Home » Public Forums » GMCnet » Q. for Larry W. (Big Freeze!!)
| Q. for Larry W. [message #119908] |
Fri, 25 March 2011 10:01  |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
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Larry,,,,is your gas hot yet???Any problems with your hot gas???Did you make it home ok and any problems with the "big freeze"??? Just wondering,,,,,PL
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| Re: Q. for Larry W. [message #119954 is a reply to message #119908] |
Fri, 25 March 2011 20:18  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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| g.winger wrote on Fri, 25 March 2011 10:01 |
Larry,,,,is your gas hot yet???Any problems with your hot gas???Did you make it home ok and any problems with the "big freeze"??? Just wondering,,,,,PL
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Paul,
Actually, we are at Grand Isle LA. Just got here. We got one bad tank of gas a while back. After I filled with gas, I had lots of trouble with vapor lock. I shot the tank with a touchless thermometer and found temp at nearly 80*....that's on a 80* day with a fresh tank of gas. The gas that came from that "Loves" station must have been hot when I got it. Strange!!! After letting it sit over night, with night temps in the 40's, problem went away. As for the big freeze, while at Sierra Vista there were temps in the single digits several nights...froze and broke open the hot water tank, house water pump and two fittings in the shower. Took me several days to fix it all. Thanks to Steve and Nancy F for putting up with use while we did that. Other than that, we've put on over 5K miles since we left Menomonie with almost no troubles with the coach.
Next we head to Fontianebleu for a couple of days then on to Patterson for the rally.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Q. for Larry W. [message #120003 is a reply to message #119908] |
Sat, 26 March 2011 10:53 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
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I'm runnun 73's right now but plan on 74's. Still have a problem when running at hiway speeds and the secondrys open it goes very lean/pings then goes back to where it should be. Thats with the hangger very high and the smallest/richest rods installed.(on the secondarys) This doesn't happpen if I punch it from about 30 mph. Very odd. Did a bunch of testing with the cover off on the service road of I-70. Steep hills too so I gave it quite a work out and never had that problem. Those secondarys pop open instantly,,,,,so,,,,I'm thinking I might tighten the spring a little OR use a restriction in the vac line going to the pulloff.Not sure. Posted this problem twice on Cliff Ruggles quadrajet forum but no help. I would think 509ci at 3000rpm would open the secondarys instantly comapared to a 350/400/403!!! Don't have my notes in front of me right now, so I don't remember the rods/hanger sizes,,,,,,,,PL
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| Re: [GMCnet] Q. for Larry W. [message #120012 is a reply to message #120003] |
Sat, 26 March 2011 11:23 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Paul, have you considered that your ping at light throttle may not be carb
related but vacuum related. At highway speeds with good vacuum present on
the advance cannister you will have more advanced timing than you do when
you mash the throttle at low rpm. More advance, more ping. I don't know what
setup you have on the ignition, but I would sure look there as well as into
the Qjet. Just what I would do. I seem to recall that your Cad 500 runs
quite warm, like 205. Elevated cylinder temps promote rapid flame front
spread, with the same result, pinging. How high is the compression ratio?
Some of these RV type camshafts promote cylinder filling at lower rpms and
that can also lead to knocking and pinging at lower throttle openings. I am
not critisizing, just trying to expand on the possibilities for your
pinging. What I have found through the "cut & try" process is, less advance
will help control ping as well as rich mixtures. Also, are you running an
EGR valve. If that sticks closed and no exhaust gasses get mixed into the
incoming fuel/air, same result, more ping. When you get one of these engines
to produce good horsepower and you load them quite heavily as is the case in
the GMC, these problems often arise when they wouldn't in a much lighter
automobile application. I try to change one thing at a time & then measure
the results. When you change combinations of things at once it is hard to
determine what helped and what didn't.
Jim Hupy
Salem, Or
78 GMC Royale 403
On Sat, Mar 26, 2011 at 8:53 AM, Paul Leavitt <leavittpaul@yahoo.com> wrote:
>
>
> I'm runnun 73's right now but plan on 74's. Still have a problem when
> running at hiway speeds and the secondrys open it goes very lean/pings then
> goes back to where it should be. Thats with the hangger very high and the
> smallest/richest rods installed.(on the secondarys) This doesn't happpen if
> I punch it from about 30 mph. Very odd. Did a bunch of testing with the
> cover off on the service road of I-70. Steep hills too so I gave it quite a
> work out and never had that problem. Those secondarys pop open
> instantly,,,,,so,,,,I'm thinking I might tighten the spring a little OR use
> a restriction in the vac line going to the pulloff.Not sure. Posted this
> problem twice on Cliff Ruggles quadrajet forum but no help. I would think
> 509ci at 3000rpm would open the secondarys instantly comapared to a
> 350/400/403!!! Don't have my notes in front of me right now, so I don't
> remember the rods/hanger sizes,,,,,,,,PL
> _______________________________________________
> GMCnet mailing list
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| Re: [GMCnet] Q. for Larry W. [message #120028 is a reply to message #119988] |
Sat, 26 March 2011 14:45 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Larry,
Isn't the Q-Jet on your Caddy a special altitude compensating model?
Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Larry
Sent: Sunday, March 27, 2011 1:20 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Q. for Larry W.
Ahhh...now I know what you are getting at....Still using the Q-jet. Found
myself running a little lean at lower elevations, so changed from .072's to
.073's. Runnign pretty good now. Averaging 15.4 O2 or so on the flat at
60mph. Hope to do the EFI this summer with another fella that is running a
500.
How's things?
--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Q. for Larry W. [message #120033 is a reply to message #120003] |
Sat, 26 March 2011 16:04 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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| g.winger wrote on Sat, 26 March 2011 10:53 |
I'm runnun 73's right now but plan on 74's. Still have a problem when running at hiway speeds and the secondrys open it goes very lean/pings then goes back to where it should be. Thats with the hangger very high and the smallest/richest rods installed.(on the secondarys) This doesn't happpen if I punch it from about 30 mph. Very odd. Did a bunch of testing with the cover off on the service road of I-70. Steep hills too so I gave it quite a work out and never had that problem. Those secondarys pop open instantly,,,,,so,,,,I'm thinking I might tighten the spring a little OR use a restriction in the vac line going to the pulloff.Not sure. Posted this problem twice on Cliff Ruggles quadrajet forum but no help. I would think 509ci at 3000rpm would open the secondarys instantly comapared to a 350/400/403!!! Don't have my notes in front of me right now, so I don't remember the rods/hanger sizes,,,,,,,,PL
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Paul,
Have you checked the time required for the vacuum pull off to cycle?
And, if you introduce more delay to improve the cruise speed secondary opening might it adversely affect the slower speed operation?
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Q. for Larry W. [message #120034 is a reply to message #120028] |
Sat, 26 March 2011 16:08 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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| Robert Mueller wrote on Sat, 26 March 2011 14:45 |
Larry,
Isn't the Q-Jet on your Caddy a special altitude compensating model?
Regards,
Rob M.
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Rob,
No, not any more. That Altitude Comp has an extra rod, hanger and jet in it. It was hard enough dealing with primary rods and jets, and secondary rods and hangers without adding in another variable. After playing with it fro several months, I finally gave in to it figuring it was to much for my pea brain to handle it, and got a early 80's Q-jet off of a 454. It has an adjustable power piston that is much easier to handle.
Just how this brain works lately....sluggish....
Larry
78 Royale w/500 Caddy
Menomonie, WI.
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| Re: Q. for Larry W. [message #120043 is a reply to message #119908] |
Sat, 26 March 2011 17:22 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Jim,,,thank you for your response. I don't believe its ignition related because I have a Autometer AFR gauge at it sweeps up to 17-1 ratio and pings and then dives down to 12/13-1 at wot. Yes it runs hot. In the trip in Sept to Ohio and Dqu. it ran as high as 220+ with the ac on. But on the really cold trip to Tx in December(in search of warm bike riding weather,,,HAAAA) with temps as low as 27 its right at the 190-195 temp of the thermostat. Dick P. rebuilt and converted my 72 Caddy dist. to pertronix. He sent me a card with it but I think its carb related,,,,thanks again,,,,PL
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| Re: [GMCnet] Q. for Larry W. [message #120081 is a reply to message #120034] |
Sat, 26 March 2011 21:55 |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
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Senior Member |
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Larry,
Glad to hear I'm not the only one to give up on the altitude
compensator, just too many variables on the darn thing.
I went to a 76 Cad carb, which works well if I could quit
twiddling with the APT adjustment. LOL
Gary Kosier
>
> Rob,
> No, not any more. That Altitude Comp has an extra rod, hanger
> and jet in it. It was hard enough dealing with primary rods
> and jets, and secondary rods and hangers without adding in
> another variable. After playing with it fro several months, I
> finally gave in to it figuring it was to much for my pea brain
> to handle it, and got a early 80's Q-jet off of a 454. It has
> an adjustable power piston that is much easier to handle.
> Just how this brain works lately....sluggish....
> --
> Larry :)
> 78 Royale w/500 Caddy
> Menomonie, WI.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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