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11-23-2014, 01:11 AM
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#1 |
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Registered User
Join Date: Mar 2013
Location: salt lake city utah
Posts: 59
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Fuel or spark or????
So it's been forever but I finally got my truck running today. Got The distributor dropped it at tdc and it started right up! Ideling just fine and throttle responded all the way through without any dead spots or stumbling. So I took it out for a drive. As I pulled out into the road I noticed right away that the truck was stumbling kinda jumping and as I past about 1/4 throttle it cleaned up fine but then as I shifted from 2nd to 3rd it did the same thing, and did the same thing going into 4th. So In each gear after I get past about 1/4 throttle it's fine. I'm not the greatest gear head so I figured I'd ask you guys. Can't really think what it could be. Any help would be great.
Truck: 1971 Chevy c20 Motor: newly built 307 Trans: 4 speed manual (newclutch/flywheel) Carb: edlebrock 650cfm 4 berrel Intake: edlebrock high rise Distributor: hei |
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11-23-2014, 01:32 AM
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#2 |
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Registered User
Join Date: Jan 2011
Location: Redmond, OR
Posts: 756
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Re: Fuel or spark or????
General rule is whichever you think it is , it will be the other. Lots of variables. Double check your firing order, no moisture in the cap, no shorting plug wires (this was my nemesis), tight distributor hold down bolt, clean fuel filter, carb floats set correctly, etc.
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68 Chev C20- son has it now 83 K20 - bought from son 70 C20 - in progress |
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11-23-2014, 07:47 AM
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#3 |
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Registered User
Join Date: Dec 2013
Location: DALLAS, TX
Posts: 268
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Re: Fuel or spark or????
If the carb has a filter in it. I would start there. Mine was doing the same thing.
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11-23-2014, 08:13 AM
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#4 |
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Special Order
  
Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,861
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Re: Fuel or spark or????
Fuel, spark, or.... air! That's it. Well, now fuel has to be questioned on whether it has morphed into crap you would never willfully pour into your truck. So there's the question. You said,"after a long time...", so how fresh is the fuel? If a truck runs it's getting fuel. If it stumbles or even stalls under load, hard throttle, hills, etc., then runs fine when you let off, there's a good chance the filter r something else is restricting it. Yours is stumbling at the bottom end so I suspect impotent dirty funky so-called fuel*...w/o knowing more facts.
* Yes, I hate ethanol
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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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11-23-2014, 09:17 AM
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#5 |
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Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: Fuel or spark or????
what type of distributor an hei ? do you have it hooked up properly with the 12volts required ?? points ?? are they setup ??
bad gas and clogged filters cause problem too
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71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY |
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11-23-2014, 01:23 PM
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#6 |
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Registered User
Join Date: Mar 2013
Location: salt lake city utah
Posts: 59
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Re: Fuel or spark or????
Well, I drained the tank, put new 91 oct fuel in with a fuel additive and a brand new inline filter. I'm pulling my hair out. Hahaha
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11-23-2014, 01:29 PM
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#7 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,547
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Re: Fuel or spark or????
What's your initial timing set at?
Exactly which intake? How long did you warm it up before driving it? Stock exhaust or headers? Heat riser working or eliminated? Stock air cleaner? And don't worry about hair loss! That's why they invented toques!! LOL!! |
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11-23-2014, 01:59 PM
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#8 |
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Registered User
Join Date: Mar 2013
Location: salt lake city utah
Posts: 59
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Re: Fuel or spark or????
Messed with the timing a bit to where the problem seems to be not as apparent I'll have to check. The intake is just an old edelbrock performer. I let it idle to where the thermostat opened. Eliminated heat riser. Stock filter. Headers with 40 series mufflers.
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11-23-2014, 02:23 PM
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#9 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,547
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Re: Fuel or spark or????
More timing helps at your elevation. Don't be afraid to go up to 16 or 18 initial.
With no heat riser it's just cold intake plenum. Fuel puddles and it lean missfires till the plenum warms up completely. |
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11-24-2014, 12:05 PM
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#10 |
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Registered User
Join Date: Oct 2011
Location: salem oregon
Posts: 101
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Re: Fuel or spark or????
any vacuum leaks? iirc a vacuum leak will cause power delays until the rpms catch up. vacuum is essential for proper throttle response. any leaks are going to suck in air instead of fuel/air from the carb.
also make sure your + 12v wire to the coil/hei is dedicated. had a similar problem with mine. the electric choke ran on the same wire and it wasn't charging the coil completely. I only noticed the power drop when I was driving. it ran fine in park.
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 USMC SEMPER FI 68 Chevy Longhorn 350/400 factory posi |
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11-24-2014, 03:34 PM
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#11 | |
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Registered User
Join Date: Jun 2014
Location: Glendale, Arizna
Posts: 1,642
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Re: Fuel or spark or????
Quote:
Is the distributor old, or new? Did you check the rotor shaft, maybe it's sticking and delayed advance? After verification that the rotor shaft is moving right (mechanical flyweights) advance timing till it either cranks slow or pings, then back it off where it don't. Record where it falls and back it off another 2' to account for future warm weather. |
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