Hesitation after burnout.

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Hansen

Hansen

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Hi, LA 360 here with a A727 3:23 gears 8.75 rear. street/strip cam and holley 670 4150 vaccum seconds. So i was out testing the car for vibrations after checking out pinion angle. So i lifted the trans about a half inch to get somewhat correct pinion angle only thing i did before test driving. Anyways; did a few pulls worked like a charm like it always have. Started doing donuts but then, right after i was done it started hesitating and started makikg a ticking sound when accelerating too fast. Revs perfect in natural but hesitates when going to fast on the throttle and this small repeated ticking sound comes. When ticking sound goes away it starts accelerating. Changed the coil and checked the distributor for any failures. everything looks good.

update: swaped the carb for a double pumper and fixed the timing from 60 to 34. Works fine again. Thanks for any input.

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Hansen said:
Hi, LA 360 here with a A727 3:23 gears 8.75 rear. street/strip cam and holley 670 4150 vaccum seconds. So i was out testing the car for vibrations after checking out pinion angle. So i lifted the trans about a half inch to get somewhat correct pinion angle only thing i did before test driving. Anyways; did a few pulls worked like a charm like it always have. Started doing donuts but then, right after i was done it started hesitating and started makikg a ticking sound when accelerating too fast. Revs perfect in natural but hesitates when going to fast on the throttle and this small repeated ticking sound comes. When ticking sound goes away it starts accelerating. Changed the coil and checked the distributor for any failures. everything looks good.

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Hyd. lifter collapse ??
 
a leaking plug wire, the ticking could be arcing...
 
I would ohm out the plug wires & the coil wire to see if they might be breaking down internally, or check the power valve to see if it's popped.
 
Demonracer said:
I would ohm out the plug wires & the coil wire to see if they might be breaking down internally, or check the power valve to see if it's popped.
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would you hear it if there was a popped power valve? Can vaccum secondaries have anything to say?
 
Hansen said:
To check this i assume i need to pull the valve covers and check the lifters from there?
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Ever see the episode of Road Kill where they destroyed the motor in the "Disgustang"?
They were doing donuts and lost oil pressure because of oil slosh in the pan.
 
Hansen said:
would you hear it if there was a popped power valve? Can vaccum secondaries have anything to say?
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You probably won't be able to hear it, but it will run rich & have a stumble. You can change the spring in the vacuum secondary pod to a lighter spring to see if that any affect. Just make one change at a time until you resolve the problem. Multiple changes will have you scratching your head, wondering which one fixed the problem, or made it worse.
 
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Update: the distributor had rotaded and had 60 degrees at 3000 rpm, gonna test drive now
 
Hansen said:
Wouldn’t this be seen in neutral? Reving in park has no ticking and accelerates good
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not necessarily
in neutral there is no load on the engine, and it would take less for the plug to fire
under load, this changes and the path of least resistance for the spark may not be through the plug, but arching through the wire


as for the collapsed lifter, that is easy to spot
you simply pop the valve cover off and look for a rocker not moving
 
What kind of motor mounts do you have? Did you break one causing the motor to lay over at high punch it times? Seen it cause all kinds of problems. I think video would be extremely helpful to the diagnosis.
 
If it sounds like a munch of marbles in a tin can then its detonation. If it is then stop and find out what is going on, continued detonation will hard the engine. Do the secondarys move freely? What is you static timing and total? Are you running vacuum advance?
 
Since loose distributors will move in the direction of retarding timing, something else probably moved the distributor in the advance direction.

Hansen ought to look at where the vacuum advance pod is pointing and see if it possibly hit something like the firewall as the engine moved while doing those donuts and burnouts. I've had this happen in a rally car slamming over a huge rock... knocked the distributor vacuum pod into the frame rail and advanced timing about 40*!
 
Update: fixed the distributor to 34 degrees but still had hesitation. pulled the 670 vaccum secondaries holley, and put a 600 double pumper. works very good again.

But now; what is wrong with the 670? any way to test these?
 
Update:

Still have hesitation after changing carb.
Test drived it today, and it if i give more then half throttle it hesitates.. it gets better after a after driving a few minutes.
 
At it's very basics. A hesitation is equal to hunting for more fuel. The motor is waiting for something to ignite. When it finally collects enough and catches up, "Bam", off she goes again.

A sputter is the opposite. The ***** is drowning and has to spit some out before she catches up again.

And when you say you give it. Is this a slow or a fast given. Are we mashing or getting on an on ramp at the freeway? or is it autobahn
 
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Hansen said:
Update:

Still have hesitation after changing carb.
Test drived it today, and it if i give more then half throttle it hesitates.. it gets better after a after driving a few minutes.
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What is meant by saying " it gets better after a few minutes'? Does this mean that the engine is only partially warmed up when it hesitates?
 
nm9stheham said:
What is meant by saying " it gets better after a few minutes'? Does this mean that the engine is only partially warmed up when it hesitates?
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The hesitation goes away slightly when the engine gets warmer, but it's very unlikely that the carb is acting up as i swapped it and gave it much fuel to work with without it being too much. I am suspecting a ignition fault..
 
Well, if we are going to keep spit balling. Then my brain computes with the minimal information and taking your description at your word (and assuming we are using a similar motorhead vocabulary) . Plugs are at least one or two ranges to cold. What are you running?

But.... I went back and re-read your initial post. You have to locate what happened during the incident to cause this. Do you have good ground straps from the motor to the body. Recheck them. Recheck all your grounds. Did you crack your cap? It is showing any arcing? Try a different one.

Is the ticking noise still there?
 
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Hansen said:
Update: fixed the distributor to 34 degrees but still had hesitation. pulled the 670 vaccum secondaries holley, and put a 600 double pumper. works very good again.

But now; what is wrong with the 670? any way to test these?
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The bleeds/restrictors. That's a economical fuel saver carb for rv cam truck motors.
Sell it. Plain 600 is a better carb.
It's always been the case any other car works better then the Avenger once it's out of it's stockish element
 
Blind Squirrel said:
Well, if we are going to keep spit balling. Then my brain computes with the minimal information and taking your description at your word (and assuming we are using a similar motorhead vocabulary) . Plugs are at least one or two ranges to cold. What are you running?

But.... I went back and re-read your initial post. You have to locate what happened during the incident to cause this. Do you have good ground straps from the motor to the body. Recheck them. Recheck all your grounds. Did you crack your cap? It is showing any arcing? Try a different one.

Is the ticking noise still there?
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Ticking is not there any more, it was detonation from the distributor being set waay to advanced.. will check wiring, may have happend something when doing the donuts. WDYM when you say two ranges of cold in plugs?
 
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