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#1 |
Registered User
Join Date: Jan 2013
Location: Las Vegas,NV
Posts: 59
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I have a 1968 C10 Stepside w/ a 350 crate engine that has 15000 miles and gear vendor overdrive. I just put a new Holley manual choke 2 barrel carb on it. Yesterday I was on the interstate and when I got up to 65mph it would hold but then start to jerk and go down to 55mph then to 50mph. It runs fine when I am on surface streets and going only up to 45mph but once I go to 60mph it starts to do it again. Today, I'm going to change the spark plugs.
Anyone Have any ideas or have experienced this same problem. -Jon Cheun |
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#2 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Re: 68 won't go passed 60mph
Is the choke open?
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#3 |
Active Member
![]() Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: 68 won't go passed 60mph
Ignition could be the culprit or it may be fuel related. Weak fuel pump, restricted fuel lines, filter clogged up, or float problem -fuel logged or has hole depending on what kind you have.
Other possibilities are distributor or may timing. Hard to say until you start eliminating the possiblities.
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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#4 |
Active Member
![]() Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: 68 won't go passed 60mph
Forgot to say welcome...
Also, don't know if you're aware of it but have a double post. You may want to delete the other one.
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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#5 |
Registered User
Join Date: May 2010
Location: Hillsboro, Oregon 97123
Posts: 1,300
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Re: 68 won't go passed 60mph
This might sound silly but is the fuel filter Inside the Carb in backwards...sound like its loosing flow...
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Measure with a yard stick Mark with Chalk Cut with a torch ![]() Built it yourself, don't count on others to to do it for you or with you. It will never get done |
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#6 |
Registered User
Join Date: Apr 2010
Location: Buford, Ga
Posts: 205
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Re: 68 won't go passed 60mph
yeah, I was thinking the same sort of thing.. I had that issue with a wrong fuel filter in the carb, when it was tightened in, it crushed the filter restricting the fuel flow.
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In my opinion, it works best to have the seat out so you have room to flop your body around while standing on your head. -ashx2 |
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#7 |
Registered User
Join Date: Jan 2013
Location: Las Vegas,NV
Posts: 59
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Re: 68 won't go passed 60mph
Thank You Everyone for your suggestions.
My fuel pressure gauge read only 1 psi when it should be around 5-7psi. I had a clogged fuel filter so I replaced it. Thank You for the welcome. Sorry if there is a double post. I am still learning how to use this forum. Here is a photo of my 68 Last edited by JonCheun; 01-05-2013 at 08:50 PM. Reason: add a photo |
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#8 |
Registered User
Join Date: Jan 2009
Location: pleasant grove, UT
Posts: 399
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Re: 68 won't go passed 60mph
NICE stepside love the paint
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#9 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,621
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Re: 68 won't go passed 60mph
Nice truck! Glad you found the problem. And welcome to the site!
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#10 |
Registered User
Join Date: Feb 2011
Location: North Carolina
Posts: 993
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Re: 68 won't go passed 60mph
Sweet truck glad ya got it fixed!
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#11 |
Registered User
Join Date: Mar 2006
Location: Pittsburgh
Posts: 1,694
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Re: 68 won't go passed 60mph
Nice truck
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Nate 1967 short fleet Project Blue Goose 'If it don't bounce back... heeheehee you go hungry!" Blues Brothers |
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