sent from my U.S.Cellular© Smartphone
> -------- Original message --------From: Corey via Gmclist gmclist@list.gmcnet.org> Date: 12/18/20 3:37 PM (GMT-06:00) To:
> gmclist@list.gmcnet.org Cc: Corey Subject: Re:
> [GMCnet] Dollar-bill Test This is a super old thread but I thought I'd
> update for anyone reading here... after getting my timing right, and
> replacing both mufflers andresonator, this reversion has stopped. It no
> longer fails the "dollar bill test". Not sure what it was that fixed it but
> I'm not complaining-- Corey P / Hilliard, OH / 1974 Glacier 26' / 3.70 FD /
> ION Wheels_______________________________________________GMCnet mailing
> listUnsubscribe or Change List Options:
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| Re: [GMCnet] Dollar-bill Test [message #360975 is a reply to message #360944] |
Sat, 19 December 2020 10:43 |
sgltrac
Messages: 2797
Registered: April 2011
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There is another "dollar bill test" as well as the trucker C note. We used
to use a dollar bill to check the fitment of doors and trunks. Close the
door or trunk with the bill trapped between in the joint at the seal. Pull
the bill out and note the amount of drag. repeat at several areas of that
panel to verify a good seal.
Trucker C note. When driving at night to not fall asleep hold a $100 bill
out the drivers window pinched between index finger and thumb. Thought is
you won't fall asleep cause you will let go of the bill.
Sully
Bellevue wa
On Fri, Dec 18, 2020 at 3:19 PM 78gmcroyale via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Thank Jim. I've never heard about it.Sent from my U.S.Cellular©
> Smartphone
> -------- Original message --------From: James Hupy via Gmclist gmclist@list.gmcnet.org> Date: 12/18/20 5:01 PM (GMT-06:00) To:
> gmclist@list.gmcnet.org Cc: James Hupy Subject:
> Re: [GMCnet] Dollar-bill Test On vehicles with dual exhaust, a dollar bill
> is held between a thumb andforefinger on one narrow end of the bill, then
> dangled in the exhauststream, comparing one side to the other. Not
> particularly of much value onsingle exhaust vehicles. Very subjective to
> interpretation as well. If youdid have a collapsed muffler, the thought
> would be that the bill would movemuch less on that side. For what that is
> worth, I guess. If the crossoverpassage in the heads and intake manifold,
> it might be more definitive. Ihave never used it. Other folks may have
> different results.Jim HupySalem, OregonOn Fri, Dec 18, 2020, 2:46 PM
> 78gmcroyale via Gmclist wrote:> What is THE
> DOLLAR BILL TEST?Sent from my U.S.Cellular© Smartphone> -------- Original
> message --------From: Corey via Gmclist gmclist@list.gmcnet.org> Date:
> 12/18/20 3:37 PM (GMT-06:00) To:> gmclist@list.gmcnet.org Cc: Corey ctpangborn@gmail.com> Subject: Re:> [GMCnet] Dollar-bill Test This is a
> super old thread but I thought I'd> update for anyone reading here... after
> getting my timing right, and> replacing both mufflers andresonator, this
> reversion has stopped. It no> longer fails the "dollar bill test". Not sure
> what it was that fixed it but> I'm not complaining-- Corey P / Hilliard, OH
> / 1974 Glacier 26' / 3.70 FD /> ION
> Wheels_______________________________________________GMCnet mailing>
> listUnsubscribe or Change List Options:>
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org>
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> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org>_______________________________________________GMCnet
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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