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Old 04-26-2014, 01:44 PM   #1
66_grn_fstbk
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Default stumble on acceleration

Hi all-

So my 66 fastback, which has not been driven a while, has developed a pretty good stumble when I hit the gas hard. In fact, it almost stalls when I hit it hard. Likewise it seems to be close to stalling once warm and sitting at a light.

It has a mildly warmed over 289, with a holley 600 vaccuum secondary and a pertronix distributor. At one point in the past a mechanic told me that the mechanical advance on the distributor was sticking, he said he fixed it, but did not tell me how to know if the issue was casuing the problem I had brought the car in to before. How might I check to see if indeed that is the issue now.

I have checked for vaccuum leaks and have not found any, even using a little liquid around the base around the carb. I have used a huge amount of carb cleaner to get rid of any shellac buildup, but that hasnt really helped.

Any help would be appreciated

cheers
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Old 04-26-2014, 07:34 PM   #2
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sounds like a bad accelerator pump in the carb.

Take the air cleaner off and with the engine off apply full throttle by moving the accel linkage. At the same time look down the carb you should see two solid streams of fuel **** into the front barrels of the carb.

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Old 04-27-2014, 07:25 AM   #3
barnett468
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Quote:
Originally Posted by 66_grn_fstbk View Post
Hi all- So my 66 fastback, which has not been driven a while, has developed a pretty good stumble when I hit the gas hard. In fact, it almost stalls when I hit it hard. Likewise it seems to be close to stalling once warm and sitting at a light.

It has a mildly warmed over 289, with a holley 600 vaccuum secondary and a pertronix distributor. At one point in the past a mechanic told me that the mechanical advance on the distributor was sticking, he said he fixed it, but did not tell me how to know if the issue was casuing the problem I had brought the car in to before. How might I check to see if indeed that is the issue now.
Hello;

you might have a few problems. i would do the following after the inspection mentioned above.

remove all vacuum lines including the pcv and plug the fittings for them on the carb, not the hoses.

spray flammable brake cleaner, not carb cleaner, using the long nozzle genty at the carb base and intake at the heads. if the rpm goes up you have an air leak. if the prob still exists, i would do the following.

1. remove the dist cap and turn rotate the rotor a hair then let it go. it should return. if it does not it either needs the spring tension adjusted or it has a bad spring or it is sticking.

2. remove dist vac hose and check timing at idle. it should be around 6 degrees btdc. set it if it is not.

3. check for vacuum on dist hose at idle, there should be none. if there is then do not connect the **** yet.

4. remove screws in psassenger sideb of carb float bowls. if more than 1 drop of gas comes out, your gas level is too high. it should be a little below the bottom of the inspection hole. if it is not then adjust it.

5. turn one idle mix sctrew out one turn for 5 seconds then in all the way for 5 seconds then back out to the previous setting then do the same with the other ine. if one has no effect your idle c circuit is plugged up on that side. if both have some effect but don't fix the problem, your power valve might be leaking.
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Old 04-29-2014, 02:16 PM   #4
66_grn_fstbk
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thanks guys.. checked the accelerator pump, two nice sprays. Will check the remainder of the suggestions this weekend!

thanks
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Old 04-29-2014, 02:16 PM
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