73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Eastonfrench on August 31, 2015, 01:39:28 pm
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So I pulled a 1980 K10 (350 V8) out of a farmer's barn and have brought it back to life. Ever since I started driving it, I've noticed it has really poor acceleration. My dad, who grew up driving the same truck, assures me that it isn't near as powerful as it should be.
From a stop, as well as from when rolling, if i punch the gas, it behaves as if i am slowly pressing the accelerator, and sometimes even stalls out for a second. it eventually gets up to speed, but doesn't really throw you back in your seat.
Ive replaced the following in an attempt to eliminate possible culprits:
Cap/rotor/plugs/wires
Fuel Pump
Accelerator pump
Carburetor rebuild
Air Filter
I ensured the secondary air flaps are opening as well, and I am now out of ideas. What else should i check?
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U could do a compression test and wat kind of trans do u have
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Did you replace the fuel filter? Check the ignition timing and make sure the mechanical and vacuum advance mechanisms are working correctly. How many miles on the engine? A 35 year old truck could have a lot of wear. Engine compression and timing chain should be checked along with the condition of the harmonic balancer. Tire diameter and gearing will also play a roll.
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Thanks for the replies!
It's an automatic tranny
I set the timing to factory specs. The vacuum advanced seems to be working (when I open the throttle the timing mark advances).
I did change the fuel filter, to no avail.
I haven't done any compression testing, but the truck only has 80000 original miles, and they were mostly to town and back at about 35 MPH. (An old farmer owned it).
I'm not sure how to check the harmonic balancer (or even what it is). Or a better way to check the mechanical advance?
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I would at least try it on direct manifold vacuum, without all the extra crap in the way. That's all pollution nonsense. How much of the pollution nonsense is built into the ECM is another question.
Going to manifold vacuum, you should lean out the idle, and advance the base timing from factory specs.
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I'd like to throw my $.02 in and suggest the catalytic converter may be plugged
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Zeig,
Is there any way of checking the Cat? This may be irrelevant, but theres plenty of exhaust gas coming out of the tailpipe. COuld the Cat still be plugged? Any Suggestions?
I am going to take a look at the Mechanical advanced as well as the Cat when i get off work this afternoon-Updates to come
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Not sure, I just take them off temporarily and try it. When clogged or nearing being clogged they get really hot... When sitting there at idle, does it rev good? Also do you have a stock air cleaner? Is it a quality air filter or some bargain brand. I've seen cheapo's manufactured with the filter element in backwards. They look clean but are clogged. If you have a stock air cleaner, take the filter out for a quick test. If the catalytic converter is fine and it isn't the air filter more than likely it sounds like timing. A sloppy (worn) timing chain would also cause this issue.
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...The vacuum advanced seems to be working (when I open the throttle the timing mark advances).
...I'm not sure how to check the harmonic balancer (or even what it is)
...[Is there] a better way to check the mechanical advance?
Mechanical advance is tied directly to engine RPM. Remove the vacuum hose from the distributor vacuum advance. Being very careful to avoid the fan and belts, throttle the engine while watching the timing mark with a light. The timing mark should transition smoothly with RPM change, both up and down, beginning about 1,200 RPM. Then with the engine running at 1,500 - 2,000 RPM, reconnect the vacuum hose to the distributor vacuum advance - the timing should increase.
The harmonic balancer is the cast iron hub on the front of the crankshaft that bears the timing mark. The outer ring of the balancer is vulcanized to the hub through an elastomer band. With age and use, the outer ring can gradually rotate around the hub throwing off the timing mark. For examples of how to check the harmonic balancer and the timing chain, read through Re: Not 100% what's wrong here (http://forum.73-87chevytrucks.com/smforum/index.php?topic=26872.msg223842#msg223842) and Re: 86 C10 Loping (http://forum.73-87chevytrucks.com/smforum/index.php?topic=27593.msg229607#msg229607).
To check for a plugged exhaust (cat, muffler or collapsed pipe), temporarily separate the exhaust ahead of the cat and road check for a seat-of-the-pants improvement. Alternatively, if the engine has a smog pump or O2 sensor, an AIR injection check valve or the O2 sensor can be temporarily removed from the exhaust and a 15 - 20 PSI pressure gauge plumbed into the resulting hole to measure exhaust backpressure with the engine running, which should not climb above ~1.5 PSI at 3,000 RPM. You could accomplish the same thing by drilling a small hole in the headpipe and plumbing a gauge there; then plug the hole with a screw when done. A less direct method (more interpretive) is to use a vacuum gauge on the engine while accelerating under load.
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Wow. Thanks for the input guys.
So after work, I popped the distributor cap off. The mechanical advance is spotless (theres definitely no crud keeping it from engaging).
I do have the factor breather on, with a new air filter, but I will try taking it down the block without a filter here real quick
I am going to see how hard its going to be to pop the Cat off, and give it a road test.
I am really hoping it isnt the timing chain. I cant imagine thats an easy replacement.
Thanks again...Ill be sure to post when I try some of these things.
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SO.
I went and took it around the block with the air filter off. No change, so I think it is safe to say it is getting enough air.
when I got home, I checked the Cat, and what do you know? it was STEAMIN hot. Much hotter than it should have been after a two minute drive.
So I cut it off. The whole exhaust from the cat back. Now she sounds awful ( I knew this would be the case, but it needed a new exhaust anyways), and still behaves odd. It did seem to pick up a little horsepower, but from low rpms if you stomp on it, it stalled out for a second or two still.
So the issue is certainly not exhaust, and certainly not air. Where should we go from here fellas?
Thanks again. I really appreciate the help trying to restore this thing.
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Check compression, I almost can guarantee it is low, by stuck rings from sitting, two ways to fix, keep running or do a re-ring job
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Update:
I bought a piece of exhaust union and hooked the muffler back up (its just 2 foot shorter of an exhaust system). Once i hooked it up, I think the truck is a LOT better. It must like a little backpressure. I will let yall know more after i take it on a long drive tomorrow. Cheers.
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Hey guys. I've got a 1980 k-10 with a 350 and a quadrajet. I've got an acceleration problem. When you start the truck up, and drive away, all is fine. But if I give it any more than half throttle, it falls on its face. Sounds like it dies but if I let off the gas it fires back up. I can ease into the gas and it will take full throttle, but I have to really baby it.
I've noticed that if I drive 15 miles, it tends to be less extrem (it lets me give it more throttle before stumbling). I really want to get this thing tuned in so that I can put the pedal all the way down from a stop.
I've replaced the fuel pump and filter. New plugs wires cap and rotor within the last 6 weeks. Removed the cat. Rebuilt he carb and put a new accelerator pump, needle and seat in. Timing is set on 10 degrees initial, and the vacuum and mechanical advance both appear to be working. I set the choke by feel, but it appears to be fully disengaged once it warms up in the driveway (the flap is totally vertical)
I checked for a vacuum leak a couple weeks ago by spraying carb cleaner but I didn't find anything.
Other indicators that may not be related: I get a small puff of smoke when starting it. In park, she revs up awesome, but kind of cackles out of his exhaust at high RPMs.
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IMO... too much gas or timing is off.. what fuel pressure carb running?.. I would advance timing till it pings under load then back off a little.
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LSXCHEVY:
I don't know what the fuel pressure is, how can I check that?
Also, what is "ping"? I set the timing at the degree it calls for on the sticker under the hood. When you say pings under load, what do you mean? I don't have a tach, so it's hard to set anything at designated RPMs.
I am very handy, but very inexperienced with these older trucks. I suspected the fuel pressure, which is why I put the new fuel pump on.
Another thought, could it be spark plug gap? Anyone know what gap I should run? I just set them on what autozone told me at the time. What should they be?
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Update: I ran it really hard and got her up to temperature and now it won't do it at all! Maybe that has something to do with it? What would cause these issues only until the truck is hot? I let it warm up 5 minutes before I dive it in the mornings and its 80 degrees here
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A slightly low float level can cause it, as well as choke adjustment, adjustment of the secondary air valve spring, and/or the secondary lock-out. There could also be an anemic accelerator pump shot due to a stiff rubber pump cup that bypasses fuel when it's cold.
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im going to add to what these guys said by what i just did to my truck to get it ready for the mud bog where you need all your power on the take off to get your wheels spinning and i had stumble on acceleration for the longest time.
first: floats in the carb bowls had to be adjusted to the right level
second: timing set at 15° with the vacuum advance unhooked and plugged. came out to something like 35° total
third: hooked vacuum advance up to the manifold vacuum instead of ported. (make sure you vacuum advance is working)
just by these three things i dont think my truck ever ran so good now i might need a new clutch lol
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fuel pressure is, how can I check that
I have a fuel pressure gauge on the fuel line near the carb...electric pump with regulator makes it easier. if you have a mechanical pump, its a little more involved.
Also, what is "ping"? I set the timing at the degree it calls for on the sticker under the hood. When you say pings under load, what do you mean?
someone with more experience than me can chime in but I believe that the timing should change over time cause of drivetrain parts wearing out, sticker from 1980 might not be as relevant. advance the timing until you drive it under a load and will hear slight "pinging" or like a metal can sound type at high load or high rpm
I also would try the things mention by Irish, good info.. best thing I did for my carb was buy a wideband AF meter to take all of the guess work out of it...
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ping or knock
Knock
Occurs when part of the air-fuel mixture in the combustion chamber away from the spark plug is spontaneously ignited by the pressure from a flame front originating from the spark plug. The two colliding flame fronts contribute to the “knocking” sound.
Knock occurs more frequently when using low octane fuel. Low octane fuel has a low resistance to knock (low resistance to ignition)
Knock is related to ignition timing. (Knock is sometimes referred to as “Spark-knock”.) Retarding the ignition timing will reduce knock.
Heavy knock often leads to pre-ignition.
Heavy knock can cause breakage and/or erosion of combustion chamber components.
Knock is sometimes referred to as “ping” or “detonation”.
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Did this problem just start one day or was something done that possibly caused this to happen. A little more history if possible.
First thing on my mind is fuel supply for falling on its face.
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Some more: Clogged fuel filter, or bad rubber line from the tank to the steel line, or from the steel line to the pump.
Another could be the choke set too lean. It comes off too soon, giving you a period when you are running lean until the truck warms up. Will run fine stone cold, will run fine hot, goes through a period when it is so-so.
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Hey guys. I think my truck is not getting enough fuel at WOT, and as a result stutters/bogs for a second. I've got a two dollar fuel filter in the Quadrajet fuel inlet. Has anyone ever tried removing that and maybe installing an inline filter somewhere else in the line? I know autozone sells generic performance fuel filters. just wondering if anyone has done this or knows if it could help with fuel starvation when I gun it. I have a brand new fuel pump, and have done my best to make sure lines are tight and that there's no air getting in the system.
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I always pull the filter from inside the carb and then cut the steel line and put a filter in with soft lines.
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Locate a new in-line fuel filter in a convenient and easily accessible spot between the fuel pump and the carburetor, so the filter is always pressurized by the pump.
If the engine bogs just for a second at WOT, it sounds more like an issue with a lean accelerator pump shot, secondary air valve adjustment, power circuit timing, or vacuum advance issue. Actual fuel starvation resulting from poor fuel delivery up to the carburetor, or an excessively low float setting, generally will manifest more as an overall loss of engine power with increasing throttle demand.
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enaberif- So you just cut the hard line, and hose clamp soft line section in, with a fuel filter?
bd- I also think I have a generally low amount of HP. I've adjusted the secondary air valves, put a new accelerator pump in (though if there is a way to adjust it, I have no idea how). And I have verified that the timing and advanced mechanisms are in order.
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enaberif- So you just cut the hard line, and hose clamp soft line section in, with a fuel filter?
bd- I also think I have a generally low amount of HP. I've adjusted the secondary air valves, put a new accelerator pump in (though if there is a way to adjust it, I have no idea how). And I have verified that the timing and advanced mechanisms are in order.
Yup! I tucked it down near the frame rail out of the way of anything dangerous. In the new year I'll be redoing the hardline from the carb to the pump so there is less soft line than I have now.
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May i also ask, i have the standard carb filter AND an in-line. Is that ok? Should i only have one?
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There's nothing wrong with that, but you are not really gaining anything. Just don't forget to replace the filter in the carb, occasionally - lol. Or, remove it completely and rely on the in-line filter.
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I guess when i'm bored i'll change it out. I mean ditch the cheap china inline one. It was there when i got the truck.
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Hey guys, I was fiddling with my hot air choke, and was wondering: can choke springs get old and lose some of their travel?
It seems like If i richen the choke enough for the engine to start well, the High idle never kicks off because when the spring is fully relaxed, it has not traveled far enough (though it is close) to kick down the idle. I was thinking about buying a new choke spring, ust wanted your guys' opinion.
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You are on the right track. Begin by replacing the choke t-stat. And, check the choke vacuum breaks (pull-offs) to make sure they are working and not perforated. Note that some secondary pull-offs incorporate an air bleed and won't hold vacuum for longer than a few seconds. Primary pull-offs should hold vacuum indefinitely.
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What will happen if you pull that wire off your choke, continuous high or low idle?
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What will happen if you pull that wire off your choke, continuous high or low idle?
No wire on hot air chokes.
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Make sure your stat gasket is in good shape as well as the choke tube to ensure your drawing hot air to the stat.
It's not hard to convert to electric choke from hot air choke.
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Ok, assuming it was electric...
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Hey Guys thanks for the input. The air tube is in good shape. And my puloff holds vaccum. it is a weird system with only one pulloff (ill attempt to show a picture).
I just feel like the spring needs more travel. It either starts good but never steps down, or needs gas to start, but slows down nicely!
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Pictures are worth thousands of words! Replace the choke thermostat and gasket, blow out the hot air tubes with compressed air, verify the correct float level setting, and double check the pull-off adjustment with the appropriate gauge (a drill or ruler).
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bd-
I will replace the choke stat today or tomorrow.I also am confident the float is good, I set it when I rebuilt the carb a couple months ago. How do I check the pulloff adjustment on this carb? I can't find it anywhere.
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Look forward through the 1980 Service Manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Service/ST_330_80_1980_Chevrolet_Light_Truck_Service_Manual.pdf) beginning on page 6C4-6 (pg 644). Full choke circuit adjustment is described therein.
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Got ride of the cheap china in-line fuel filter today, much better. Anyone know how often is best to change the one in the qjet?
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Drop the q-jet one and put a metal filter in made by wix. It is better, larger and provides more filtration than that q-jet one.
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You mean in place of the qjet filter, or external?
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external. the qjet ones get plugged too fast
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Ok, will look into it. How about a pic??
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Hey guys. Still chasing an acceleration issue. as long as i am easy on it, my truck runs great, however when I apply the accelerator too quickly the motor bogs down, and very rarely, it dies. It always starts right back up and my plugs arent wet or black so i dont think it is flooding. I think its the opposite: I think its getting too much air too quickly, resulting in a mixture too lean to run with much power. I have a new fuel filter, and new pump, so I find it hard to believe it isn't getting fuel enough, but I could be wrong.
How can I decrease the air to see if my hypothesis is correct? I know how to tighten the secondary air valve tension. Would that be where to start?
Am I headed in the wrong direction completely?
I've rebuilt the car. New accelerator pump. Fuel Pump. Checked the vacuum and mechanical advance. I really feel like my fuel:air ratio is too lean on acceleration.
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I had the same issue on my '87 R2500. Check your intake gasket. You may have a small leak somewhere in it. Start the truck and let it idle, take a can of starter fluid or PB blaster and spray the line separating the intake from the head. If you use starter fluid, you'll know when you find a leak because the engine will pick up, whereas if you use PB blaster your engine will bog down. I did that and found a leak and replaced my gasket and it was better after that but I still needed a fuel filter but now it runs better than ever with no bog down. Hope this helps.
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Square body- Thanks for the input! My dad tried that trick as well with no luck. But I may give it another try! The intake to motor gasket is the only one I haven't replaced so that could very well be it!
Anyone else have other things to try while I'm in there?
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Also check all of your vacuum hoses with the same method stated above for vacuum leaks
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Could be a bunch of things going on. Timing at the point of acceleration, your accelerator pump on the carb, the secondaries on a quadrajet spring doesn't have enough tension and opens too soon, ( I had that problem on my race car), or too small of jets in the carb for the engine size (been there done that)
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Do the symptoms occur both cold and operating temp?
Is the hesitation instantaneous with throttle opening, or does it begin to accelerate for a quarter second before falling on its face? Looking down the carburetor throat with a good flashlight and the engine not running, is there a good strong well defined stream of fuel with throttle opening, without any lag or dribbling? Does the accelerator pump fully return to its up position with throttle closing and closely follow (remain in constant contact with) the pump lever? Did you verify unhindered vertical movement of the primary power piston? Did you check the fuel bowl cover (air horn) for flatness with a straight edge when you had it off? What is the carburetor number and where did you set the float level?
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Rich- It could be the secondary air valve spring is too loose, I may give that a try since its an easy, reversible solution. Do you, or anyone, have a way to tell how tight is tight enough? the way I did it was to (using a dental mirror) back the spring all the way off, and then slowly turn it until the tang on the spring just barely came into contact with the catch on the air valve, so that there is basically no tension when the valve is shut, but tension is applied the second it begins to open. Is that not correct?
bd- The hesitation is instantaneous.
Fuel stream appears to be fine.
Accelerator pump is brand new, and quickly returns to its relaxed position after use.
Power piston is clean and has unhindered movement.
I did not check the air horn for straightness.
Though I don't have the carb number on me, I looked it up and can assure you the float level was set to specs.
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Do you, or anyone, have a way to tell how tight is tight enough? the way I did it was to (using a dental mirror) back the spring all the way off, and then slowly turn it until the tang on the spring just barely came into contact with the catch on the air valve, so that there is basically no tension when the valve is shut, but tension is applied the second it begins to open. Is that not correct?
You set the air valve too loose. There is a precise adjustment based on the carburetor number. Instructions should have been packaged with the kit. Post the carb number.
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I was mistaken I did not simply turn it until contact. I did that, and then turned it in, but I am not sure how much. Maybe a full turn? I dont remember. How far was I supposed to? I could't find any concrete information regarding the amount of tension I was to put on the thing
The Carbuerator is a Rochester Quadrajet the info is
17080290
2049CYH
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From the 1980 Service Manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Service/ST_330_80_1980_Chevrolet_Light_Truck_Service_Manual.pdf) Section 6C4, M4MC Model Carburetors...
QuadraJet 17080290
- Float Level = 15/32"
- Pump Adj = 9/32", inner hole
- Secondary Lockout = 0.015"
- Air Valve Spring Adj = 7/8 turn past closing
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def sounds like your secondaries are opening too soon -
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Thanks gentlemen. I will give it a try and be back with the results.
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I had a similar issue with my 85. I have a 350 with the stock quadrajet and the truck idled great, but had serious issues bogging out, shifting, basically ran like crap under load. After changing the fuel filter and the vacuum lines, with no positive results I decided to buy a new carb. Since the motor is still basically stock I decided to try a rebuilt quadrajet from National Carburetor. Price was $175 plus shipping. Took all of 30 minutes to install and holy crap it was like driving a brand new truck. I had fought that carb for 3 years and I'm just kicking myself because if I would have know that $175 could get you this much return I would have done it day one. The carb looked brand new and the customer service was excellent. Trust me, the results were amazing. So, if you like me and using it for a daily driver now, but potentially looking to upgrade later, this is the way to go. I decided that when I'm ready to turn the heat up, I will probably buy a different carb and intake, but for now I'm extremely satisfied with the performance and mileage that it provides.
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I would ensure you don't have any kinked fuel lines or rubber hoses first before you go crazy. Check by the tank and going up to the carburetor first. Make sure you are running rigid lines
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I had a similar issue with my 85. I have a 350 with the stock quadrajet and the truck idled great, but had serious issues bogging out, shifting, basically ran like crap under load. After changing the fuel filter and the vacuum lines, with no positive results I decided to buy a new carb. Since the motor is still basically stock I decided to try a rebuilt quadrajet from National Carburetor. Price was $175 plus shipping. Took all of 30 minutes to install and holy crap it was like driving a brand new truck. I had fought that carb for 3 years and I'm just kicking myself because if I would have know that $175 could get you this much return I would have done it day one. The carb looked brand new and the customer service was excellent. Trust me, the results were amazing. So, if you like me and using it for a daily driver now, but potentially looking to upgrade later, this is the way to go. I decided that when I'm ready to turn the heat up, I will probably buy a different carb and intake, but for now I'm extremely satisfied with the performance and mileage that it provides.
I also got my carb from nat'l carburetor, it was like brand new, paid like $190 and kept my old edelbrock, sold for a lot more. (Instead of sending in for a core). Superior customer service, fast delivery and packaged well.
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What is your base timing set at, what advance can are you running, and where is your vacuum advance plugged in, manifold or ported vacuum?
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What is your base timing set at, what advance can are you running, and where is your vacuum advance plugged in, manifold or ported vacuum?
timing was my biggest problem then i plugged my vacuum advance to the manifold vacuum and now my truck runs like she never did before.
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What is your base timing set at, what advance can are you running, and where is your vacuum advance plugged in, manifold or ported vacuum?
timing was my biggest problem then i plugged my vacuum advance to the manifold vacuum and now my truck runs like she never did before.
Irish, i just did the same thing, as you can see from another post i have a fast idle, kick down issue. (another timing question) And not that it may or may not have anything to do with. But i know my engine and it sure runs better since i moved it to manifold.
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when i was driving the carbed truck everyday it was plugged into ported vacuum. since rich came along and now its just a mud truck (wish i would of knew better before) it acts like a different truck now. much much much better
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Yes! I totally agree, and thanks to rich, who I think is a expert on where these hose connections should go (ported vs. manifold) back when I first got my truck I had a long thread going on that issue that rich set the tone on. Anyway, I gotta get back to that other post and update my results.
Romans 8:2
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Not an expert, just an old fart. Old enough to remember when GM and Ford, after 30 years of using manifold vacuum, switched to ported vacuum to accommodate the pollution controls, and how hard it was to tune a car to run decently after that.
My dad had a '63 Ford, and would have run it a few more years, but decided to buy a '68 Ford when the imposition of pollution controls was looming on 1/1/1968. He ordered the '68 Ford in September 1967, and specified that it had to be built by the end of the year so as not to have those changes. If it was a post-1/1/68 build, he wouldn't accept it. He came home with it on December 23, 1967. So you could get a 1968 without the changes, because they cost the mfrs extra money, and they didn't put them on until they had to. That 1968 Ford Country Squire had a Z-code 390 FE 4-barrel that was really sweet. A friend of his bought a similar car after 1/1/68, and it was a completely different animal. Sad.
Later, when those pollution-equipped cars were available used, people would change the vacuum advance, advance the base timing, and disconnect the AIR pump, to get them to run decently. Of course, they were always hooked up properly for emissions testing....
This was the car, but he didn't have a roof rack on his, because he couldn't see punching holes in a perfectly good piece of sheet metal.
(http://www.automobile-catalog.com/img/pictonorzw/ford_usa/1968-ford-19.jpg)
Then, in 1975, my dad was in the market for a new car, but by then the pollution stuff was on all the cars and on the C-10 and F-150 trucks. So my dad bought a 1975 F-250 with a 462 Lincoln engine and a rear-end ratio for pulling his big trailer. That thing would haul . When I mentioned how quick it was, he said, "So that's why my fishing gear is always all the way in the back after you drive it." "Well, I'm just trying to make it more convenient for you to get at it." :)
Yeah, he had Fords because the Chevy dealer in town was a prick and the Ford dealer was a great guy, with a great back shop. When I was growing up, though, he had a Chevy 210 wagon. Oh, and from 1940 to 1950 he had a 1936 LaSalle Series 50. Cadillac wouldn't have vacuum advance on the LaSalle until 1939.
(http://www.wmsbrg.com/cadillac/Richmond/members/Hines/36-LaSalle-Malcom-Hines-2010_1.jpg)
My own truck now is a 1978, the last year before pollution controls were extended from 6000 GVW to 8500 GVW, so the K10 had no pollution controls in 1978. So it's legal as is anywhere in the U.S.
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That car is a gem. Thanks for the update and short story rich, all makes sense to me. Well, my favorite is a 64 impala ss. Thats going to be my retirement project when i'm an "old fart". Happy new year and stay healthy!
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Hey Guys,
After digging my truck out of a barn this last summer (2015), I have FINALLY figured out why the motor wasn't running well!
When I first got her running, the old farmer that owned it, as well as my old man, both kept going on and on about how powerful the truck would be, and how much I would love it. After months of replacing parts and making adjustments, i just COULDNT get the thing to have any kind of power. She ran fine, but when you wanted to accelerate, it was pretty gradual.
I had all but given up on it (still driving it every day, albeit slowly) when my dad said "bud, pull your truck in and let's take another look.
We put the back end on rollers, put it in drive and gave it some gas, and we noticed the secondary air valves weren't opening! I had suspected this before, and already knew how to adjust them. I loosened them up, to the point they were almost falling open. We took it out on the road, and when you put the pedal to the floor, it bogged, and died.
Dad gets out (we are on a gravel road in the snow), and stands next to the fender, looking into the motor.
"Gun it. I want to see if these dang things are opening".
I held my foot on the brake and put it under load, and he confirmed they were not even budging.
We took her back to the shop.
"You're running that thing on two barrels of a four barrel carb boy," he told me.
Then we saw it. I flipped the secondary air valves open, and pushed on the accelerator. The secondary throttle valves didn't open. Not even a little bit.
Somehow, the metal arm on the accelerator bracket had bent, and was never opening the secondary throttle plates. Not only was I running on two barrels, i was running on the two small barrels!
Now the thing is a BEAST. I advanced the timing a bit, and I am having a ton of fun being heavy footed at every stop light. I hope this helps someone someday.
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Congratulations on finding and fixing your problem. This will give someone else something to look for thanks for the update