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Discussion Starter · #1 ·
A while back I made a post about my car missing and sputtering under full throttle. I have never been able to get it to stop.
Last night it got a lot worse. I was driving down the freeway at about 75mph. All of a sudden the motor started missing and making a pinging noise, sounds like a car hitting the rev limiter. (It's a stock 305, with 8.0:1 comp. so I don't think it's being caused by detonation) I had to slow down to 20. If I thouched the gas more than a fraction it would start missing again. I went about a mile and pulled over. It idle fine and was not overly hot. I got back in, same thing, could only go 20. After about 1/2 a mile it went away. Now it only does it when the motor is really cold or under full throtttle.
I thought it might be caused by the coil, but I changed it last week trying to cure the full load ping. It had no effect. Last night was the first time it ever happened when the motor was not under full load.
The motor is coming out next week anyways, but I still want to try and fix it.

Thanks for any help
Steve
 

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Have you checked your choke? Is it electric or manual? Same thing happened when my choke stuck in a partially closed position. Also when's the last time you checked your timing?
 

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Discussion Starter · #3 ·
Choke was all the way open and timming was around 36 and I pulled it back to 30 with out effect.

Steve
 

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wanarace,

My '69 did exactly the same thing last year until it finally stalled and left me stranded at the local Tim Horton's. I'm convinced your vehicle's symptoms are identical to what mine were. I knew it was something electrical but I didn't know what.

After changing the spark plugs, distributor cap, and rotor, I finally got to the bottom of it. The points.

They were completely shot. This explains why sometimes the car would run fine and other times it would darn near quit in the middle of the highway.

Change your points.
 

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Discussion Starter · #5 ·
I would love to change the points, the only problem is I am running an HEI.
This is the second distributor, the change had no effect.

Thanks for the suggesstion.

Steve
 

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just a possibility, if you are runnung an external voltage regulator, and it is bad, it wont charge your electrical system properly. I had a similar problem where this happened and I replaced the entire alternator with a single wire alternator. problem solved, couldnt hurt to check...
 

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Sounds like carburation problems to me. Try swaping yours out to see if that makes an impact. If you don't have access to another carb, look into your while giving it gas. Does it spray or dribble?


rlk

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70SS LS6 coupe
71SS LS5 elk
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Check two things:

1.Fuel filter
2.Fuel line

Sounds like you are getting very little fuel!

You've tried more than one ignition system, and it idles fine. Carbs don't just stop working unless they are not getting fuel or you have some $hit in the bowls or jets.

Humor me and change the filter!

[This message has been edited by 505_Malibu (edited 05-31-2001).]
 

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Discussion Starter · #9 ·
My external regulator was toast, so I put in a 10SI alt with internal regulator. Electrical is working fine.

I will have to look into the carb thing. I rebuilt the carb last summer and changed the filter about 4 weeks ago. I had a post about this a while ago but can't remeber the outcome. When I took the filter out the closed end was all mangled and bent up. I have no idea why. It is the long style Q-jet filter, and it did not bottom out when I tightened the retaining nut. I will pull out the filter in there and see if the same thing happened.

Fuel problem would make sense. If mixture leans out it would cause these problems. Carb has other problems, car stumbles when coming to a stop. Which means the float is probably to low, or else the bowl is just not filling up.
I am not too worried, the motor is coming out by the end of the month, and I will run a new larger fuel line and add a sump to the tank. The 327 will get a 650 Vac Secondary or 650 Dbl Pumper. So my fuel problem will be solved.

Thanks
Steve



[This message has been edited by wanarace (edited 05-31-2001).]
 

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My 69 did a very similar thing - idle just beautiful, under any load though, it would miss, crap out, and was generally sputtery. I rebuilt the carb under suggestion of the local pro shop (holley 750) but made no effect.

It turned out to be the mechanical fuel pump. I think it was a partially worn diaphragm, not certain. Anyway, it was working well enough to keep the fuel bowl full at idle, but would quickly run out of gas under accel, as there was no pressure on demand. I suggest putting a fuel pressure guage at the carb and see what pressure you have at load. Good luck...
R

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1969 300 Deluxe HTSS396/ 1971 Malibu 2DR HT
"Never let fear and good judgement hold you back."
TC Member#1276 [email protected]

[This message has been edited by Bow_Tied (edited 05-31-2001).]
 

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I've had what sounds like the same thing on two different cars- I'm with 505_Malibu and Bow_Tied - Fuel filter or fuel pump.

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Make it the way you like it, forget what the other guys say!
 

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I had the same problem a few years ago with a Chevelle that had a Fram HPG-1 fuel filter. The filter became plugged to the point that it would flow just enough fuel for the car to run on a level road about 60 mph. Any faster or under load up a hill, the engine would start to cut off just as if the ignition had an intermittant failure. A pressure gauge showed that I had adequate pressure at idle, but the engine just wasn't getting an adequate volume of fuel.

[This message has been edited by Hotrod65SS (edited 06-01-2001).]
 

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Discussion Starter · #13 ·
I have an extra pump so I will try it.

Thanks
Steve
 
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