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Oil Can Mechanic
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At high speeds the 47 hesitates. Im talking 55-60 mph. At low speeds no problem. When it does do it, if I ease up on the pedal alittle it stops. As soon as I increase speed it does it again.
Rebuilt Carb. New points, condenser, cap, rotor, vac. advance.
Timing is dead on the ball. New points set to 18. Valves adjusted. SLIGHT little miss on Idle, I cant seem to get rid of.
Other then that it drives great. Im STUMPED !!!
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Technical Advisor ChatMaster - 10,000
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What you describe is typical of fuel starvation. Could be the result of a bad fuel pump. If there are any leaks (bad connections) in the line from the fuel pump to the tank. If you have a filter in the line somewhere it could be the culprit.  
RAY Chevradioman http://www.vccacolumbiariverregion.org/1925 Superior K Roadster 1928 Convertible, Sport, Cabriolet 1933 Eagle, Coupe 1941 Master Deluxe 5-Passenger Coupe 1950 Styleline Deluxe 4-Door Sedan 1950 Styleline Deluxe Convertible 2002 Pontiac, Montana, Passenger Van 2014 Impala, 4-Door Sedan, White Diamond, LTZ 2017 Silverado, Double Cab, Z71, 4X4, White, Standard Bed, LTZ If you need a shoulder to cry on, pull off to the side of the road. Death is the number 1 killer in the world.
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First thing I would check is the coordination of the throttle plate and metering rod. Also check to make sure that the metering rod and high speed jet are the correct ones for the carb, make, model and year.
If it is fuel starvation from fuel pump or fuel line it typically takes a short while at the high speed for the hesitation or pulsation to occur.
How Sweet the roar of a Chevy four!
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Thanks for the replys Ray, and chipper. The hesitation does take awhile to occur at the high speed. Will change the fuel filter, and check the lines, and clean out the pump bowl. If it still persists. I will change the pump. Will let you know what happens. Thank you both again!
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That slight miss at an idle could be a vacuum leak, I chased one and found it was the vacuum line going to the vacuum advance.. I also agree that the high speed hesitation could be fuel starvation, the float could be set to not open soon enough or shut off too soon. along with several other things.
Life's a long winding trail, love Jesus and ride a good horse!
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Is it at the same throttle detent, or at high speed while under acceleration? I had a similar if not identical problem with a 62 Imapala with a 235 and a powerglide, and it was fuel starvation, I had a slight crack in the rubber hose connection from the tank to the steel fuel line, and it was leaning things out under a real demand. Is the engine running hotter? A lean mixture is a hot mixture. I noticed it more climbing hills and SUSPENSION BRIDGES (I will never forget that!!!!)
I thought that I had a problem with the strainer in the tank, so I was blowing back the line with compressed air and heard air leaking from under the car, when I closed the cap on the tank. Even though the system was vented it could not keep up with the volume of air that was going into the tank, forcing it to find the crack in the hose
Good luck
John
John
1954 Belair Sport Coupe
1960 2 door Impala Hardtop 348/340HP 4spd
1962 2 door Impala Hardtop 409/409 4spd
1962 2 Door Biscayne Sedan 327/250 Auto
1977 Monza Mirage 305 4 Speed
1988 Celebrity Wagon
2018 GMC Sierra 2500 HD Diesel
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oops I hit the button twice, sorry
John
Last edited by John 348/340HP; 06/14/07 08:07 AM.
John
1954 Belair Sport Coupe
1960 2 door Impala Hardtop 348/340HP 4spd
1962 2 door Impala Hardtop 409/409 4spd
1962 2 Door Biscayne Sedan 327/250 Auto
1977 Monza Mirage 305 4 Speed
1988 Celebrity Wagon
2018 GMC Sierra 2500 HD Diesel
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Replaced the fuel filter, Cleaned out the pump bowl & screen.
Blew out the lines from pump to carb, and tank to pump tonight. Checked for leaks, and found none anywhere.
Took it out for a test drive, and the hesitation was still there.
When ever Im cruising at about 50-55 no problems. As soon as I try to accelerate, and it reaches about 60-65 she starts to buck.
I let off the gas to 50-55 again no problems.
Should I replace the pump?
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Tech Advisor ChatMaster - 25,000
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Try replacing the pump as a test and see what happens.  :) :grin:
The Mangy Old Mutt
"If It's Not Junk.....It's Not Treasure!"
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The pump is the most probable cause....Sounds like a text book example.
Gene Schneider
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Backyard Mechanic
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Backyard Mechanic
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I had a "48" that stalled at high revs. I had the carby rebuilt (at great expense) plus a new fuel pump; all to no avail.
Ultimately we went for a run without the air filter and the problem went away. What it was is that there is a piece of felt in the top of the filter and it had shrunk with age and the edges were no longer located. At high revs it was sucked down and blocked the air flow. Tossed it away and no more problem.
Just a thought to consider.
Terry H
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Ordered a pump from Chevs of the 40s. Hope to see it by Wed. Will post with the results. Thanks again to all who reponded.
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Every owner of any "antique" car should have a new spare fuel pump in the trunk. If for no other reason just for peace of mind when you are on the road.
Gene Schneider
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Make sure that the fuel pump has a modern diaphram. Most of the original pre-80s diaphrams will not last with the alcohol and other stuff in modern gas.
How Sweet the roar of a Chevy four!
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Just ordered another one for the Trunk!! Thanks Gene!
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I also just orderd a spare pump fpr my truck just in case. Thanks Gene and the Filling Station loves you...Oscar :love: :love:
OSCAR ALBRETSEN
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In all the thousands and thousands of miles of driving my old cars I only had to change the pump on the road once. The carburetor was dry and not getting gas.The fuel pump didn't help because there was no gas in the tank to pump. :)
I have changed more than one at home though, mostly due to oil leaks. Also I can tell when the pump is getting weak, it takes longer for the carb. to fill after the car has sat for a few weeks.
Gene Schneider
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OSCAR ALBRETSEN
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Hey Oscar,
You and the pick-up and those new plates will do just fine. AND, look great. Where's the show.... Redding??
What happened with the 53 Bel Air over the weekend???
Bill.
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Hi Bill, the show I am going to is in Durham. It's right next to Chico. About the belair. I went and drove it on Friday and it drove pretty nice. She was as stock as can be. She needed chrome work due to the KO chrome in 53. I told her I wanted it. She said she had to go to Sacramento for her grand daughters graduation and would call me on Monday. I waited all day yesterday for the call and when I got home I left a message on her cell phone to call me. She called back and told me she sold the car to a gentleman about 3:00 P.M. She said she thought I was going to call her but she was suppose to call me. I was ready and excited but sometimes things don't work out the way you want them to. I'm not losing any sleep over this because I will find another one. Have a good Chevy day...Oscar  :cry: 
OSCAR ALBRETSEN
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Oscar,
You should definitely get some nice weather up there. Usually lots of sunshine in Chico.
Weird how the 53 deal went. Good to hear you're not all wacked out about not getting it. Even just re-chromed bumpers cost big bucks. Who knows what other 'needs' it might have had. Altho the purchase price was fairly low. As you say, another one will come along.
Have fun in Durham / Chico.....
Bill.
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Thanks Bill and if I win a trophy for 1st in stock I will be a happy camper...Oscar  :cool2:  
OSCAR ALBRETSEN
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Oscar,
I'll bet you would be. And if you don't it'll still be a great outing. 300 miles in the pick 'em truck!! Change of scenery and so on. You might even spot another '53 Bel Air along the way!!!
Have fun!!!
Bill.
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Oil Can Mechanic
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Installed New Fuel pump from chevs of the 40s. Hesitation is even WORSE now. Cannot even get above 40 MPH without violent
jerking like the car is running out of gas when I try to accelerate???
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Tech Advisor ChatMaster - 25,000
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Check the dip tube in your gas tank. It might be slightly blocked which could also cause your hesitation problem. :) :grin:
The Mangy Old Mutt
"If It's Not Junk.....It's Not Treasure!"
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