By try it do you mean try replacing it same as replacing the ECU box?
Any thoughts on this engine issue
- Thread starter demon34071
- Start date
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By try it do you mean try replacing it same as replacing the ECU box?
Didn't read the whole thread but here ya go.
timing is moving around so its one of three things
1. Light Dist. springs not holding the weights at idle
2. Timing chain bad
3. short in ignition somewhere
timing is moving around so its one of three things
1. Light Dist. springs not holding the weights at idle
2. Timing chain bad
3. short in ignition somewhere
Which would you address first??? The timing chain has zero miles and only break in time and idling time... was new when I had the engine built.
I can add these to the list of items to check...
Leadfoot
Jane Goodall of the N&P Forum
It's the simplest vacuum check there is. Just try to draw air through the tube. You either can or can't.
seabee
Well-Known Member
Those who have already replied have vast amounts of more knowledge than I but I recently had something similar happening to mine so I'll share it in chance that it helps. I could get it to kind of idle out OK but as soon as it got a little bit of throttle it would shake and shudder like one or more cylinders were dead. I attached a compression tester hose to my air filler gauge and did sort of a leak-down test- and found air flowing straight through #5's exhaust at TDC. When I let out that rocker adjustment the valved popped out just the slightest little bit and ever since has run like a champ.
Coronet 500
Well-Known Member
What is the voltage going in and out of ballast resistor while idleing? Does it increase when rpm goes up?
Mopar Al
MOPAR AL
okay here is what we tried with no luck
swapped the ecu -- no change
swapped the distributor -- no change
swapped the carb -- no change
put more gas in it... it ran again, but with no change
Vacuum Guage is reading 12-14
Timing - was at 22-20 initial but was jumping -- rolled it back lower -- still no change
Still getting the idle and rocking like in the initial video....
ANY THOUGHTS???
swapped the ecu -- no change
swapped the distributor -- no change
swapped the carb -- no change
put more gas in it... it ran again, but with no change
Vacuum Guage is reading 12-14
Timing - was at 22-20 initial but was jumping -- rolled it back lower -- still no change
Still getting the idle and rocking like in the initial video....
ANY THOUGHTS???
OldmanRick
Well-Known Member
Bulldozer
free ice cream sandwiches
maybe it jumped a tooth. may sound dumb but, have you verified the firing order and is it clockwise rotation on the cap.
Rick,
As I am in the process of learning I was reading throught this thread. Idling is of course an issue I have as well. I do not have the bucking as this member has. But I am interested in why you have concenrn for the position of the filter?
Do you have a theory?
As I am in the process of learning I was reading throught this thread. Idling is of course an issue I have as well. I do not have the bucking as this member has. But I am interested in why you have concenrn for the position of the filter?
Do you have a theory?
Bulldozer
free ice cream sandwiches
i run 3 filters , an electric pump, a regulator , and a factory pump. all feeding a holley 600. overkill, maybe, clean gas and a solid 5.5 pound of fuel pressure gauranteed lol
OldmanRick
Well-Known Member
I've never run a filter behind a mechanical pump without a electric behind it. I've read where some filters don't like to be pulled but rather pushed. I thought when i saw that, that maybe some filters may contract inside if being sucked (lol) and cause pulsations in the fuel flow. I'm really not positive, but i thought i would throw it out there for them to try.
Bulldozer
free ice cream sandwiches
its not a fuel filter issue. Reason this is ruled out is that we have a fuel gauge right on the fuel rail to the carb and it is hold at 5.5-6.5 psi at all times which is what the pump should be. So there is no spike or dip in the fuel pressure corresponding with the bucking of the motor...
Okay so here is what we did tonight and nothing solved the bucking issue:
swapped out all of the following and individually tested (ecu box, distributor, coil, carb) All swapped items were good and working prior to swapping. The bucking still persisted.
Couple items to note:
The engine smooths out above 1400-1500 rpm or anytime we get on the throttle. Bucking only shows up at idle.
Vacuum gauge with carb on the motor bounces a lot between 12-14. Did a carb swap and it held vacuum more stable but not nearly as high. With either carb when we deliberately uncapped the vacuum creating a leak it runs better with a little less bucking but does still bucks some.
Timing we have tried everything all over the from 14-17 initial to higher around 20-24 and both are about the same nor do they eliminate the bucking.
So out of ideas we did a compression leak test on all of the cylinders and they are all within 150 - 155 - 160 range and hold. While doing this read read the plugs and they are definitely reading rich
Then we pulled the valve covers and cycled the engine a few time to visually verify that the valve tran was all moving - Yes it is......
At this point both point both Mopar Al and myself are out of ideas..... We are open to any thoughts that we have not already tried....
trust me have tried a lot... 4 carbs, 2 dist, 2 coil, 2 ecu's, 3 fuel pumps... compression test, timing, vacuum gauge....
Okay so here is what we did tonight and nothing solved the bucking issue:
swapped out all of the following and individually tested (ecu box, distributor, coil, carb) All swapped items were good and working prior to swapping. The bucking still persisted.
Couple items to note:
The engine smooths out above 1400-1500 rpm or anytime we get on the throttle. Bucking only shows up at idle.
Vacuum gauge with carb on the motor bounces a lot between 12-14. Did a carb swap and it held vacuum more stable but not nearly as high. With either carb when we deliberately uncapped the vacuum creating a leak it runs better with a little less bucking but does still bucks some.
Timing we have tried everything all over the from 14-17 initial to higher around 20-24 and both are about the same nor do they eliminate the bucking.
So out of ideas we did a compression leak test on all of the cylinders and they are all within 150 - 155 - 160 range and hold. While doing this read read the plugs and they are definitely reading rich
Then we pulled the valve covers and cycled the engine a few time to visually verify that the valve tran was all moving - Yes it is......
At this point both point both Mopar Al and myself are out of ideas..... We are open to any thoughts that we have not already tried....
trust me have tried a lot... 4 carbs, 2 dist, 2 coil, 2 ecu's, 3 fuel pumps... compression test, timing, vacuum gauge....
Bulldozer
free ice cream sandwiches
i would pull the timing cover. this is sounding more and more like it jumped a tooth. is the firing clockwise rotation on the cap? may sound like a dumb question, but it has been known to happen lol
Demon,
Maybe it would not be a bad idea to just bypass the filter? Even in new cars with fuel pumps in the tank, the filter is after the pump. I think fluid dynamics rules indicate that it is never wise to put flow restriction on the inlet side of any pump. Could not hurt to rule it out.
Maybe it would not be a bad idea to just bypass the filter? Even in new cars with fuel pumps in the tank, the filter is after the pump. I think fluid dynamics rules indicate that it is never wise to put flow restriction on the inlet side of any pump. Could not hurt to rule it out.
I know a lot of you keep mentioning the fuel filter, fuel pressure, etc.... we have addressed this possibility already and....
Its not the fuel filter or the pump since we get the exact same results when running from a gas can bypassing the filter. Its not the fuel pressure as we have a gauge that is built into the fuel rail and it reads and holds at 5.5-6.5 psi which is exactly what the fuel pump is rated for so it is pumping just fine.
As for the plug wires -- yes we did double, triple, and quadruple checked that the both the firing order was correct and that all of the plug wires were actually pushed on tight. We did a distributor swap and still no change.
Neither of these would explain why the engine smooths out when your on the gas?? Nor would they explain why when we have a deliberate vacuum leak it smooths out some but still bucks....
We are definitely stumped......
Its not the fuel filter or the pump since we get the exact same results when running from a gas can bypassing the filter. Its not the fuel pressure as we have a gauge that is built into the fuel rail and it reads and holds at 5.5-6.5 psi which is exactly what the fuel pump is rated for so it is pumping just fine.
As for the plug wires -- yes we did double, triple, and quadruple checked that the both the firing order was correct and that all of the plug wires were actually pushed on tight. We did a distributor swap and still no change.
Neither of these would explain why the engine smooths out when your on the gas?? Nor would they explain why when we have a deliberate vacuum leak it smooths out some but still bucks....
We are definitely stumped......
OldmanRick
Well-Known Member
Not sure if your running a PCV valve? couldn't see one in the video. The reason i bring this up is a cheap or mismatched valve can flutter at idle with the low vacuum of a choppy cam.
Just tryin to help
.
Just tryin to help
.Bulldozer
free ice cream sandwiches
this is a mystery and i will not rest until this is solved. if you have exhausted and replaced everything outside the engine, its time to dig in. i would start right at the timing cover.
what causes a surge/"bucking" ?
vacuum leak (s)
a stretched chain or timing has jumped
any kind of fluctuating fuel pressure
because you have eliminated the fuel pressure and any vacuum leaks , that really leaves only the timing. everything is coming back to the timing. you say it is jumping around?
are you sure the mufflers are full of mud? lol
what causes a surge/"bucking" ?
vacuum leak (s)
a stretched chain or timing has jumped
any kind of fluctuating fuel pressure
because you have eliminated the fuel pressure and any vacuum leaks , that really leaves only the timing. everything is coming back to the timing. you say it is jumping around?
are you sure the mufflers are full of mud? lol
412 Stroker
Well-Known Member
What about the bushing in the block that the distributer drive gear goes through if there is slop in there wouldn't that possibly affect timming?? or maybe the drive gear/shaft is worn?? you seem to have checked all the basics, and if the timming chain is new I doubt that it jumped, you have all steel gears, no nylon right??
I agree that you seemed to have done all of the basic and easy stuff. Last easy thing would be to check the vacuum hose connection to the correct port (I am sure that you did this on the carb swap) and inspect the valve springs for integrity.
Then it is pulling the intake and check the condition of the cam and lifters. Check the distributor bushing/gear as suggested above.
Next, pull the timing chain cover and remove the cam and inspect for corrosion of the bearings.
Then, pull the heads and inspect the cylinder walls for pitting.
Finally, pull the crank and pistons. Hot tank the block, and reassemble with new rings and bearings.
Then it is pulling the intake and check the condition of the cam and lifters. Check the distributor bushing/gear as suggested above.
Next, pull the timing chain cover and remove the cam and inspect for corrosion of the bearings.
Then, pull the heads and inspect the cylinder walls for pitting.
Finally, pull the crank and pistons. Hot tank the block, and reassemble with new rings and bearings.
Demon,
As I read throught the thread I did not see where you had bypassed the filter using the gravity feed option. So that certainly rules out the filter.
Way past my paygrade, but it sure seems like something is causing the idle circuit to go nuts. But what? That is the big question.
You did say plugs indicate rich. So what can you do to lean it out? Rich charge burns faster, so at idle that can not be good. Once off idle all is OK. So idle circuit is the focus. I am no carb expert, but what does one do to lean out an idle circuit? When I watched the video it does not appear that changing the idle screws had much impact. Just like many throwing stuff out there.
As I read throught the thread I did not see where you had bypassed the filter using the gravity feed option. So that certainly rules out the filter.
Way past my paygrade, but it sure seems like something is causing the idle circuit to go nuts. But what? That is the big question.
You did say plugs indicate rich. So what can you do to lean it out? Rich charge burns faster, so at idle that can not be good. Once off idle all is OK. So idle circuit is the focus. I am no carb expert, but what does one do to lean out an idle circuit? When I watched the video it does not appear that changing the idle screws had much impact. Just like many throwing stuff out there.
Abodee,
Can you really refer to this as a surge? A surge to me is an engine that is searching. Like a gradual increase and decrease in RPM. But this engine is bucking and unless I am mistaken I think I saw where they have observed the timing and it shows no fluctuation. Now perhaps if the damper does have full degree markings they should hook the light to each cylinder and observe the timing. If they have marks at 90 180 and 270 they can at least see if any funky stuff is going on other than #1. What do you think?
Can you really refer to this as a surge? A surge to me is an engine that is searching. Like a gradual increase and decrease in RPM. But this engine is bucking and unless I am mistaken I think I saw where they have observed the timing and it shows no fluctuation. Now perhaps if the damper does have full degree markings they should hook the light to each cylinder and observe the timing. If they have marks at 90 180 and 270 they can at least see if any funky stuff is going on other than #1. What do you think?
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