750 aed stumble off idle/start

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1 Bad Duster

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I have a 750 aed carb I messed with the acclerator pump cam and the stumble went away a little. Then I messed with the squirters and it went away alittle more but its still there..I went from 31 front an 35 rear to a 40 front an 42 rear squirters, Thanks Jimmy
 
accelerator pump linkage........primary and secondary

[ame="https://www.youtube.com/watch?v=k-Nx5HEzvlY"]How To Adjust The Accelerator Pump On Holley Carburetors - YouTube[/ame]
 
thanks so I gotta mess with the accelerator pump cam more I messed with the front one and I noticed there is a back one should I adjust that one also. an if so should it be like the front use a .15 feeler gauge
 
Where's the initial timing set?
 
Where's the initial timing set?


I haven't had a timing light on the car yet. I know at the track I advanced it a little it picked up 2 tenths an 2mph in the 1/8. Then I came back an advanced it a little more and it was hard to start. so I turned it back down a little and it fired right up. But it ran the same. I was shifting at 6500 rpm then I came back after a cool down an turn up the shift light to 7K It ran the same time but it picked up 2mph.
 
set the timing with a timing light......LOL...
 
I'am not familar with that carb but it sounds like a holley. A classic mistake when setting the accelerator linkage is to have play in it when its at an idle. The .015 you mentioned. There should be no play. The shooter should squirt fuel instantly when the throttle is touched. Same for the secondaries. That .015 is for wide open throttle to make sure the linkage doesnt bottom out.
 
As for timing the first thing to do is find top dead center and see if your marks on the dampner are correct. The marks can be off for a variety of reasons so find TDC first!
 
Timing first. Timing, Timing Timing, first..................................Timing first.

Idle timing. Power timing including the rpm at which it is all in by;not some arbitrary number. Cruise timing
Example;
Power timing 38* all in by 3600rpm. Still 38* at 4000
Idle timing with above power timing is 12*@ 700rpm. Begins advancing at 1000
Cruise timing;Dont know/dont care, Im just interested in getting rid of the tip-in hesitation.
See how that works? Now heres the deal why; If you change the idle timing, it changes the idle speed. So you change the speed back. But then you have to readjust the A-pump. Plus you have to limit the power timing so the engine doesn't self destruct.More is not necessarily better.If you change the power timing, well that changes the idle timing, and you are back to that whole thing again.
Then if you change the cam, you get to start all over again. And sometimes going from one exhaust system to another, you also get to start over. Or if you move to a different location at a different altitude, yup, back to square one.
So, if you value your engine,Prove the balancer TDC, and buy a good light,cuz you're gonna need it.
Theres a real good chance that you'll get to put the original parts back on the carb, once the timing thing is worked out.
 
As for timing the first thing to do is find top dead center and see if your marks on the dampner are correct. The marks can be off for a variety of reasons so find TDC first!

When I find top dead center the piston all way up the lines doesn't match. But with the lines matched up the piston has started to move down just a tad. I know i added 80 fronts an 88 rear jets an tge stumble/hesitating is gone off start.
 
On most carbs, the jet size has almost nothing to do with a tip-in hesitation or even a part-throttle bog.
And if your jet sizes get to be bigger than they need to be, you will wash the oil off the cylinder walls(in addition to losing power). This will lead to accelerated ring and bore wear, and the gas in the oil won't help the cam and bearings one bit.
So yeah, get the timing worked out first. Then the jet sizes.Then the PV timing. Then dial in the pump system.And lastly the Vcan.
To make things easy for myself, I often defeat the secondaries, and dial in the primary jets all by their lonesome.
 
So the timing marks have slipped back on the hub. Thats what they do. I your going to keep that balancer put a paint line across the front so you can keep track of how much it slips. Then find tdc and correct the marks. Even if you get a new dampner you still gotta check tdc. Did you take the play out of the accellerater pump linkage?
 
What size engine..??
What intake manifold..??
Is it an automatic..??
What is the rear gear ratio..???
It's a 340 30 over its a Victor 340, yes it's an automatic, 456 gear

So the timing marks have slipped back on the hub. Thats what they do. I your going to keep that balancer put a paint line across the front so you can keep track of how much it slips. Then find tdc and correct the marks. Even if you get a new dampner you still gotta check tdc. Did you take the play out of the accellerater pump linkage?

The line on the balancer for top dead center when it's at the mark the piston has started to move down just a tad. So your saying the balancer isn't good. Yes I messed with the accelerator pump linkage an after I changed the jets the car seems to idle an run an pull better threw the gears.
 
Your dampner/balancer is still functional. But not in top notch shape. So its best to keep an eye on it. Thats what the paint is for. You need to know if the slipping has happened recently or if its been just a tiny bit for quite a while now. If its slipping fast you need to change it. If you can see that it has moved at all say in 2 weeks time,change it. Thats an everyday driver,right?
As for the carb. Adjusting the accellerator linkage wrong is a common mistake. Holley instructions were not written clearly at all. I know its an AEM? carb but when you mentioned 0.015 feeler gauge clearance well that made me think 'classic mistake'. Remove that clearance, make sure its squirting fuel with the slightest touch of the throttle and you should have no doubt that the bog is gone. Then go back to your original jetting. You will be much happier.
 
Your dampner/balancer is still functional. But not in top notch shape. So its best to keep an eye on it. Thats what the paint is for. You need to know if the slipping has happened recently or if its been just a tiny bit for quite a while now. If its slipping fast you need to change it. If you can see that it has moved at all say in 2 weeks time,change it. Thats an everyday driver,right?
As for the carb. Adjusting the accellerator linkage wrong is a common mistake. Holley instructions were not written clearly at all. I know its an AEM? carb but when you mentioned 0.015 feeler gauge clearance well that made me think 'classic mistake'. Remove that clearance, make sure its squirting fuel with the slightest touch of the throttle and you should have no doubt that the bog is gone. Then go back to your original jetting. You will be much happier.


NO its not a daily driver Its just a weekend warrior. I adjust the accellerator pump with it like you mention. an I took the 40 an 42 squirters out an put in 37 front an 37 back. an I added a 2 inch spacer. an I believe it idles and revs up alot quicker an no bog from 0 to wot nomore in park.
 
Simple test.

Get car warmed up, twist distributor a bit CCW, if the engine picked up RPM it wants the timing at idle. Reset idle speed and do it again. Find the max point that the car still starts when hot without dragging badly or kicking back.

As someone else said... TIMING FIRST!!!!

Once you get that sorted out, your entire carb tuning set up will change.
 
Simple test.

Get car warmed up, twist distributor a bit CCW, if the engine picked up RPM it wants the timing at idle. Reset idle speed and do it again. Find the max point that the car still starts when hot without dragging badly or kicking back.

As someone else said... TIMING FIRST!!!!



Once you get that sorted out, your entire carb tuning set up will change.

I did this this morning an my car picked up rpm. An i set it to where my car would start up one time i did it it seemed like my battery was dead so i turn it back till it turned over an started easier. I lowered my fuel pressure from about 7.5 down to 6 psi.
 
Lowered the pressure down to 6lbs. Your carb will like that. Good move.
 
Ok i hooked a vacuum gague to the car it was around 4-5 an i adjusted the carb an got 8-10 out of it. But i couldnt get anymore. But it doesnt have the stumble or hesitation anymore.
 
I took off the 750 aed an put on a 950 proform n the car sounds,more radical an it pulls harder threw all the gears to 6500-7000k.
 
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