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#1 |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: heard this one yet????
yes sir, thank you. i've sprayed and used the propane technique and can't seem to find any change in rpm's. i noticed my accelerator pump is not "squirting" like its supposed to. i will prolly try that tomorrow.
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#2 |
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Join Date: Feb 2012
Location: So. Cali.
Posts: 2,673
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I'm subscribed as I'm keen to hear the final solution .
I've had a few inline 6's that had vacuum leaks between the intake manifold and cylinder head but only from below ~ this meant burning my hands when I was testing for vacuum leaks with the engine running . ? Have you yet attached a vacuum gauge (cheap at pawn shops etc.) to the direct manifold vacuum ? . maybe tweak the rubber hose bits at both ends of the PCV line ? . With 10 degrees initial advance (must be zero vacuum to the dizzy @ idle !) you should be getting 21" of vacuum steady as a rock if not more at hot idle .
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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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#3 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,946
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Re: heard this one yet????
I would try spraying something inert from underneath that could enter the alleged leak. Maybe nitrogen?
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#4 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: heard this one yet????
Quote:
yes sir, that is one spot i did not try (under the intake). that's first on my list tomorrow.....
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#5 |
Registered User
Join Date: Nov 2017
Location: Mound City Missouri
Posts: 24
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Re: heard this one yet????
Does this still have points ? If not are still running the ballast resistor ? Have seen HEI and other systems that eliminate the point system with a ballast resistor still in the line , they don’t run well that way . It takes 12 volts to make them work .With that air cleaner you have on it’s probably a normal carb sound you are hearing. I don’t think its a vacuume leak, or you should of found it by now.
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Mark, 1969 custom camper, 454,th400,373posi |
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#6 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: heard this one yet????
Quote:
no sir, i have the petronix ignition. no more points or resistor. ok, i couldn't remember if i would hear that "sucking" noise when i drove it 20 years ago. if thats the case, ill live with it......the one thing that is bugging me is the sputtering at a quarter throttle in all 3 gears. can't really cruise through town in any gear when it bucks and jerks with just a little pedal ![]() ![]() thank you all for your help!!!! sorry to be a pest!!!!
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" Last edited by stevenfromtexas; 08-02-2018 at 10:38 PM. |
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#7 |
Registered User
Join Date: Nov 2017
Location: Mound City Missouri
Posts: 24
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Re: heard this one yet????
17 pounds of vac is good , is there a ballast resistor on the firewall ?
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Mark, 1969 custom camper, 454,th400,373posi |
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#8 |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: heard this one yet????
maybe we could all meet in a central location and discuss all of the issues we have with our pickups.......
wait...isnt that called a "car show".......
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#9 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: Stumble / Stalling
Quote:
thank you all for your suggestions!!!
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#10 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: Stumble / Stalling
Quote:
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#11 |
Registered User
Join Date: Feb 2012
Location: So. Cali.
Posts: 2,673
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Re: heard this one yet????
Yes, that's the float bowl valve and is separate from the accelerator pump .
Sometimes the lip of the accel. pump plunger rubber gets caught during installation and flips up, reducing the ability to pump much fuel .
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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: Jun 2015
Location: @
Posts: 890
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Re: heard this one yet????
only getting 17 inches of vacume did you try to adjust the distributor or just the carb ? sometimes the distributor will give you a few more inches of vacume and adjusting the distributor with the vacume guage will help you find your motors happy place timing wise . tons of videos on you tube that can explain way better than I can type
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#13 |
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Join Date: Feb 2012
Location: So. Cali.
Posts: 2,673
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Yes, this is possible, they taught it @ the GM factory training I took close to 50 years ago :
Warm up the engine fully then set the idle to about 700RPM . connect the vacuum gauge to the direct manifold vacuum port and watch it closely as you s l o w l y advance the distributor ~ as you advance the timing the gauge's needle will rise, eventually it will begin to twitch, stop and ease it back until you get the highest steady vacuum, snug down the dizzy's clamp and take it for a test drive, radio off, windows closed ~ when you get it to 35 ~ 40 MPH in top gear on a flat and level road, depress the foot feed to the floor and listen for knock or ping noises ~ if none, you're good to go . If you hear even a -slight- ping or knock, stop and using the timing light, back the timing off -ONE- degree, snug the dizzy and try it again . The idea is to give the engine all the advance it'll take without any ping . This is called the "Throttle Ping Test" and is how old GM i6 engines were properly tuned before the $tealerships decided that test drives were a waste of time . actually they just wanted us to work harder and faster, no matter if the Customer didn't get the high quality works they'd payed for . Give this a try, you'll prolly like the result . I hope you knew to open the spark plug gaps to at least .040" after in stalling the Pertronix Ignitor ? .
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-Nate Geezer '49 3100 235 W/ Muncie SM420 SOLD '69 C/10 shortbed sidemount survivor 250 L6 W/ 350TH ![]() Last edited by VWNate1; 08-03-2018 at 09:35 PM. |
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#14 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: Vacuum Ignition Timing
Quote:
thank you for this. i've put over 100 miles driving it around a 5 mile loop after doing the little tweaks seeing what works and what doesn't...... yes sir, i actually have them a little more than that. i read some older post that mentioned even more than that of a gap. mine are at .055 right now. you reckon i should move the down to .040?
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#15 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: heard this one yet????
Quote:
i redid the vacuum test this morning. i was taking the reading from the carburetor port. i re-read these post and i guess i missed the "manifold" port for vacuum test. I have a steady 20''of vacuum there. i'll do all of your test again in the morning. assuming 20'' of vacuum is the correct amount, or do i go as high as possible???
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#16 |
Registered User
Join Date: Nov 2017
Location: Mound City Missouri
Posts: 24
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Re: heard this one yet????
Fantastic glad you stayed with it , no doubt a new educational situation. Head scratchers like these can be such a challenge for the best of mechanics and are easy to give up on.
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Mark, 1969 custom camper, 454,th400,373posi |
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#17 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: heard this one yet????
Quote:
"educational situation" for sure!!!! the whole project has been. this has been a BLAST!!!
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#18 |
Registered User
Join Date: Feb 2012
Location: So. Cali.
Posts: 2,673
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Don't you just love the satisfaction of taking the time to work through a problem your own self ?
![]() This is why I always push folks to try the DIY, you'll usually do a better job because YOU CARE and won't rush the job . Now, figure out why it needs so much idle screw to keep it running and eventually you'll get to zero vacuum @ idle . Peppy little thing, ain't it ? ![]() Unless you have problems with missing or stumbling, leave the spark plug gaps where they are ~ the ideal thing is : as much gap as they'll take without causing running issues . We can help you get a better coil *if* you want, what the Pertronix does is : drives the stock coil to it's maximum output all the time ~ points don't really do a good job of switching the current on and off .
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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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#19 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: ! Progress !
Quote:
this was Dads pickup and the one i learned to drive a standard in, so i will have it forever, and do small tweaks here-and-there but i do have the fever to do another one. took my daughter ( 9 ) to the tennis court today to hit-a-round.....good friggin' feeling!!!!!
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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#20 |
Registered User
Join Date: Feb 2012
Location: So. Cali.
Posts: 2,673
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Very nice indeed .
I hope your Daughter likes the rig and decides to keep it . I was worried there'd be some Hot Rodders who don't understand how ported vacuum works, some really big heavy duty V8's use manifold vacuum, it's very strange . The collective knowledge here is amazing .
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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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#21 |
Registered User
Join Date: Feb 2012
Location: So. Cali.
Posts: 2,673
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"question....
the "C" shaped linkage at the bottom of the carburetor, connecting the accelerator pump to the throttle body, can that be adjusted/tweaked/bent slightly to help with anything I've got going? " . Yes, that is why it's 'C' shaped . There's quite a lot of good info on these old Rochester 'B' series carbys in the factory shop manual, it's still available brandy new for about $30, used ones with dog eared and greasy pages for far less, you really should buy one GM also printed a nifty 194/230/250/292 engine manual......
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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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#22 | |
Registered User
Join Date: Mar 2013
Location: Hewitt, Texas
Posts: 444
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Re: Oops ~ I Missed This Question
Quote:
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Steven '67 SWB, 250ci, 3OTT.......this is my first build...... I wonder if my grand kids will say, "I would give anything to have my grand dads 2005 Chevrolet Z71" |
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